Planning Workshop

Good morning and welcome everybody,

Three years ago I had the very pleasurable experience of re-discovering the magnificent ruins of Teotihuacan -north of Mexico City- through the eyes of Linda Manzanilla, a respected archeologist from the National University who recently made the cover of the National Geographic magazine. She had been working not on the great ceremonial pyramids and avenues of the old empire but on the dwellings of common citizens in Teotihuacan. I then also discovered that archeological activities were no longer reduced to digging, cleaning ancestral clay objects and, if one made a truly important discovery, having the BBC produce a documentary on your unveiling of new facts about ancient civilizations. In fact, archeology was making a tremendously good use of scientific tools not only in dating objects, but in describing what kind of food was ingested and what were the everyday habits of those citizens. This, I soon found out, was determined by doing chemical analyses of garbage, the remains of the kitchen and among other things, fossil feces.

Teotihuacan was a large metropolitan area during its classical period (around 700 a.c.) with an estimated population of 150,000 and an economy based not so much in warfare but in commerce. The Teotihuacanos managed to dominate the commercial routes of several civilizations to the extent that one can find their architectonic influence as far south as in Tikal, the largest Mayan ceremonial center in the heart of Guatemala, as well as on the northern states of Mexico.

Now, you will think I missed the point of this workshop but bear with me for a few minutes. Manzanilla explained to us that each wall, step and ceiling in the large, ceremonial center was covered with stucco, a material that required large amounts of fuel for its cooking. Fuel in the 8th-century meant wood. In addition, there was a rapid increase in population due to an intense migration from neighboring communities. As in ancient Rome, Teotihuacan was the Mesoamerican empire and therefore many individuals migrated to the city to pursue a better life. Current theories on the demise of the Teotihuacan civilization point towards an overexploitation of natural resources that soon made social life in the region unsustainable. Local climate change due to the destruction of forests and soil erosion dramatically changed agricultural cycles to the extent that the city was no longer self sufficient in its most basic needs. Several anthropologists and historians suggest that a similar process occurred during the decline and eventual disappearance of Mayan civilizations.

This story shows us two lessons. The first one is the tremendous power of scientific mind tools to understand a puzzle that involves one of the most complex problems for human comprehension: the behavior of human society itself and how it determines its own future. And let me be precise. By scientific mind tools I do not mean the use of analytical physical or chemical theories and measurements but a state of mind that prepares us to use certain skills to understand a phenomenon and how to put everything together in a coherent manner. The recognition of certain patterns, the identification of cause and effect, to test and accept objective evidence and the rejection of unsupported dogmatic beliefs are all part of the scientific toolbox we, the members of this collaborative group, carry within our minds.

The second lesson is related to the limits of growth. Unfortunately, past social and economic models have not placed an adequate economic value to certain natural resources that were thought to be inexhaustible. Our archeologist friend once said: "There is enough evidence in Teotihuacan to suggest that the collapse of a large metropolitan civilization is completely feasible." Mexico City is only 50 kilometers away from Teotihuacan and its northern, industrial suburbs are rapidly expanding towards this mute witness of uncontrollable growth and collapse. Fortunately, we are now beginning to understand the dynamics of human consumption and its toll on the environment. Human communitiesrural, urban or mega-urbanare part of an ecosystem regardless of their dimensions and we must learn how to maintain a sustainable equilibrium within their ecological boundaries.

I understand that our task during this workshop is to design some of the tools that will help us in this learning expedition. Or, as Luisa and Mario Molina state: "The Case Study of Mexico City is designed to advance the basic understanding of the relationship between urban, regional and global air pollution, to improve decision and analysis tools available to decision makers and their ability to implement them, and to develop general guidelines for integrated assessments."

We are indeed very fortunate, at least in the sense that we are able to bring together the perspectives of expert minds in different fields of knowledge. And since we want to advance our understanding of urban, regional and global air pollution it could not be otherwise. Such a task necessarily requires the input of interdisciplinary research. I like to think of this workshop as an exercise in Collective Intelligence to borrow and adapt a concept from the French sociologist Pierre Lévy. The idea is to build aknowledge space by sharing the skills and understanding on air quality issues from each member of the group. The contrasting perspectives from social, health and natural scientists can only promote the multidimensional character of this knowledge space. Therefore, this is an academic meeting in the sense that our work will be devoted to bring knowledge to life.

In the name of the US/Mexico Foundation for Science and the organizing committee, let me welcome you again. I also want to express our acknowledgement to Mario and Luisa Molina for their initiative in suggesting this bi-national research collaboration, and to Francisco Guzmán and Marisa Ruiz for their enthusiastic "catching the ball" on this side of the border. Thank you all for your participation in this workshop.

Workshop Overview

Air pollution in Mexico City is widely recognized by the government and by citizens as a serious problem, although its impact on human health remains difficult to determine. The severity of Mexico City's problem arises both from demographics and geography: a very large population engages in polluting activities in a valley enclosed by mountains. Local and federal governments have already implemented a number of pollution control policies, from closing refineries in the basin to prohibiting people from driving on certain days, but the pollution remains among the worst in the world.

This collaborative project aims to perform an integrated assessment in which scientific and policy research will be coordinated to provide input to decision making. A central goal is to assess control measuresusing existing data and common and accepted modelsagainst criteria of technical feasibility, cost-effectiveness, and social/political acceptability. The project also aims to identify critical areas of uncertainty, to provide a case study for use in disciplinary research, to train professionals in Mexico and the US, and to develop integrated assessment methodologies and tools for handling uncertainty in policy decisions.

Several participants at the meeting voiced the need for better scientific information, where understanding is lacking. The areas of concern included: the lack of high quality measurements of air pollution, a serious lack of knowledge of emissions sources, and a poor characterization of meteorology and air pollutant flows. In addition, a number of questions remain regarding the link between ambient pollutant concentrations, exposure (including indoor exposures), and health impacts. These concerns led several participants to question whether we know enough to provide policy advice.

In contrast, more participants agreed that much is already understood about the problem, and that it is critical to communicate this knowledge to the policy process. For example, measurements show that past pollution controls have significantly decreased concentrations of lead, sulfur dioxide, and carbon monoxide, while there remain considerable challenges to lower levels of ozone, nitrogen oxides, and fine particulates. Evidence also shows clearly that automobile emissions contribute substantially to the observed air pollution problems. Enough is known to adequately define the problem and to propose potential solutions. Research and policy analysis should therefore proceed in parallel, rather than waiting for the science to be "solved."

The importance of vehicular sources suggests that a number of technical remedies may be appropriate in the short term, including improving vehicle emission controls and vehicle maintenance, and changing fuel composition. In the longer term, emissions from transportation will be strongly related to Mexico City's continuing and serious land use and transportation planning problems. Thus there is opportunity to consider air pollution control measures within the context of land use and congestion management. Multi-disciplinary expertise is needed to address such linkages between air pollution and other urban issues, including population growth, poverty, industrial development and regulation, and energy policy, as well as globalization and problems such as climate change.

The political system in Mexico also raises a number of challenges which an integrated assessment must address if it is to effectively inform and influence decision makers. Participants characterized decision-making in Mexico and Mexico City as being very centralized, and not very receptive to outside input. A lack of strategic planning exists in both government and the private sector. Within government, conflicts exist between different agencies with different priorities. There has been a lack of strong leadership to implement initiatives, and there remain serious problems of monitoring and enforcement.

It is important to understand the cultural basis for decision-making and the implementation of policy. Researchers can therefore learn substantially by evaluating past policy actionsan important feedback from government to the assessment process. This project should acknowledge political realities in making recommendations, and should target these recommendations towards specific "clients." Moreover, it should aim to educate both decision makers and the public (by engaging the media) to put environmental issues on their agendas, and to promote the notions that air pollution is a serious problem, but one which can be addressed through appropriate actions.

Brief summaries of each discussion session are presented in the following pages.

Session I: Integrated Assessment

The first discussion addressed aspects of integration, evaluation, community input and public perception, and how to accommodate social criteria, as related to the Mexico City Air Quality Research Initiative (MARI) project, to Mexico, and to integrated assessments in general. The following are some of the key points from the presentations and discussion:

• The MARI project attempted to cover scientific, technical, and social/economic aspects under one umbrella. The project included monitoring, measurement and characterization studies oriented around ozone, and pollution modeling and simulation. Cost and emissions impact of different control options were analyzed using linear optimization, and a decision analysis tree included economic, social, and political factors.
• There is a need to address multiple pollutants and related issues. In both Mexico and the US, enormous public efforts are directed at controlling ozone, although there are many other pollutants with serious health and environmental consequences. A holistic approach would be better. Other issues, such as climate change and land use should be integrated into the analysis of air pollution strategies.
• There are no "right" answers. Analysis should serve to spark discourse and feed the broad debate rather than attempt to provide a final answer. There is a need to identify barriers and produce a set of issues and areas for research and examination, rather than trying to formulate a solution right away.
• Interactions between policy makers and scientists are typically ineffective. Politics can uncouple scientific findings and strategy formulation. There is a need for better models of how science, technology, and policy may interact.
• Social criteria are difficult to quantify but play a significant role in the perception and implementation of policies.Instead of optimizing multiple weighted objectives, integrated assessments can be a mechanism to produce sets of issues that can be evaluated from various perspectives (political, economic, scientific, etc.).
• Community input must be solicited in addition to expert opinion. Community outreach and public education are necessary to improve public understanding of the issues and generate public support for potentially difficult or costly solutions.

Session II: Health Effects

The second session addressed the health effects of air pollution and the role of health authorities in air pollution policy. The following key points were made:

• Ozone exposure significantly reduces breathing capacity, which can cause severe problems for people with asthma or severe or chronic respiratory disease.
• Increases in particulate matter concentrations are associated with increases in mortality. However, a lag of 7-10 days between exposures and health effects makes it difficult to quantify.
• A quick review of major studies and datasets is needed. Mexicans have long-term monitoring data and a sense of the trends and spatial distributions of pollution, but the information is not well organized. Better interpretation of existing data through more rigorous analysis is needed.
• Particulate matter needs to be studied more. Little is known regarding which components of particulate matter are causing health impacts. PM composition varies in different parts of the city and existing standards do not account for this.
• Better exposure data are needed. Even with so much ambient monitoring, information about exposures is important to better understand epidemiological impacts, which might not be directly correlated with average ambient concentrations.
• There is a need to evaluate economic impacts and use this information effectively. It has been estimated that each contingency episode above 240 IMECAS imposes million in health care costs. Health costs associated with lower levels of pollution have not been evaluated.
• Risk perception and communication issues are important. There is a need to educate people that air quality is part of their well-being and that actions can be taken to improve air quality.

Session III: Science Issues

After the presenters provided information about the status of air pollution studies in Mexico City, the discussion began by addressing various fuel-related issues. Mexico's progress with gasoline vapor recovery programs, which are becoming widespread in Mexico City, was discussed, as was the issue of vehicle maintenance. The following points were made:

• The reliability of existing emissions inventory in Mexico is questionable (as is often the case in the US). Ways to generate better data need to be explored.
• Vehicle maintenance has a large impact on emissions.
• Fuel reformation may also lead to significant air quality improvements.
• Diesel vehicles are probably large sources of fine particles; emission controls should be explored.
• LPG is used extensively for indoor cooking and heating. The corresponding emissions should be better characterized (there is information on the contributions to the hydrocarbon budget from LPG leaks from atmospheric measurements).
• The effects of changes in emissions resulting from various control strategies should be explored using appropriate modeling techniques..

Session IV: Public Policy Issues

Influencing public policy is a key aspect of an integrated assessment, with the obstacles being centralized planning, competing environmental, economic and social concerns, and lack of communication between scientists and policy makers. Presenters addressed the relationship between policy and science and engineering, specific transportation and land use policy approaches to reduce mobile-source emissions, the limitations of existing environmental programs in Mexico, and the role of political structure, the media, and society in policy issues. The following key issues were identified in these presentations and the discussion that followed:

• Uncertainty can be managed. Decisions need not be delayed because of uncertainty. There are techniques to accommodate uncertainty in policy analysis.
• Professionals need to be trained across disciplines. A need exists for people who can bridge science/engineering and policy issues in order to address a wide range of multi-dimensional problems.
• Mexico needs to build an adequate institutional framework for policy development and implementation. Environmental policies of different government sectors must be integrated, and environmental criteria are needed to guide the actions of different public agencies.
• Media play a critical role in raising environmental awareness. Public education is important. The roles of NGOs, the church, and the private sector can be more constructive.
• The link between air pollution and global environmental issues presents a strategic opportunity. Transportation policy is crucial for both. Win-win solutions can help decision makers overcome opposition to politically difficulty strategies.
• Regulatory strategies to reduce mobile-source emissions include technology mandates, regulation of land use and transportation infrastructure, and regulation of individual behavior. In the US, technology mandates have been the most effective.

Session V: Bringing it All Together

In the final session of the workshop, participants discussed key elements of the air pollution problem and key issues involved in addressing it. These are summarized here:

• Issues and barriers include large uncertainties/lack of information; bottlenecks on the implementation end; making decisions across sectors of government; lack of enforcement of legislation; market forces; how to include "soft" variables/issues in the analysis; how to convey health impacts/costs; how to communicate risk to the public; how to create governmental credibility
• There is a need to move beyond crisis management. Solutions for the long term should focus on: a multi-disciplinary/multi-issue approach to the problem; cross-sectoral strategies involving institutional interaction/coordination/collaboration; integrated "Plans" developed for different sectors (transportation, economic, environmental); feasible long-term transportation strategies; education that links emissions, pollution, policy actions; connection to climate change issues
• A "serial" approach to integrated assessment should be avoided as there are too many roadblocks.
• Mass media needs to become part of the solution instead of part of the problem. Public knowledge and involvement can be increased via the media.
• Stakeholders need to become involved in decision-making processes in order to devise successful strategies.

Moderator: Mario Molina, MIT
Speakers: Greg McRae, MIT and Francisco Guzmán, Instituto Mexicano del Petróleo

Presentation by Professor Greg McRae

Professor McRae discussed air pollution generally and control strategies in particular, then outlined the principles of an integrated assessment. He reiterated the goal of the workshop: the effort to develop a US-Mexico model to address air pollution problems, a model which then can be applied to other cities around the world.

Air pollution on local, regional and global scales

Prof. McRae described two distinct forms of air pollution: gas phase and aerosol. Only a handful of gas phase pollutants are currently regulatede.g., in the US, ozone, SO₂, NO₂, and CO. Aerosols also have only a few regulations, primarily dealing with visibility. Given that thousands of chemical compounds are involved in air pollution, determining which affect human health and the environment, then devising strategies to control them, is the challenge to meet.

In the US, 70 million people are affected by ozone pollution. Although billion is spent per year on controls, reductions have been minimal. And despite enormous public efforts directed at controlling ozone, there are many other pollutants with serious health and environmental consequences. CO₂ and other greenhouse gases have global environmental impacts; CO, NO_x and organic emissions have urban scale consequences; and particulate pollution and SO_x are largely regional problems (see Figure 2-1). But given that combustion is a common source for all these pollutants, a holistic approach would be more efficient. The question is how to achieve this.

Figure 2-1. Urban, regional and global emissions from fuel combustion.

Public perception and politics are important. He illustrated this with a slide of a power plant in New England with a visible steam plume going in one direction towards Canada while the pollutants emitted from a different stack went another direction. These pollutantsNO_X, SO_X, and CO₂are the products we should be concerned about. The difference in visibility requires that the public aspects of air pollution be carefully managed. He also commented on the international dimensions of pollution politics. One of the methods used to reduce regional and urban concentrations of pollution is to build taller stacks. While this reduces local impacts, it also introduces the possibility of transport across international boundaries. The acid rain problem in the United States is an example of how air pollution becomes an international problem.
Prof. McRae listed several common characteristics of air pollution problems:

• Decisions must be made even in the face of uncertainty.
• Good decisions require the expertise of multiple disciplines, among them engineering, economics, and political science.
• Public education and professional training are needed to increase the number of people who understand the issue at all levels.
• Technology is an important part of the policy solution, especially regarding fuels and combustion.
• Organizational barriers must be overcome.

Under ideal circumstances, interactions between science, technology and policy would flow in all directions. In reality, decisions are often made in isolation. Political pressure to act results in the uncoupling of scientific research and policy formulation. To control acid rain, for example, the US spent a billion dollars on scientific research. Most of this money funded research of interest to scientists, with negligible amounts devoted to integrating research with policy options. Little cost effectiveness analysis was conducted, nor were impacts of pollution beyond acid rain analyzed. In consequence, acid rain policies were effectively drafted without scientific input.

A similarly narrow focus characterizes atmospheric modeling, which relates emissions to actual air quality. Most models use emissions inventories, meteorology and knowledge of atmospheric chemistry as inputs, and yield information about resulting air quality. Typically these models deal with one phase, either gas or aerosol, and serve as a means for setting the emissions to attain a given air quality goal. What we really want, Prof. McRae said, is a broader view that also analyzes control systems, incorporating societal goals and environmental impacts. Such an approach would incorporate the distinct economic and political processes that characterize the problem, and acknowledge natural variability and noise.

The purpose of modeling, Prof. McRae said, is to avoid experimentation. Without a model, the only way to evaluate and experiment with policies is to actually implement them and monitor the results. Modeling gives us a method to analyze responses to change without first needing to implement the policies. Modeled results can then be used to act as further input for the design of control systems. By using such an iterative method, the likelihood of implementing a successful control strategy markedly improves.

Integrated Assessments

Prof. McRae defined integrated assessment: "To understand and integrate the component parts of a problem with an overall objective to implement cost effective solutions over time..." Its three componentsanalysis, synthesis, and outreachmust each provide feedback to the others.

Analysis attempts to understand the problem from a multidisciplinary and historical perspective. With air pollution, this would consider the health issues driving the need for intervention, the scientific problems, assessment of previous efforts, the regulatory structure, interest groups, and identification of policy options.

How to characterize emissions, the role of new instrumentation, and new analytic tools such as inverse modeling are examples of some key scientific issues. Prof. McRae identified Tunable Laser Diode Spectroscopy as an example of a new technology that can provide better estimates of actual vehicle emissions. With better data, a better statement of the problem can be formulated. And, by incorporating new decision variables and different decision-making algorithms, new options and policy proscriptions can be devised

Synthesis assembles these separate pieces into a coherent and viable program. Evaluation and analysis of different aspects of the problem are incorporated into the design of new control strategies that can bring new technologies, regulatory structures and resources to bear on the problem. In this step, one of the goals is to reduce the uncertainty in the decision-making process by bringing different skill-sets to the issue. Some examples of research on regulation and control strategies at MIT include market- and incentive-based schemes, risk-based regulation in the presence of uncertainty, integrated regulation across media and trading mechanisms. The goal is to allow the process to be actively shaped by stakeholders so that the "victim" aspect of the regulatory process can be eliminated.

The goal of Outreach is the successful implementation of the strategies developed through analysis and synthesis. Outreach is designed to build community consensus for the regulation as well as to expand the number of people trained to make these types of decisions. The aim is to establish an educational and evaluation system so that the process can be improved and its effectiveness appraised. Technology can help here, allowing computer generated maps and animation to explain science to the non-scientist. Prof. McRae demonstrated an animated model used in Los Angeles as a way to explain pollution strategies.

Education must also be directed at scientists and policy makers. For the Mexico City Project, a number of educational programs have been proposed to increase the flow of human capital and knowledge between the United States and Mexico, as well as between the scientific and policy-making communities. Activities such as short courses, visitor exchange programs, and collaborative measurement campaigns could be pursued.

In addition to the direct outcomes of the integrated assessment, Prof. McRae expressed the desire to provide a neutral forum for discussion of policy issues, and to develop stronger relationships between the participants in these discussions. The Mexico City Project would have joint US-Mexico executive and advisory committees, and project management to support communication and collaboration. The focus would be cost-effective strategies for mobility and fuels, power generation, land use planning, and technology options. Scientific, technical, economic, institutional and social issues would be integrated by involving different groups, departments, and links with interdisciplinary programs.

In conclusion, Prof. McRae said that the project would be deemed successful if its methods can be used by other cities to combat the global problem of air pollution.

Figure 2-2. Emissions-air quality relationships

Figure 2-3. A broader viewmodeling as part of a control system

Presentation by Dr. Francisco Guzmán

The Mexican Air Quality Research Initiative (MARI)

The Mexican Air Quality Research Initiative (MARI) (1990­1993) project was an integrated assessment sponsored jointly by IMP and the US Department of Energy (Los Alamos National Laboratories was the primary participant representing DOE). Its aim was to go from a portfolio of control strategy options to a coordinated, effective strategy. The project was a typical science-oriented project, which was challenged to incorporate some integrated assessment aspects.

Elements of the project included monitoring, measurement and characterization studies oriented around ozone, and pollution modeling and simulation. For strategy options, MARI looked at cost and emissions impact, and included a linear optimization. By running simulations of strategies, researchers were able to add economic, social, and political factors to the decision analysis tree (Figure 2-4).

First, an objective analysis was performed: quantitative information with respect to each control option was established, including reductions and cost, and current vs. target pollution levels were identified. This information was used in a linear programming model. Later, a non-linear approach was used, which showed NO_x effectiveness to be worse when considered in terms of annualized cost for percent ozone reduction (Figures 2-5a, 2-5b, & 2-5c).

The decision analysis tree was based on decision theory technique. There were four branches, representing technical, economic, social/political/institutional, and environmental issues. Under each issue area, multiple attributes were assessed and assigned weighting factors based on subjective analysis by people specifically chosen for their expertise (see Figure 2-6).

No explicit health effects were represented in the decision analysis tree. Dr. Guzmán remarked that when the project began in 1991, scarce data were available on health effects in Mexico City, so the issue was reflected through the air quality index only. Later, the tree was modified by adding an explicit health effects branch, but no weighting factors were used.

Using this approach, only 37 control options had sufficient information for the methodology, and more than 30 were analyzed. Out of these, 21 were chosen for final grading.

Dr. Guzmán said that the five-volume report of the MARI project is available on the Los Alamos web site. These include the executive summary and four technical volumes. The last volume is the strategy evaluation. Dr. Guzmán concluded that the MARI project is the only integrated assessment project to assemble scientific, technical, and social/economic aspects under one umbrella.

Discussion Summary

The discussion addressed aspects of integration, evaluation, community input and public perception, and how to accommodate social criteria, as related to the MARI project, to Mexico, and to integrated assessments in general. Comments on the goals of the Mexico City Project reinforced the need to focus on identifying barriers and producing a set of issues for research and examination, rather than trying to formulate a comprehensive and immediate solution. The MARI project provided some perspective on conducting large, integrated projects. Asked what he would do differently if he had the whole project to do over again, Francisco Guzman replied that he would keep the expert panel meeting as a means of maintaining dialogue between diverse groups.

How to address "soft" issues was the subject of much discussion. MARI is a specific example of an integrated assessment based on optimizing multiple weighted objectives, but this is only one model. Another might approach it as a "coordinated assessment" rather than a mathematical optimization around one variable. One suggestion was to think about integrated assessment as a mechanism to produce sets of issues that can then be evaluated from different perspectives (political, economic, scientific, etc.), providing an appraisal of the advantages and disadvantages for different sectors of society. With the understanding that there is no single way to view the data, analysis should serve to spark discourse and feed the broad debate rather than attempt to provide a final answer.

Bringing in perspectives from different sectors also helps to broaden the debate of control strategies, as does looking at approaches used in different countries. For example, one means of addressing air pollutionand at the same time other problemsis to build industries and create jobs away from major cities in order to stem the tide of growing urban population. Expanding the view beyond technical strategies stimulates "out of the box" thinking about solutions that might involve, for instance, land use planning or mobility strategies. The integrated assessment will get to the broader issues by encouraging these ideas. Indeed, this project goes beyond dealing just with ozone (which was the sole focus of MARI).

The discussion addressed how to integrate other issues, such as particulates, climate change, land use, etc. Global warming is one area in which there is an understanding that complicated problems cannot be solved solely by one discipline, but need a broader view. However, there is no clear method to accomplish this, and limitations exist given the different institutional frameworks for addressing local, regional, and global issues. For example, in Mexico City the emissions inventory is currently coordinated by the Metropolitan Commission, but the federal government keeps the inventory of point sources, and there is a lack of coordination between the two agencies. The national greenhouse gas emissions inventory is produced by a mixture of bottom up and top down, but has many holes. At a high level of abstraction (e.g., using GNP weightings to parcel national emissions to particular areas), the inventories become very inaccurate. The lack of reliable emissions inventories that are robust enough to be used for different levels of analysis is a barrier to integrated assessment. How to address these limitations and barriers would be appropriate questions for further research.

However the assessment is constructed, we need to be thoughtful about how to handle the social dimensions. Criteria are often intangible and not measurable, and there may not be enough information to quantify the social aspects of the problem. An alternative model might allow accounting for social issues without actually quantifying them. In reality, tradeoffs between criteria such as fairness, equity, and cost effectiveness are a significant factor in the perception of and actual implementation of policies. The risk is that policy makers make decisions about these tradeoffs implicitly, without taking all of these factors into account unless there is an ongoing panel of experts making these intangibles explicit and keeping them in the debate.

One experience of the MARI project highlighted this. As part of the decision analysis, the project provided a forum for policy makers at the highest level to exchange ideas and discuss weightings for evaluation. Closing the refinery near Mexico City was never even considered as a viable option because it was too expensive, and cost was heavily weighted. Yet the President of Mexico subsequently closed the refinery unilaterally, which yielded a very positive effect. Obviously, the "experts" got the weighting wrong, and overlooked the priorities of the most important personthe President. The involvement of the President gave credibility to the action and forced others to think about such possibilities. Participants still thought it was useful to have representatives from different sectors exchange ideas, but the outcome in this circumstance illustrates one of the dangers of relying exclusively on exercises that reduce everything to numbers and rankings.

Another problem with expert weighting schemes and optimization techniques is that even with a reliable set of input data, results can be invalidated once the community learns of the subjective weightings used and where they came from. Education needs to happen early in the process so that public perceptions are not at odds with scientific findings.

One lesson is that there are no "right" answers. Rational analysis is a useful tool but it must be recognized that any weighting scheme represents a particular group. In reality, politics requires that decisions be made in the context of different groups with different priorities. A good policy process should have feedback loops to integrate different perceptions into the analysis, and should recognize that even given the same science, the answer for one city might not be the same as the answer for another.

It was pointed out that how different communities (government, scientific, public) construct the problem frames how they approach potential solutions. This construction of the problem is crucial; the solution is not just a technical matter of scientific findings, but requires putting them into practice in the political, economic, and social context in which the problem is framed. Even in scientific communities there isn't consensus, so it is particularly important to take different forces and priorities into account.

There was general concern that integrated assessments might not adequately take into account community input, and discussion about the need to involve the community in addition to including experts from different sectors. The MARI project included a public acceptance telephone survey, but it was minor in the context of the whole project. Some cited the lack of government efforts to involve the community during the developmental phase of programs and policies as a problem based in Mexican culture. Many comments reinforced the importance of taking public opinion into account better.

It was also pointed out that community outreach is important in order to get politicians to fund inventories and monitoring programs. Politicians need to understand the problem so that they can buy into a potentially difficult or costly solution, and public support is important to get resources allocated. Community outreach should happen all along the process of generating data and developing solutions.

The role of public perception was discussed as an important but complicated issue. People get information in different ways and many don't really understand the problem. For example, many ordinary people in Mexico City think they can smell and see ozone. Most of the information they get about air pollution comes from mass media, but how do the media deal with these issues? In general, they are not educated about air pollution either. Even considering what people learn in school, the level of knowledge is low. Given the lack of opinion polls assessing what people understand, we may be guessing when we refer to people's perceptions. For instance, if Mexico City were classified according to the scheme in the US Clean Air Act Amendments of 1990, it would be a "severe non-attainment" area, which is given 20 years to develop a solution. But ordinary citizens don't realize that this is how complicated and difficult the problem is. They expect it can be done sooner, and they want the government to fix the problem without making them leave their cars. To address these issues, some suggested there be an effort to gauge what people really know. And, since the media do educate the public, one service the project can provide is to make sure that the media report it correctly.

Participants recognized that the job is not done once policies are implemented, and discussed aspects of evaluation. MARI made a general assessment of the control program (the city government fully implemented all of the strategies suggested in the MARI project as well as some additional measure that were not originally assessed). The initial assessment of the control measures indicated a 10 to 20 percent reduction in peak ozone events relative to 1991 levels.¹ A similar reduction was observed, indicating the assessment was correct.² However they didn't evaluate the performance of specific strategies. For instance, emission reduction goals were based on all of the options being fully implemented, but somelike having all cars fitted with catalytic convertershave not happened yet. Strategy evaluation requires a good emissions data, and evaluation of the emissions inventor itself was also discussed. Older emission data had a lot of uncertainties, but now the inventory is better.

Evaluating implementation and effectiveness of specific strategies would yield useful information. Yet even in the US little evaluation is performed. Although Los Angeles has spent large sums of money on control, relatively little has been spent on analyzing trends or assessing the effectiveness of its programs. It would be informative to compare Mexico City's progress to Los Angeles, where there are more people and more money devoted to the problem. In general, evaluating whether control strategies are working is very important and should have more resources devoted to it. Coming up with some methods to better compare the effectiveness of different programs would be a good contribution that the project can make.

In sum, participants acknowledged that there are no magic solutions, and successful strategies need time and effort. The project's intent is to contribute to the process. Evaluating what has been done in the past is important, as is educating people around this issue. The integrated assessment should deal with how to interact with the media and craft a strategy for public participation. The cultural basis for the issue, particularly with respect to public participation and decision making in Mexico, needs to be better understood. Finally, the issue of trust is very important. This project has no political stake. It aims to be neutral, and to provide a discussion forum which is neutral, and so has tremendous possibilities.

Footnotes

1. It was pointed out, however, that even if emission reduction goals were fully realized, it would not be enough to achieve the standard.
2. For example, typical IMECA values (for peak events) in 1991 were between 280 and 290, and in 1995 they were around 240 to 250.

Moderator: Adrián Fernández, Instituto Nacional de Ecología
Speakers: Gustavo Olaiz, Secretaría de Salud and John Spengler, Harvard

Dr. Adrián Fernández opened the session by remarking that the 1990 PICCA plan had more than 30 actions, only one of which had a health componentan epidemiological surveillance program that in the end was not implemented. In fact, at the beginning of the present presidential administration, according to Dr. Olaiz, the official position of the government's Health Ministry's was that air pollution in Mexico City had no effects at all on health.

Presentation by Dr. Gustavo Olaiz

Dr. Gustavo Olaiz began his talk by noting that the air pollution-health connection was long in coming. He recalled the time not long ago when researchers studied the benefits of ozone, drawing their support from the fact that bacteria die from ozone.

Surveillance Studies

According to Dr. Olaiz, the principal causes of Mexico City's air pollution are:

• the roughly 4 million vehicles, of which many are old;
• emissions from industry, particularly in the northern section;
• overpopulation (which he considers to be the most important factor); and
• deforestation.

As Under-Secretary of Environmental Health, Dr. Olaiz stated that the basic objectives of his Directorate were to (1) promote public participation to reduce health effects, (2) create coordination mechanisms for dealing with environmental emergencies, and (3) avoid exposures in the population.

To demonstrate to other authorities that this is a serious problem, health researchers began an epidemiological surveillance program to monitor daily acute health effects associated with air pollution. Currently, they are also conducting controlled perspective studies: for example, monitoring school-age children to as sess chronic effects. This research is being conducted in coordination with Johns Hopkins and other institutions.

Describing the surveillance system, Dr. Olaiz said they are able to capture information from all health clinics and hospitals thanks to Mexico's comprehensive national health system. They are also conducting ongoing surveillance of households, schools, etc. To establish a geographic program, they established surveillance systems in selected areas in the vicinity of environmental monitors (see Figure 3-1).¹ They survey hospitals and collect information on everyone inside a two-kilometer area surrounding the monitor, using a census of homes to conduct actual visits to the houses in order to evaluate respiratory symptoms. According to Dr. Olaiz this is the biggest surveillance program in the world, collecting information from 600,000 people in 180,000 households.

Figure 3-1. Environmental health surveillance areas

Ozone

Many of ozone's more serious health effects come from its impact on lung membranes. Ozone also affects lung secretions, reduces tracheobroncheal diameter, and is thought to impair immune responses. Exposure results in a significant reduction in breathing capacity, which can cause severe problems for those with asthma or severe or chronic respiratory disease. Also at risk are people who work outdoors.

Describing some of their findings from their health studies, Dr. Olaiz reported that at base ozone levels, about 8% of the population experience symptoms. At 240 IMECAS, this increases to about 15%. At 240-260 IMECAS, 25% of the population experience symptoms. As ozone levels increase, symptoms increase from eye irritation to tear secretion, headache, sore throats, and respiratory difficulty.

Based on the cost of direct health problems alone, Dr. Olaiz estimated that million is spent on direct health costs for each contingency episode above 240 IMECAS.

Figure 3-2. Symptoms at different ozone levels

Particulates

Dr. Olaiz went on to discuss data for the health impacts of PM₁₀ (Figure 3-3). These studies are fairly new, he said. For PM₁₀ they found similar results to ozone, but with a lag of 7-10 days between exposure and health effects (3-5 days for children), making particulates more difficult to study. Though the media are focused on ozone, particulates are also a significant problem. The worst situation, he pointed out, is when ozone and PM₁₀ levels are elevated at the same time (Figure 3-4). He said that combined high levels of ozone and particles is new.

Figure 3-3. Symptoms at different ozone levels

Figure 3-4: Symptoms for combined levels of ozone and particulates

Initial studies show that a 10 mg/m³ increase in the ambient concentration of particulates results in a 0.5% increase in mortality. The problem with the models, however, is that they are linear. Dr. Olaiz said there is a need to work on better understanding the dose-response relationship.

Finally, he said that PM₁₀ and ozone aren't all we need to be concerned about. There are unpublished findings that when ozone levels start to rise, symptoms start earlyeven by a full day. There are many more poorly understood pollutants in the air. Health researchers need to understand what is happening, beginning with the toxicity of different pollutants.

Dr. Olaiz concluded his presentation by asking what's needed by this group. Health is a good motivator for getting something to happen, he said, so the information from these health studies is important. There is a need to assess exposure better; ambient monitoring is useful to understand what a typical day looks like, he said, but personal exposures are different. They are currently doing various long-term studies centered on personal exposure monitoring, including a three-year study of healthy adults, a five-year study of asthmatic children, and another study looking at school-age children, which has been in progress for three and a half years.

Presentation by Professor John Spengler

Professor John Spengler noted that Mexicans have long-term monitoring data, and a sense of the trends and spatial distributions of pollution, which is more than the case for many cities. Ozone in Mexico City is the highest he has seen in the world, he said, while particulates, though also a problem, are not as severe as in Beijing or Delhi. He pointed out that Mexico experiences forest fires and warm dry spells where wind speeds drop by a factor of two for a whole year. These environmental and meteorological events need to be incorporated into de-trending the data.

With respect to monitoring, he asked whether the right compounds are being measured. Instrumentation also plays a crucial role in the validity of the data. He asked if the right instruments were being used, and used correctly. In the case of PM, for example, we don't even know what component of particles we should be measuring. All measurements are approximations, he pointed out, and researchers should look for consistencies in the dose-response relationship. He referred to the Los Alamos/IMP/DRI study examining particle composition and source factors, and asked whether this is enough. Perhaps there is a need to institutionalize these studies and expand what's monitored, he suggested.

Discussing population exposures, Prof. Spengler explained why exposure data are needed even if there is so much ambient monitoring. There is a need to be comprehensive with respect to risk assessment and exposure analysis, as well as a strong need to disentangle signals on the health effects side. There may be conflicting sources masking which substances are actually causing the effects. For instance, indoor (cooking) and outdoor (transportation) combustion both put out NO₂, but exposure scenarios aren't well understood yet. There is a need to measure exposures in order to get at status and trends in subpopulations. About ten years ago, Adrián Fernández did a CO exposure study

on various transportation routes and compared his results to ambient monitoring data. Paulina Serrano, a Harvard Ph.D. student, is conducting a similar study now using personal monitors to track exposure to VOCs and CO. They have found that during the commute period, CO exposures are much higher than would be anticipated by the ambient monitoring data alone. Therefore, the epidemiological impacts might not be directly correlated to ambient concentrations.

These studies are just a beginning, as they only look at respiratory symptoms and cardio-pulmonary impacts. An expanded analysis should consider exposures in a more coordinated way. Shifts in behavior patterns (e.g. by commuters) have an impact on exposure to different sources as well as the production of emissions. This needs to be understood from an economic and sociopolitical point of view, not just a scientific one. For example, a study might focus on combi (taxi) driver exposures. Such a study could also be helpful in influencing their behavior and generating political will. Another study might consider exposure on schoolteachers. In general, Prof. Spengler said, it is important to bring in other sectors, particularly agriculture and construction. The forest fires illustrate the impact agricultural policy has had when combined with dry weather. In the construction sector, design and building codes and the use of air conditioning are also relevant.

Initial studies indicate a 6% change in mortality rates given a 10 mg/m³ change in PM_2.5. This corresponds to roughly 8 respiratory deaths per day in the neighborhood being studied. Research is beginning to look at mechanisms of cardiovascular effects. Changes in blood viscosity and heart arrhythmias are being linked to particulates. Asthma, an immunological disease, is also an important indicator. Recent evidence elsewhere shows that ozone/NO exposure worsens the effects of exposure to allergens.

For an epidemiological study in Mexico City, Prof. Spengler proposed a longitudinal study of freshman coming to UNAM from other parts of the country. He said this group could be used to study housing exposures, track illness, development of allergies, etc. in a group newly exposed to Mexico City pollution.

Referring to the cost figures presented by Dr. Olaiz, Prof. Spengler said that million per episode is a huge amount, but if costs were integrated under the rest of the curve (capturing health effects from exposures at lower levels as well), the amount would be enormous. Generating this information could add a great deal to the political discussion.

Finally, Prof. Spengler described the experience of the Netherlands. In the mid-1980s the Dutch government commissioned a study of the state of the environment 25 years into the future given then-current trends. The image presented served as shock therapy to the nation, he explained. Everyone became informed with the help of a strong image of what they didn't want. This strengthened political forces sufficiently to generate powerful legislation across all sectors. Scientific integrity and enforceability were essential. Professor Spengler said that the Dutch model could possibly serve as an example of what could be done to inform policy makers and the public in Mexico.

Discussion Summary

Four years ago, public authorities were reviewing what level should be considered an "episode," with a strong interest in setting the standard so as to limit the number of episodes. Different institutions were involved, but the complicated discussions only came to a close when health officials weighed in with data showing the effects and costs of air pollution on human health. Though the influence of health officials on air pollution policies is real, it was noted 240 IMECAS was chosen as the contingency level, while the goal of health officials was 100 IMECAS.

Health costs incurred at contingency levels of pollution focus on short-term solutions; the context of this project, however, is to consider the long-term. For this, more comprehensive cost figuresshowing costs from health impacts experienced at concentrations below contingency levelswould be very useful. It was noted that not all people do the same calculus; some focus on economic issues, some on politics. Also, determining how much a life is worth for economic analyses is a very difficult issue.

Public opinion and the role of education was discussed. In Mexico City, the environmental agenda competes with other agendas (security, unemployment, etc.) A recent Mexico City newspaper survey found that the most pressing problem for the population had shifted from security to pollution. There was a suggestion that we have been too successful in raising the alarm against air pollution, at the expense of other environmental problems like water quality. Nevertheless, there was general agreement about the need to educate people that air quality is part of their well-being. Bad public relations in this area have led to a defeatist attitude, as evidenced by the article in that day's New York Times, "A Fatal Case of Fatalism," which discussed air pollution in Mexico City. The example of cancer was raised to suggest alternative strategies. The American Cancer Society recently started a program of "good, better, and best news" to overcome the defeatist attitude by providing people with hope and focusing their actions.

It was also noted that educational efforts should attempt to condition people to the value of sacrifice. In this respect, it's helpful to recognize two different kinds of democracy: one that looks for the best solution for society as a whole (the Scandinavian design) and individualistic democracy, where each individual's stake is equally valid and the result is often paralysis.

The issue of exposures vs. ambient pollution concentrations was further discussed. Participants agreed with the presenters that we should be looking at how to reduce human exposures over the long term, not just reducing source emissions or ambient concentrations. Risk assessment is the link needed to target reducing human exposures.

The topic of assessing exposures raised the issue of confounding factors, which generated a few questions. Indoor ozone exposures are dramatically lower than outdoors, and this can confound effects. This is why exposure assessment is important. Researchers are able to control for meteorological variables and other pollutants on the "dose" side of the equation; they were asked how they control for other causes of respiratory diseases, such as ordinary colds, on the "response" side. There is a need to disentangle various health problems, especially considering that most schools and homes in Mexico City are not heated and people blame any symptoms they have on ozone. (It was noted that the city is "ozonized;" everyone knows when ozone levels are elevated and when they "should" feel sick.)

Though particles are routinely monitored, and contingency measures triggered at certain levels, this approach doesn't account for varying PM composition in different areas of the city. Other complicating factors in using health research to set standards are (1) standards are set for one pollutant at a time, which doesn't necessarily address the effects of multiple exposures; and (2) standards are set to protect the majority, without considering subgroups. (Children breathe more air and at a faster rate than adults, for example, so their exposures are typically higher.)

Participants discussed how to reach decision makers, suggesting we focus on those issues with opportunities for the biggest impact. We should first educate the publicperhaps focusing on a study of combi drivers or infants, as suggested earlierin order to mobilize popular demands for action, then target a small but powerful group of decision makers (the President, the finance minister, regulators including Congress).

Footnote

1. The monitoring stations and study areas in the city are: Xalostoc (northeast); Tlanepantla (northwest); Iztapalapa (southeast); Centro (downtown); Plateros (southwest); Pedregal (southwest); and Netzahualcoyotl (east).

Moderator: Ralph Gakenheimer, MIT
Speakers: Richard de Neufville, MIT; Arnold Howitt, Harvard; José Luis Lezama, El Colegio de México and Víctor Urquidi, El Colegio de México.

Professor Ralph Gakenheimer opened the session by stating the objectives as follows:

• to review information presented in earlier sessions;
• to determine the optimal means of influencing public policy regarding environmental concerns in Mexico City.

Presentation by Prof. Richard de Neufville

Professor de Neufville stated that science is not enough to address the complex issues involved in cleaning the air. He cited the US experience with leaded gasoline as an example. While the health effects of leaded gasoline were well understood, and the technology available to use unleaded gasoline, US implementation of controls lagged significantly behind. Prof. de Neufville suggested that integrated assessments such as the Mexico City project might teach us ways to quicken and improve this public policy process.

Prof. de Neufville introduced the Technology and Policy Program (TPP). TPP is a unique educational venture at MIT, based on the premise that addressing multi-disciplinary problems requires political, social, legal, and economic understanding. Given the lack of professionals who can bridge these disciplines, TPP's goal is to educate the next generation of professionals that can take a long-term view in analyzing complex, multi-disciplinary problems. He contrasted TPP's approach with the usual way of training engineers with little understanding of social science, and social scientists with little technical training.

Prof. de Neufville outlined three TPP premises:

• There is no "right" answer. No purely "technical fix" exists for these problems; negotiation is an important part of the process, and to make effective policies, scientists and policy makers need to build and maintain constituencies. A feedback loop for exchange of information with society is essential.
• Uncertainty must be managed. There will always be unknowns. Future demographics and social conditions are impossible to predetermine, so we need to develop approaches that aim for a strategic position in anticipation of changes, not unlike chess.
• Professionals need to be trained across disciplines. A need exists for people who can take technical knowledge into the political/economic contexts in which policies evolve. Negotiation is critical between the actors working towards a solution. Not every party is going to get everything it wants. Compromise is essential.

In closing, Prof. de Neufville encouraged institutions involved in the Mexico City Project to use TPP as a resource, and invited Mexican students to take advantage of Masters, Ph.D., post-doctoral and other educational opportunities at MIT.

Presentation by Dr. Arnold Howitt

Dr. Arnold Howitt presented an overview of US transportation and land use policies aimed at reducing mobile-source emissions. From 1970­1995, the number of vehicle miles traveled (VMT) increased over 100%, while total emissions from various pollutants decreased. This was due to policy interventions in three areas: (1) technology mandates; (2) regulation of land use and transportation structure; and (3) regulation of individual behavior.

Technology mandates

• vehicle emission control systems;
• fuel formulation; and
• alternatives to the internal combustion engine.

The US has been fairly successful in adopting and imposing standards, with emission controls and fuel formulation accounting for most of the US mobile source emission reductions to date. This is in part because these regulations target a small number of large corporations, making the regulations enforceable and politically feasible (despite industry's resistance). Public support has been strong, empowering elected officials.

As fleet turnover takes approximately 10­14 years, policies targeted at new cars are also phased in over this time frame. Dr. Howitt commented that these policies have been the most cost-effective ways to reduce mobile source emissions.

Regulation of land use and transportation infrastructure

• Integrated land use/transportation/air pollution planning, including system and project-level emission analysis
• Regulation of public infrastructure investments, such as highways and transit systems
• Regulation of land use, such as growth management

Dr. Howitt stated that these policies are extremely difficult to impose and implement. Competing environmental and economic factors are involved, as well as individual lifestyle choices. Furthermore, US decision-making structures dealing with land use are highly decentralized, which makes it difficult to push for integrated planning and regulations.

While these structures are more centralized regarding transportation, it is difficult to make a large impact on travel patterns in mature metropolitan areas as new development is only a small percentage of total development. As a result, policy instruments targeting land use and transportation infrastructure are best considered for a long-range time horizon of 30­50 years and beyond.

Regulation of individual behavior

• Inspection and maintenance of in-use vehicle emission control systems;
• Transportation system management (TSM) policies to improve traffic flow and improve efficiency on existing transportation networks;
• Non-restrictive transportation demand management (TDM) to promote non-single-occupancy vehicle (SOV) transportation: mass transit, high-occupancy vehicle (HOV) highway lanes, and intelligent transportation system applications, as well as voluntary carpooling, trip reduction, and telecommuting;
• Restrictive TDM, such as financial disincentives or regulatory constraints, including transportation pricing controls, restrictions on parking, exclusion of SOVs, and mandatory trip reduction and car pooling.

Vehicle inspection and maintenance policies have aroused substantial political reaction, which has frequently been overcome. TSM policies and non-restrictive approaches have had relatively minor impact on U.S. emissions. In Houston, intelligent highway and HOV systems have resulted in VOC reductions of just 0.5 tons per day. Though restrictive TDM policies have the potential to reduce emissions significantly, they are politically difficult to impose and regulate. They affect a large number of individuals and firms, and tend to require a substantial degree of voluntary compliance due to limited enforcement possibilities. Also, as vehicles become cleaner, the cost effectiveness of strategies aimed at reducing VMT is diminished. As a result, restrictive TDM policies have not been widely adopted. Singapore is one of the few countries to implement such policies successfully, due to its particular geographic and enforcement context.

Presentation by Prof. José Luis Lezama

Prof. Lezama noted that the Mexican government has introduced various policy programs to address air pollution in Mexico City since the early 1970s, with intensive planning activities beginning in the 1980s. Various approaches have been tried: improving fuel quality, abating traffic problems, upgrading public transportation, controlling emissions from automobiles, industry, and services, and developing educational programs. Three programs were of particular significance:

• Programa Coordinado para Mejorar la Calidad del Aire en el Valle de México (PCMCA), 1979.
• Programa Integral Contra la Contaminación Atmosférica 1990-1995 (PICCA), 1990.
• Programa para Mejorar la Calidad del Aire en el Valle de México (PROAIRE), 1996.

Since the introduction of PCMCA, Mexico City has experienced major environmental, economic, social, and political changes, which have changed both the nature of the air pollution problem and the suitability of various policy instruments. The policy programs, however, have not been adapted to address these changes, and are hampered by limited analysis of physical and technical characteristics of pollution and the absence of realistic consideration of social and political aspects. He attributed these limitations to the authoritarian nature of the Mexican system, which is not sufficiently open to input from the scientific community. Citizen participation in the policy process is also limited, which negatively influences the citizens' perception of the effectiveness of government programs.

Prof. Lezama argued that proposals for action lag behind diagnoses of the problem. For example, PROAIRE established that transportation and urban development were key factors influencing air pollution in Mexico City. However, PROAIRE did not outline any structural reforms to change the modal distribution of the public transportation system, nor to address interest groups such as those that own or operate minivans and small buses.

The government's limited action may be due to the low level of public awareness and understanding. The large distance between the citizens and the government also makes it difficult for the community to mobilize its efforts towards suitable solutions. This point underscores the importance of education and awareness raising among the public and within the government.

Further, citizens believe environmental issues are less critical than security, unemployment, and poverty. Prof. Lezama suggested that if the public were to become more aware, they would be more supportive, but he also warned that the public may not be willing to pay for a cleaner environment. Also, air pollution control may alter power relations among agencies by requiring redistribution of costs.

To increase their influence on policy, Prof. Lezama suggested that environmental agencies, whether local or metropolitan, build an institutional framework along the following lines:

• a division for policy to elaborate environmental options;
• a division for sectoral integration, to negotiate environmental criteria between sectors. Environmental policies of different government sectors must be integrated, and criteria established to guide the actions of different public agencies;
• a division responsible for monitoring implemented policies;
• an environmental ombudsman, to provide outreach to citizens in order to better enforce law and norms.

Prof. Lezama finished by elaborating on the need to integrate various government sectors regarding their environmental policies. Public agencies need to be forced by law to put environmental criteria into actions. Environmental authorities should push for the legal footing and political will needed to bring environmental programs and principles to other sectors whose actions are critical in terms of environmental impact. There is also an urgent need to create horizontal linkages among all the sectors that impact the environment.

Presentation by Professor Victor Urquidi

Prof. Urquidi began by saying that little environmental improvement can be expected without structural change. He suggested that Mexico's current government is not strong enough to consider long-term consequences, and as a result focuses on symptoms rather than underlying causes. To illustrate the lack of strategic planning, he cited Mexico City's transportation system. Access to the city is a bottleneck from all di rections, in part because interurban traffic is mixed with local. Other factors are delayed construction/repairs and mixing of freight and passenger transport. Often freight from one part of Mexico to another passes through Mexico City because of limited alternatives.

Mexico's 1994-1995 economic crisis increased social and economic inequalities including education, allowing little flexibility in budgetary policy, and conditions unfavorable to investment. According to Prof. Urquidi, the North American Free-Trade Agreement (NAFTA) has led to regionalized development (Mexico City, border regions) that doesn't spread easily to the rest of the country. Under the current political conditions, the private sector has little interest in addressing environmental problems, and it is difficult to persuade them to take a long-term view, as there is no clear development policy from the government. Instead, the market dominates. He pointed out that factories in border regions have multiplied since NAFTA, but that opportunities for globalization mean little to those regions left behind. He argued that NAFTA has imposed an American economic view (less government is better) that may be inappropriate for Mexico. In Mexico, decision-making is centralized, hence little opportunity exists to air views in conflict with the centralized government. He expressed concern that the government is emphasizing automobile production and sales in response to the economic crisis but to the detriment of the environment.

The media plays a critical role, according to Prof. Urquidi. Radio, TV, and newspapers fail to provide easily understood environmental information, partly because the media are themselves not well informed. He also stated the importance of including considerations of other cities and regions outside of Mexico City and the Metropolitan district into cultural and economic policies because the Mexico City Metropolitan Area is so important for the country as a whole.

The role of civil society, he said, is to articulate how local needs can influence policy. Given current economic constraints, it is difficult to accomplish this. Prof. Urquidi suggested that the Mexican government should be more interventionist and more concerned about equality and quality of life issues, which have largely been sacrificed in search of foreign investment. In summary, the key questions for the metropolitan area are whether it will be less industrialized and more service-oriented, and if public transit will be improved.

Prof. Urquidi concluded his presentation by offering his perspective on research priorities to improve the effectiveness of air pollution policy in Mexico City:

• Consideration of emission of pollutants from surrounding regions and the effect of the Popocatepetl volcano in evaluating the air quality in Mexico
• Effect of open air defecation and its incorporation into suspended particulates on air quality, integrated with water and public health analysis
• Comprehensive study of public transportation systems in Mexico City, including management and traffic route efficiency analysis
• Analysis of fuel consumption in transportation and non-transportation sectors
• Study of political and social factors that influence the public transportation system
• Assessment of the car culture, including private- and public-sector fleets, maintenance practices, and other policy instruments to influence individual behavior
• Financing of cars in Mexico City
• Policy making and media relations
• Policy coordination among different government agencies

Discussion Summary

There was general agreement on the need for more dialogue between different government agencies. It was noted that during the latest round of air pollution policy reformulation, SEMARNAP officials were unable to get input from the Ministry of Finance. As Mexico becomes more politically diverse, this poses a challenge that would be normal in a democratic society but is new in Mexico.

There was also discussion of Mexico's strengths in analysis vs. implementation of policies, and the lack of strategic planning and integration in the transportation sector. It was noted that Mexico tends to adopt US policies without regard for their appropriateness; e.g., US fuel standards are largely formulated to alleviate air pollution problems in Los Angeles, where a central fuel issue is sulfur content. While reducing sulfur content in gasoline greatly reduces emissions from newer vehicles, it is unclear if this costly strategy is appropriate given Mexico's much older fleet.

Participants addressed the role of non-governmental organizations (NGOs), the church, and the private sector. At present, NGOs are fewer in number and less scientifically informed in Mexico and tend to be combative. However, with better education and informa tion, there is potential for them to enter into constructive dialogue. Mexican religious leaders have generally not been attuned to environmental problems. As for industry, the current level of awareness and involvement is considered inadequate. This may be due to the historical hostility between industry and government. Large companies have become more aware of air pollution and the need to implement cleaner technologies. Small and medium sized enterprises, on the other hand, tend to have less capacity, and may not be aware of regulations. The maintenance level of corporate cars is also quite low, contributing to the air pollution problem. Policies and programs to address industrial pollution need to distinguish different levels of awareness and capacity. Active partnership with the automobile industry may be warranted for this project.

The link with the global environmental issues was emphasized. There is a strategic opportunity to work on both issues if the link can be made explicit. The Mexican government may accept more stringent GHG emission limits as it faces international pressure. Transportation policy is crucial for both urban and global pollution issues, and there needs to be a policy shift toward more investment in public transportation to change mobility. This project could consider the feasibility of pressuring the small number of decision makers with large decision-making authority by presenting them with some win-win solutions that integrate the urban air pollution issues with other problems such as congestion and climate change.

The Moderator presented the following preliminary summary of this section:

• Public education is important, and potential roles of NGOs should be further explored.
• There should be long-range, strategic policies that address behavior.
• There is a need to influence behavior and consider cultural elements in the analysis of policy and context.
• Possible policy consequences must be analyzed.
• Uncertainty is recognized as having an important role in policy making.
• A feedback system from society (and the skill to do this successfully) needs to be established.
• Some policies go in and out of favor, such as land use planning.
• Mexico has a maturing policy making system.
• Relating environmental issues to other priority issues, such as congestion, should be further explored.

Moderator: Telma Castro, Universidad Nacional Autónoma de México
Speakers: Mario Molina, MIT; Marisa Ruiz, Instituto Mexicano del Petróleo and Graciela Raga, Universidad Nacional Autónoma de México.

Presentation by Professor Mario Molina

Professor Mario Molina raised a number of questions to open the session:

1. Could particulate matter (rather than ozone) be the primary cause of health impacts?
2. Aside from what is already monitored, what else would be interesting or worthwhile to monitor, that might give us insights into the problem?
3. What are the relative effects on health of indoor vs. outdoor pollution? What exposures result from such activities as cooking and driving?
4. How good are current models to assess control programs? Do we have the right data for these models, and what is the quality of the data (emissions, measurements, reaction rates)? How useful are models fine-tuned elsewhere (esp. in the U.S.) for application in Mexico, and how can we test these models in Mexico?
5. What is the specific situation in Mexico City? The ambient atmosphere appears to be hydrocarbon rich, which suggests that NO_x controls would be more effective, but some results seem to contradict this. What is known about hydrocarbon speciation?
6. How much of the PM is secondary? How do particulates influence gas phase chemistry? How do particles age in the atmosphere? Do they become more acidic? More hydrophilic?

Presentation by Dr. Marisa Ruiz

Dr. Marisa Ruiz offered an overview of the work already done on air pollution in Mexico City, and of research underway at IMP.

• Measurements since 1986 show that overall NO_x concentrations have shown little change, but that NO_x to the northeast and center of the city is slightly increasing, and slightly decreasing southeast. The center has the highest readings.
• Measurements from IMADA­AVER in 1997 show that VOC concentrations are highest in the center of the city. At all sites, paraffins make up roughly half the measured organics, although speciation varies in different sectors of the city.
• Measurements of VOC concentrations from 19921997 show a decreasing trend and higher concentrations in the spring than in winter.
• Smog chamber experiments at IMP were used to make ozone isopleths, which can be used to estimate the effects of changes in NO_x and hydrocarbon emissions on ambient ozone concentrations. (The relationship between NO_x, hydrocarbons, and ozone is non-linear. Depending on where you are on the curve, VOC vs. NO_x reductions have different impacts.) They looked at three groups of conditions: low morning, medium, and high. Results indicate that NO_xreductions would be more effective than hydrocarbon reductions at reducing ozone, and they have suggested decreasing both.
• 1997 VOC speciation data indicate that alkanes (e.g. propane and butane) are more abundant than aromatics, and benzene concentrations are low.
• The measured ratio of ambient VOCs to NO_x in Mexico City is often in the range of 15­35, which is much higher than the ratio in Los Angeles (~8). The decrease in this ratio since 1993 is due to the reduction in VOC emissions.
• Emissions inventories from 1996 show that mobile sources account for a large fraction of emissions of hydrocarbons, NO_x, and total particulates.
• Large differences between emissions inventories over the past decade show the effect of changes in emissions over time, and also differences in the methods used for assessment.
• As an example of the emissions inventory, the IMADA project estimates that most of the ammonia emissions are from animals and sewage.
• Geographic Information System (GIS) mapping shows the daily spatial and temporal distribution of emissions in Mexico City, showing the effect of traffic patterns. GIS mapping has also been used, for example, to show the locations of gas stations in the city.

Presentation by Dr. Graciela Raga

Dr. Graciela Raga addressed two main topics:

Characterization of aerosols and trace gases in Mexico City

• Trace pollutants in the atmosphere come from primary emissions (CO, NO_x, SO₂), and secondary reactions of precursor emissions (ozone formed from NO_x and VOCs). Several measurement campaigns have been carried out to address concentrations of trace gases. Principal participants were RAMA (government), IMP, and UNAM (CCA & IGF).
• Total suspended particulates (TSP) have been measured in the basin for more than 10 years, with three years of hourly measurements of PM₁₀. Columnar concentration of optically active aerosol particles (radii from 0.01­10.0 mm) have been estimated for more than 30 years, using direct solar radiation measurements. Much less is known about size distribution (there are more than 10 years of records of surface size distributions measurements for particles of radii only from 0.003 mm to 0.5 mm) and composition of the particles (microphysical characterization), and this knowledge is needed for better modeling. There is also a need to understand optical characteristics, including extinction coefficients and single scattering albedo.¹
• Measurements suggest that aerosols in Mexico City are highly absorbent of solar radiation (suggesting a high elemental carbon content), which may affect local climate.
• Research/modeling issues: (1) Aerosol modeling efforts are underway but are limited by the availability of data. (2) There are good datasets for trace gases, but little research using these data. (3) There are good data for horizontal surface coverage but limited data for vertical distributions. (4) Other compounds must also be monitored. It is not clear that the substances now measured are the most appropriate to serve as indicators of health impacts or air quality.

Linkage between urban pollution and global climate change

• Modeling suggests a transport of gases to the upper troposphere and that the Mexico City basin cleans itself (to some extent) daily. Despite the mountains, the boundary layer is quite high (2 km), allowing pollutants to escape the basin.
• Export of gases and aerosols from Mexico City over a broader region may be important for climate. Are gases such as NO_x, ozone, and PAN transported outside the city?
• Primary gases such as CO, SO₂, and NMHC, while not greenhouse gases, may be useful as tracers of the urban plume.
• CO₂ is important with respect to global warming but no measurements exist for Mexico City.
• Ozone is an important GHG; is it exported, or created downwind from precursors?
• Little is known about the export of aerosols, how they evolve during transport. There are questions concerning their effect on regional radiative balance, aerosol-cloud interactions (and regional meteorology), and their role in regional photochemical forcing. Do primary particles play a role in the condensation of secondary particles as they are transported outside the basin? Some studies indicate that particles are larger at the top of the boundary layer. In particular, aerosols might affect the stratification of the boundary layer, decreasing vertical transport and therefore decreasing transport out of the basin.
• Regarding the interactions between particles and ozone, aerosols may decrease the radiation flux and therefore decrease ozone formation.

Discussion Summary

Some additional specific information was elicited as part of the discussion:

• During the forest fires in the basin, ozone concentrations were up, along with particles.
• The speciation of hydrocarbons is essential for photochemical modeling. UNAM has measured emissions from ten different industries/services, but except for gasoline distribution they don't have speciation data yet.
• The speciation of hydrocarbons emitted from refueling differs from speciation emitted in exhaust emissions.
• There are high concentrations of polycyclic aromatic hydrocarbons (PAHs) in PM_2.5. Studies carried out by Dr. G. Ruiz Suarez and others also show naphthalene, contrary to common wisdom, and higher concentrations of light aromatics in PM_2.5.

The speciation of hydrocarbons as it relates to fuel formulation and evaporative vs. combustion emissions was discussed. Proposed changes in the refining of PEMEX gasoline could alter the speciation of hydrocarbons. Since Mexico City has the strictest fuel specifications in the country, a lot of imported stock with high octane is used­about 10% at 93 octane (premium) and the rest at 87 octane (regular unleaded). Further changes in the city's fuel specifications are not anticipated.

Gasoline vapor recovery programs are now widespread in Mexico City. Following the US model, Mexico has progressed from Stage 0 (at gasoline distribution points) to Stage I (during delivery of fuel to gas stations) in 1994. Stage II (refueling vapor recovery) is underway. About 100 out of 400 gas stations in the area have operating Stage II vapor recovery equipment. While the requirement was that all gas stations would be equipped by April of 1999, it is projected that roughly 90% would install Stage II by 2000. It was noted that equipment manufacturers overlooked Mexico City's lower atmospheric pressure, and were claiming higher recovery rates than were actually achieved, which is about 85%.

Poorly maintained cars have 4­8 times greater emissions, with diesel vehicles being of particular concern; even EPA '94 type designs with sealed injectors are often tampered with within months of purchase. Some CNG and LPG vehicles have also been found to have worse emissions than gasoline vehicles because of poor maintenance. Part of the problem is that there is no culture of keeping vehicles well-maintained, and mechanics often have little training. In particular, few mechanics are capable of performing maintenance on diesel engines.

Diesel vehicles are suspected of being important sources of PM. There has been some direct and indirect measurement of soot in particles. An effort was conducted by IMP and DRI in 1997 (the IMADA-AVER program) to estimate carbon content of PM_2.5. IMADA measurements show a high content of elemental and organic carbon (~15%). The high absorption of light by small particles suggests a lot of soot. They also examined particles in an electron microscope and visualized the carbon structure of the smallest particles. These techniques, however, are not quantitative. A preliminary inventory of PM₁₀ sources was completed last year and vehicles (both gas and diesel) appear to be very important. Using DRI/IMP information to estimate the soil/dust contribution at 50%, the remaining half was estimated to be about 1/3 from gasoline vehicles, 1/3 from diesel vehicles, and 1/3 from industry. At the PM_2.5 level, the relative proportion from diesel increases, and the exposure potential is even higher.

Issues related to the use of LPG fuel were also discussed. Mexico City is unique because of the widespread use of LPG for cooking. Flames are poorly calibrated, so they might be an important source of carbon. While Mexico City gasoline consumption is 20,000 barrels/day, LPG consumption is 70,000 barrels/day. This is a higher proportion of LPG to gasoline than anywhere in the world, and emissions are not well understood.

The role of weather was brought up. 1998 was a hot year, yet the city saw a constant reduction in ozone concentrations. One study of 18 important ozone episodes at Pedregal (an area in the southwest of the city) noted a consistent wind direction of 185. The most important ozone episodes showed the wind coming from the same direction.

Considerable discussion addressed data quality and emission inventories. There is some concern about the quality of Mexican data. In Mexico, little quality assurance and quality control is carried out, possibly due to prohibitive costs. Data quality must be considered carefully, and it is important to quantify and reflect in the models any resulting uncertainty. Inventories of emissions are also problematic. US EPA methods for assessing emissions may not be correct for Mexico City. Inventories are easy to generate since coefficients are multiplied by economic activities, but there is uncertainty in these numbers. No studies have been conducted on these coefficients, and just last month such a study was cancelled due to cost. One way to improve data quality generally is to have more people looking at the data and doing research with the data, performing statistical analysis, etc. Another possibility is to begin to use inverse methods to work backwards from measurements to assess the quality of the inventory data. Today, there is better chemical specificity and methods to propagate uncertainty. There is a need to go beyond the standard reply that emissions are uncertain and begin to put bounds on those numbers.² This is true for GHG inventories as well as inventories of ozone precursors and particulates.

The connection between monitoring efforts and health effects was raised. For example, if particles are changing blood viscosity (as reported in the health effects session), what elements or compounds should be monitored?

Finally, the role of science was discussed. Three-dimensional modeling of particular air pollution episodes may not be the most appropriate method of assessing effects of changes in emissions from control programs. What other, possibly simpler, techniques could we use, and how reliable are these?

Professor Molina presented the following summary of this session:

• The reliability of existing emissions inventory in Mexico is questionable (as is often the case in the US). Ways to generate better data need to be explored.
• Vehicle maintenance has a large impact on emissions.
• Fuel reformation may also lead to significant air quality improvements.
• Diesel vehicles are probably large sources of fine particles; emission controls should be explored.
• LPG is used extensively for indoor cooking and heating. The corresponding emissions should be better characterized (there is information on the contributions to the hydrocarbon budget from LPG leaks from atmospheric measurements).
• The effects of changes in emissions resulting from various control strategies should be explored using appropriate modeling techniques.

Footnotes

1. Since March 1999 and for periods of 6­8 months (for recalibration necessities), IGF has established a collaboration with NASA AERONET Federal Network (AErosol RObot NETwork) through which a sun photometer was installed at the IGF building roof, forming part of a world network. Goals include the assessment of the basic optical characteristics and size distribution of the aerosol particles.
2. Greg McRae pointed out that Gustavo Sosa of IMP will be spending three months at MIT learning these tools and techniques.

Moderators: Stephen Connors, MIT

Mariano Bauer, Instituto Mexicano del Petróleo
Discussion: All Participants

Presentation by Mr. Stephen Connors

Mr. Stephen Connors opened the final "Bringing It All Together" session with a discussion of "Multi-Attribute Tradeoff Analysis," a technique developed at MIT to carry out complex research projects intended for diverse stakeholder audiences. Built around the early involvement of diverse stakeholders in the decision-making process, the aim is both to educate decision-makers and to ensure that results reflect the primary concerns of the various stakeholders.

He noted that most large infrastructure-related projects can be characterized as a combination of (1) complex problems, (2) dispersed solutions (many jurisdictions make it tough to communicate to decision makers), and (3) finite resources (time, money, people). The hazard of decision-making with inadequate input is illustrated by James Thurber's comment, "The conclusion you jump to may be your own."

He discussed the importance of helping stakeholders to understand and make better decisions, representing this "knowledge infrastructure" as a learning curve (Figure 6-1). At the low end is "problem existence" ("pollution is bad"). Next is "problem definition" ("the following pollutants are the primary sources of health problems and other impacts"). "Solution specification" looks for the most cost-effective and feasible ways to reduce those emissions, and, finally, "solution implementation" involves putting those solutions in place and monitoring the results. (These steps roughly map to the data, information, knowledge, and wisdom indices on the learning curve's vertical axis.) Unfortunately, decisions are often made in politically-charged venues focused on near-term outcomes, and are usually made prior to a consensus definition of the problem, let alone solution. The resulting scenario is shown in Figure 6-2, "Jumping to conclusions: jumping to solutions". "Wisdom," Mr. Connors said, is knowing the limits of your knowledge, adding that this is where issues related to uncertainty come in. The better one can define the problem, the easier it is to identify solutions. Outreach can get folded in. However, he said, the political dynamic often results in our "wallowing around the low end of the learning curve."

Figure 6-1. The Knowledge Infrastructure Learning Curve.

Figure 6-2.The political dynamic: jumping to conclusions; jumping to solutions.

The Multi-Attribute Tradeoff Analysis approach is designed to consider thousands of scenarios, tracking their relative performance against a broad number of attributes. Using computer models and visual techniques, stakeholders are shown how various approaches succeed or don't succeed in protecting city inhabitants at reasonable cost. These analyses are typically conducted over a number of years in order to explore a variety of alternatives, to adequately inform decision-makers, and to allow researchers to make recommendations on which refined strategies to evaluate next. The process is based on an acknowledgment that diverse stakeholdersindustry, government, and environmental interests, among othershave distinct criteria, but that each can agree on the desirability of the "cheap/clean corner" when the economic and environmental performance of numerous strategies is displayed on scatter plots (Figure 6-3). Used in this fashion, the tradeoff analysis fosters brainstorming, which in turn entrains diverse policy makers in the decision-making process and helps to identify consensus strategies.

Figure 6-3. Generic example of scatterplot showing cost-effectiveness vs. environmental performance of control strategies

To illustrate the tradeoff approach, Mr. Connors showed a data set from an electricity planning exercise conducted from 1988 to 1996 with a large group of New England stakeholders. Using strategies derived from brainstorming sessions with the stakeholder audience, Mr. Connors illustrated cost vs. SO_X emissions for a large number of strategies, over a range of assumptions. He demonstrated how these strategies focus progressively on cheap/clean strategies for each successive variable:

Starting with the cost/SO_X emissions curve, he selected all the strategies that were in the cheap/clean corner, then examined these using the second variable. By continued selection of clean/cheap strategies for a series of variables, a narrower set of robust cheap and clean strategies was identified. Mr. Connors added that, pedagogically, the tradeoff approach was useful in identifying dirty and costly strategies as well. Knowing what not to do is as important as knowing what to do, particularly if the outcome of the decision-making process is subject to many influencing parties.

For the purpose of the "Bringing It All Together" discussion, Mr. Connors suggested that participants think about what pieces of the "knowledge infrastructure learning curve" were in place, and which needed development or strengthening. He spoke of these pieces as "links" in the knowledge chain. Links include data, emissions inventories and models; institutions and people; and outreach to decision makers, the media, and the public at large. As with any "chain," the most important links are those that are missing or weak.

Other specific topics for the discussion part of the session included (1) integration of policies, (2) communication/ knowledge dissemination, (3) stakeholders, and (4) a 6-month plan.

Presentation by Professor Mariano Bauer

Professor Mariano Bauer began his talk with an anecdote about a student taking a biology exam. The student has only studied worms and is presented with a question about elephants. "Well," he says, "let's begin by describing the elephant's tail. It's long and at the end narrows down, like a worm." From there the student goes on to share all he knows about worms. The point is that we tend to discuss what we know, but that problems usually occur in new, less understood terrain.

Prof. Bauer said that the Mexico City Project is aimed not only at educating Mexican decision makers, but also various US sectorsacademic, private and publicas to how pollution problems differ across political and geographic strata. Environmental problems are linked to developmental problems. Prof. Bauer explained that a country can have quick or slow development, but that quick development may allowonce the development has taken placethe time and the money to address environmental issues.

Prof. Bauer discussed available technologies/strategies in terms of "hard" (e.g. new internal combustion vehicles and fuels, improved mass transit) and "soft" (urban planning, demand management, marketing of lifestyle changes). One aspect to be taken into account for an integrated assessment is the "global village" effect. He said that developing countries currently are pursuing lifestyle changes that mimic developed countries, largely spurred on by the media. For instance, the US popularity of minivans is spreading to Mexico, despite concerns regarding fuel economy.

In the U.S., Prof. Bauer stated, more than 80% of all driving goes no further than ten miles from home. Small, high-efficiency cars could achieve significant gains. Prof. Bauer argued that consumer choices were influenced by the information environment, dominated by the mass media. Lifestyles of industrialized societies are emulated elsewhere. He also believes that fashion is more powerful than reasoned argument (for instance, when people spend a great deal more for a name brand when the quality is no different). Prof. Bauer talked about "A question of image"could the auto industry not promote very small but fancy cars?

Prof. Bauer said that something is missing from the "think tank" approach, specifically the need to convey the message using mass media. This needs to go beyond marketing people, as any program conveys many visual messages beyond what the content is about. A 1995 World Energy Congress round table on transport and the environment had representatives of academia, oil and auto industries, and international bodies, but no mass media. He concluded by saying that instead of the media being a barrier, we should try to bring them in as part of the solution.

Discussion Summary

Some participants said more data were needed, others identified problems with existing data. Some said the problem wasn't the data but the decision-making process. Most agreed that an integrated assessment should be a parallel rather than a serial process, and that low-cost, politically feasible alternatives can provide early improvements while other strategies were being explored.

There was wide agreement on the need to better understand health issues, and explore methods to better integrate science and social opinion in formulating policies.

Important links were highlighted, including the link between air pollution and global warming, and developed and developing countries. For the latter, an example was provided of developed countries exporting older (less efficient, more polluting) technologies to developing countries, which then trigger trade sanctions against those countries. Also, cost effectiveness as an evaluation metric was cited as an important link between different fields that don't necessarily communicate in the same language. Evaluating the consequences of policy, including getting feedback from people whom policies affect, was considered important in terms of linking actions to outcomes.

Discussing the need to integrate different problems raised many other questions of how to make necessary linkages. For instance, better mass transit and improved transportation planning are critical to air pollution and also to solving problems of congestion and mobility. Some participants identified the need to give the environmental sector more influence over the transportation, construction, and development sectors. The role of industry, how to promote clean technology, and the potential to redirect investments were raised as considerations.

The role of the media was also cited by a number of people as an important factor in being able to implement effective policies. Similarly, public education was generally agreed to be a necessary element of the project.

There was some discussion about the potential political and educational uses of constructing a scenario of what happens if we do nothing. One suggestion was to oversimplify and provoke. This could be accomplished similarly to what the Dutch did, constructing a future environmental scenario if current trends continue for 25 years. Political tools could also be built around health information, for instance an economic assessment of total health costs of air pollution.

Politics was also discussed with regard to legislation, standard setting, and enforcement. The political environment could perhaps also be changed by employing media skills or networking. We need to make it politically feasible for the legislators and policy makers to do the right thing.

A critical factor is to define an audience for ourselves. How to reach decision makers and build credibility were discussed. There are different policy makers we need to reach and to educate, particularly the Mayor of the city and the Governor of the state of Mexico. But there are also many small actors; local authorities don't have time or capability, and we can help answer questions before they jump to conclusions.

Some people commented on developing the human resources to carry out the work. We need to increase the number of people with air pollution expertise, as well as the general level of knowledge of air pollution. Finally, the desire for more meetings like this one was expressed.