Particle air pollution elevated aboard Seattle school buses – Updated

Air on Seattle school buses contains considerably more harmful airborne particles than the surrounding outside air, researchers at the University of Washington report.

In the study, the researchers measured levels of small particles that can penetrate deep into the lungs where they can release harmful chemicals and have been linked to respiratory diseases and other health problems.

These particles, which measure less 2.5 micrometers in diameter, are produced from a variety of sources, including gasoline and diesel engines.

For comparison, a human hair is 70-times wider than largest of these 2.5 micrometer particles, which are called PM_2.5.

In the study, the UW researchers compared particle levels measured by monitors on Beacon Hill and in Kent that are used to measure Seattle’s general air quality with levels on the roadway and with levels within the buses themselves.

The researchers took measurements on buses that service the Seattle School District and the Tahoma School District in the suburbs southeast of the city.

The researchers found that the average concentrations of the particles aboard the buses were two-times higher than the air over the roadway and four-times higher for the city in general. 

The results of the study will be used as part of larger ongoing study to assess what effect air pollution has on children’s health and how best to reduce those risks.

Sara Dubowsky Adar, assistant professor of epidemiology at the UW School of Public Health and Community Medicine and the lead author on the study said that although the levels her team measured on the buses were less than the 24-hour limits set by the U.S. Environmental Protection Agency, short-term exposure to diesel exhaust over a long period may have subtle impacts on children’s lungs.

” We don’t yet know yet how these subtle changes translate to more visible changes in health like worsening asthma symptoms, increased sick days, or decreased lung function but we hope to learn more about these possible impacts as this research progresses,” she said in an e-mail.

The age and design of the buses seemed to play a role in how much higher the particle levels were on the buses compared to the levels on the buses, with newer buses equipped with diesel oxidative catalysts having lower levels.

The researchers conclude that “school buses contribute substantially to children’s daily exposure to air pollution.”

The paper appears in the journal Atmospheric Environment (2008;42:7590-7599). 

This story originally ran Nov. 10. This version has additional quotes from the study author.

To learn more:

• To learn more about Seattle’s air quality visit the Puget Sound Clean Air Agency’s website.
• To see what today’s air is like in various parts of Seattle area go to the Puget Sound Clean Air Agency’s Air Quality Index web site.
• To learn more about PM2.5 and how to protect yourself from the harmful effects of air pollution go to the U.S. National Library of Medicine’s information page on air pollution.
• Read the article in the journal Atmospheric Environment (fee or subscriptions may be required).

Tags: Air Pollution, Asthma, Lung Disease, School Children

Category: Child & Youth Health, Lungs & Breathing, Poisoning & Environmental Health