Older Cars Fouling Region's Air Quality

Agency Study Links Recession, Pollution

The recession is contributing to higher levels of air pollution in the Washington area as new car sales plummet and older, dirtier vehicles remain on the road longer, according to a recent study by regional planners.

The trend is expected to show up across the country as transportation planners use vehicle registration data collected after the economy soured to adjust local air quality forecasts required by federal law. The Metropolitan Washington Council of Governments is believed to be the first planning agency to analyze that data.

Vehicles on the road in the Washington area are an average of six months older than they were in 2005. The increase, from about 7.9 to 8.4 years, is enough to push the region perilously close to violating its limits for traffic-related pollutants, according to the study.

"If you trade in a 1995 Jeep Cherokee for a new one, that's a big difference in emissions," said Ronald F. Kirby, COG's transportation planning director. "We can't keep emissions going down unless we get newer vehicles in the fleet."

Last month, President Obama signed "cash for clunkers" legislation that will provide as much as $4,500 to people who trade in older, less fuel-efficient vehicles to buy or lease ones that get better gas mileage. The measure, which some critics said does not do enough to cut carbon emissions, is intended to help the auto industry while putting cleaner cars and trucks on the road.

In the Washington area, tailpipe emissions next year will be as much as 7.5 percent higher than projected in forecasts conducted last year, according to COG's analysis. The increase in vehicle age overwhelmed changes friendly to the environment, such as an increase in hybrid vehicles and a move away from gas-guzzling sport-utility vehicles toward smaller and relatively fuel-efficient passenger cars, the study found.

Kirby said he was particularly troubled that aging vehicles are predicted to cause increased emissions even as motorists are expected to cut their driving by 2.5 percent, in part because of higher unemployment. The finding is at odds with a basic tenet of transportation planning, that tailpipe emissions drop when people drive less.

Rich Denbow, director of technical programs for the Association of Metropolitan Planning Organizations, said the COG study is the first in the country to document the connection between older vehicles and worsening air pollution. However, Denbow said, he expects other areas will find the same problem when they update their air quality forecasts.

"We're the first ones to see it, but I think it will be a national issue," said Denbow, whose organization is based in the District. "Our economy is better than a lot of others, so the [older vehicle] problem isn't as bad here as it will be in other areas."

Michael Replogle, transportation director for the Environmental Defense Fund, said he is concerned that the problem is even worse than COG projected. The computer models that Kirby's staff used have been found to project less pollution than a newer model that planning agencies will begin using in the near future, he said.

Transportation planners said they hope new car sales will rebound as the economy does, but Replogle said he thinks the nation's vehicle fleet will remain on the older side because so much shopping in recent years was fueled by cheap credit.

This is a critical time, transportation planners said, because tighter limits on tailpipe emissions took effect in 2004 and 2007. Having an average vehicle age of more than eight years means that many of those on the road are higher-polluting.