The number of bad air days caused by ground-level ozone in the Washington area declined by more than 40 percent since 2003, according to a recent estimate.
The region’s air quality is monitored by the Metropolitan Washington Air Quality Committee.
Joan Rohlfs, MWAQC’s Clean Air Quality Planner attributed the decline to stronger controls on the region’s power plants, a federal plan for cleaner cars and a decrease in pollution blown from power plants to the West.
Local environmental groups wondered whether cooler weather was responsible for the improvement, according to The Washington Post.
“It used to be that for every day there was a 90 degree day, there would be ozone exceedance. Now we have half the number of ozone exceedance days for 90 degree days,” Rohlfs said.
The MWAQC is a committee within the Metropolitan Washington Council of Governments, an organization which brings together local area governments on issues that cross jurisdiction lines.
The organization has created a color-based index to let people know how safe the air is.
This summer, the region experienced 19 Code Orange, Code Red or Code Purple days, days on which the level of ozone exceeds standards set by the Environmental Protection Agency.
The index advises that “healthy people should limit strenuous outdoor work or exercise” and “refuel cars after dark” on Code Red days. On these days, certain public buses in the Baltimore-Washington area are free.
The MWAQC is under pressure by the EPA to reduce ozone levels further.
The Air Quality Committee is trying to get the region in line with EPA standards,” said Jeanne Saddler, Public Affairs Director for MWAQC.
The EPA’s standards, set by the Clean Air Act, limit the concentration of six basic pollutants. The Washington area is in compliance with all but two criteria: ground-level ozone and particulate matter.
If the region does not comply by a 2009 deadline, the government could decrease its federal transportation funding, Saddler said.
The beltway is safe for now because the dangerous ozone season lasts from May until September. Ozone forms best under extreme heat and a lot of sunlight. Automobiles, power plants and other sources release nitrogen oxide and volatile organic compounds, which, in the presence of sunlight and heat, form ground-level ozone.
Ozone exacerbates respiratory problems. For example, it can irritate the respiratory system and thereby lower resistance to colds and pneumonia, according to the MWAQC’s web site.
Particulate matter poses a more dangerous health threat—small particles can enter the lungs or bloodstream and potentially cause serious health problems.
