Air quality in the National Capital Region shows improvement, based on an analysis completed by the Metropolitan Washington Air Quality Committee (MWAQC). According to the mid-course review analysis, the air quality trends indicate that the region is likely to meet the Environmental Protection Agency’s (EPA) one-hour ozone standard by 2005.

Over the past 10 years, the number of days that ozone levels exceeded EPA air quality standards declined—even on hot, dry summer days when ozone most often forms. In addition, air quality monitors throughout the region have measured lower concentrations of ozone and more monitors are in compliance with EPA’s one-hour standard. Since 1990, the geographic scope of air pollution violations has reduced in size by about 75%.

“We can really see the cumulative affect of all of the initiatives that state and local governments have undertaken over the past 15 years,” said MWAQC Chair Tom Dernoga.

The region has made great strides in reducing the emissions that cause ozone. For example, nitrogen oxides—found in vehicle exhaust and power plant emissions—have decreased by approximately 39% between 1990 and 2004, despite a population growth of 58%. During this time, volatile organic compounds—such as fumes from chemical solvents, paints and gas cans—were reduced by more than 65%. Further reductions are anticipated in 2005.

"These results are welcome news and evidence that our control strategies are taking hold and moving us toward cleaner air," said Maryland Department of the Environment Secretary Kendl P. Philbrick. "As we look ahead to even greater success in this effort, we must not forget that air quality is an issue of great importance that goes beyond the interests of a single region. It requires that every state understand and take responsibility for actions that affect people beyond its borders. We need better pollution controls on power plants outside this region." While local emission reductions have reduced ozone pollution, the region’s air quality continues to be significantly affected by ozone and emissions transported from areas outside of the metropolitan Washington area. States upwind of the region began controlling their nitrogen oxide emissions as a result of state initiatives. Together with local emission controls, emission reductions from upwind states are expected to improve the air quality in the metropolitan Washington for meeting the one-hour ozone standard in 2005.

The Washington region, originally designated as a “serious” nonattainment area for violations of the one-hour ozone health standard, was reclassified as “severe” nonattainment for failing to meet the 1999 attainment deadline. Although the region’s 1-hour ozone deadline is 2005, the EPA’s new 8-hour ozone standard requires the Washington region to meet tougher requirements by 2010.

For more information on COG’s air program, please visit https://www.mwcog.org/environment/planning-areas/air-quality/