Congestion & Air Pollution

The Washington Metropolitan Area missed a 1999 Clean Air Act deadline for meeting federal health standards for ozone, a key component of smog. The Metropolitan Washington Council of Governments estimates how much air pollution comes from vehicle tailpipe exhausts in the region.  According to Clean Air Act requirements and deadlines these estimates could jeopardize billions of dollars in new roads, transit projects and building permits across the region.  Analysts note that Washington area residents are driving higher-emissions sport-utility vehicles (SUVs) and light trucks in much larger numbers than anticipated. The region's sprawl into outer suburbs is also causing vehicles of all types to be driven farther.

A federal court recently rejected EPA's attempt to extend the 1999 clean air  deadline to 2005 without reclassifying the area to "severe."  Since the court ruled in July, EPA has not taken action to require stronger clean air measures in the region and has indicated that it may delay requirements for such measures until 2004. Although metro DC's unhealthful air has violated federal ozone standards every year since the implementation of the Clean Air Act (passed in 1970), the region still does not have an EPA-approved plan to stop the violations. The Clean Air Act (amended in 1990) required adoption of such a plan in 1994. Technically, no new road or transit projects can receive federal funding until these emissions are curbed, requiring a series of pollution-fighting measures that regional planners say will cost approximately $40 million. Of course, these requirements are always postponed or revised by officials.

Under current standards, the Washington Metropolitan Area had 12 code red ozone nonattainment days (very unhealthy air) in 2002. When measured against a new, more protective ozone standard adopted in 1997, but not yet  implemented by EPA, the Washington area has violated that standard on 34 days in 2002.  AAEA has a very simple smog nonattainment standard: if you can see the air, it is unhealthy to breathe.  According to our standard, we probably had 60 nonattainment days this summer. Summer smog in the DC area sends almost 3,000 people to the emergency room and causes about 150,000 asthma attacks.

Predicting pollution trends through a series of complex computerized calculations are controversial and politically sensitive. Officials may have to plan to put projects on hold until they fund millions of dollars in incentives to  get people out of their cars. To predict pollution levels, the COG analysts include in their calculations census figures, household surveys, vehicle registration data, growth plans and maps. They devise computer models for traffic and use models created by the U.S. Environmental Protection Agency to gauge future vehicle exhaust.  Analysts then try to predict how residents in the region will live and travel.  The calculations focus on forecasts of how much and where population and jobs will grow; and the need for additional roads, transit systems or other changes planned for the region.

First, the computer model divides the District and 17 jurisdictions in Northern Virginia and suburban Maryland into 2,000 zones. [The nonattainment area includes the District of Columbia, Calvert, Charles, Frederick, Montgomery, and Prince George's counties in Maryland; and Alexandria, Arlington, Fairfax, Falls Church, Loudoun, Manassas, Manassas Park, Prince William, and Stafford counties in Virginia]. It then calculates how much traffic in each zone will be created and attracted, based on existing and planned development.  For example, a zone will attract a certain number of trips to its shopping centers or office buildings and create others when its residents commute to work and run errands from home.  The computer model then predicts how many people travel to which places and how often, and whether they drive alone, carpool or take a bus or Metro.  It takes into account that expensive parking downtown will encourage people to take Metro to work. Finally, the computer model predicts which routes drivers will take, assuming that people will take the most direct route and find a way around traffic jams when they form.

The model's limitations lie in predicting lifestyle and economic changes.  It has trouble predicting gas prices and economic swings, both major influences on how much people drive. In the 1960s, the computer calculations failed to anticipate the dramatically higher numbers of women who entered the workforce. They also missed the fact that family members would have to make more trips to do errands, with more of that traffic during weekends.  The model also didn't pick up on the rise of the soccer mom -- or the volleyball dad.