REGULARLY CITED AS ONE OF THE WORLD’S CITIES WITH THE worst air pollution, Mexico City has become an environmental conundrum. But a new international initiative that includes U of T’s Heather MacLean just might be the answer to cleaning up the thick, brown smog over the Mexican megacity.

MacLean, assistant professor of civil engineering, is working with EMBARQ, a partnership between the World Resources Institute (WRI) in Washington, D.C., and the Shell Foundation. The group is setting out to advance sustainable development around the world by focusing on transportation problems in cities in developing nations.

MacLean’s involvement in the Mexico City project is supported by the Environmental Technology Advancement Directorate of Environment Canada and the WRI. A large, diverse team from Mexican government agencies, the World Bank, the WRI and academia has been assigned to the project, and for good reason – MacLean says Mexico City’s air pollution problem includes a wide variety of unique challenges.

“We are concentrating on one overarching theme – transportation – but there are many aspects to cover, from political, social, engineering, scientific, climatic and economic perspectives.”

The problem is based on a number of interrelated factors:

• A physical location in a valley surrounded by mountains that causes pollution from
  vehicle exhaust to become trapped over the city
  
• A population of 18 million, many of whom are poor and dependent on public transport
  
• Old and poorly-maintained automobiles, buses and trucks
  
• A subway system with a decreasing ridership, due to overcrowding
  on some lines and safety and security issues
  
• Good, new publicly-operated buses that face strong competition from smaller, higher-polluting buses that are run by private operators more cheaply
  
• An army of old, high-polluting taxis

With these odds, is there any hope of easing air pollution in Mexico City? MacLean points to one key reason for optimism – political will. “The governments in Mexico City and surrounding areas want to fix this problem. That is the most essential first step. There are many cities in developing nations that do not have political will. Without it, no amount of expertise can help.”

MacLean will work on the project over the next four years, focusing on alternative bus technologies, cleaner fuels and rapid transit systems. “We will investigate high-speed, designated busways that would attract more people and cut down on the number of high-polluting cars and private buses. We also might try hybrid electric buses that have worked well in other cities.”

She emphasizes, however, that there are a number of areas to consider. “We have to look at this situation from environmental, economic and social perspectives. For example, if it costs too much to keep hybrid buses in service, maybe it doesn’t matter how good their fuel economy is. Transport is a fascinating issue because it involves all of society and how personal choices must meet with environmental needs and economic realities. Our goal is to find a balance between all of these factors.” — Paul Fraumeni