16 July 2004

Citizen volunteers in Mexico City air quality studies

Some 18 million people live in and around Mexico City, one of the world's most polluted cities. Once known for its azure skies, pollution generated by motorists, power plants and industry is trapped by mountains around the city.

These conditions allow very high levels of ozone to be generated when brownish layers of nitrogen oxide are illuminated by ultraviolet-A and blue wavelengths of sunlight. There can also be very high concentrations of particulate matter suspended in the air.

The good news is that Mexico City experienced a rare spate of clear skies this spring. The bad news is that the pollution returned in earnest during June.

To learn more about the effects on human health of severe air pollution, environmental health professionals have planned a new study involving 32 elderly volunteers. According to an Associated Press story by Will Weissert, each volunteer will wear a vest equipped with air sampling devices for 24 hours every other day.

The volunteers, who are from areas near air quality monitoring sites, will keep a log of their daily activities. The air sampled by the vests will be compared with the air quality measured by fixed instruments. The health of the volunteers will also be tracked.

Mexican authorities hope to expand this project to other cities and to also employ younger volunteers. This volunteer science project could produce important new information for health and air quality specialists. It's the latest of many projects in which citizens have volunteered to help collect scientific data.

For details about air quality monitoring in Mexico City, see www.sima.com.mx/sima/df/dfeng.html.

For views of the Popocatepetl Volcano from Mexico City on clear and polluted days, see www.sima.com.mx/sima/df/volcang.html.

Forrest M. Mims III