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 $5 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.