The changing natural world at our doorsteps | Illustration and text by Patterson Clark
July 19, 2011
With DAN KEATING THE WASHINGTON POST
Washington’s improving air quality
When summer's heat roasts the Washington area, air quality tends to worsen but compared with a decade ago, it has improved.
"We still get bad days," says Timothy Canty, an atmospheric scientist at the University of Maryland, "but it's getting better." A 2002 EPA regulation required states to reduce emissions of nitrogen oxides (NOx). On hot, stagnant days, NOx and volatile organic compounds (VOCs) produce ozone (O3).
"Ozone is a good thing at high altitudes, where it blocks damaging ultraviolet rays," says Canty, "but at ground level, ozone inflames the lungs." It causes acute respiratory problems, reduces lung capacity and impairs the body's immune system. "In some cases," says Canty, "high ozone levels can lead to death." Ozone can also damage vegetation, including crops, and it will degrade rubber and plastic.
Alerting the public to air-quality dangers, the Metropolitan Washington Council of Governments (MWCG) issues a daily air-quality forecast, which gauges the presence of ozone and aerosols, airborne particles resulting from combustion, especially from industry and vehicles.
SOURCES: Environmental Protection Agency, District Department of the Environment, Metropolitan Washington Council of Governments, Clean Air Partners