Quality of air getting better; Study finds decreased auto carbon monoxide levels key to progress


Believe it or not, the quality of air in the mid-Atlantic region is getting better, mostly because of reductions in carbon monoxide emissions from automobiles.

A three-year University of Maryland study published in today's issue of Geophysical Research Letters shows carbon monoxide (CO) -- one ingredient in the noxious stew of chemicals known as ozone -- dropping 23 percent over the past 10 years. That suggests other pollutants are dropping as well, said Bruce Doddridge, a research scientist in UM's department of meteorology and one of the authors of the study.

"Carbon monoxide is a tracer of other pollutants that are man-made, and it indicates to us how things are changing," said Doddridge. "It indicates the air quality is, indeed, getting better and that technology is improving to make motor vehicles more efficient."

The amount of carbon monoxide in auto emissions has been cut nearly in half in the Baltimore-Washington area since local governments instituted the Vehicle Emissions Inspection Program (VEIP) in 1981, said Diane Franks, chief of the division of air quality planning at the Maryland Department of the Environment.

The figures dropped 42 percent in the Washington area and 45 percent in Baltimore, she said.

"There's a lot of other sources of carbon monoxide," she said, "but 70 percent of it comes from vehicles, which makes controlling it easy. You know what your target is. Now, if we can get that worked out with the ozone, that'd be great."

Dan Pontious, executive director of Maryland Public Interest Research Group (MaryPIRG), was not as impressed with the findings.

"It shows things are improving for one pollutant, but that's not our biggest problem right now," he said. "This doesn't mean by any means that our air is clean at this point."

Ozone, better known as smog, is a mix of hydrocarbons, carbon monoxide and nitrogen oxide cooked under bright sunshine. It can cause lung damage, eye irritation, breathing difficulties, coughing and chest pains.

While carbon monoxide and hydrocarbons have been reduced, nitrogen oxide, released mainly from coal-burning power plants, has not, said Russell Dickerson, a professor in UM's department of meteorology and another author of the study. "That's the No. 1 problem."

Baltimore Gas and Electric and Potomac Electric Power Co., which supply electricity to the Baltimore and Washington metropolitan areas, have been struggling to meet state regulations to reduce polluting fossil fuel emissions from their coal-burning plants.

BGE is installing equipment at its Brandon Shores Plant on the Patapsco River that is designed to reduce emissions of nitrogen oxide by 65 percent by 2001.

In their study, the UM scientists compared carbon monoxide concentrations at Big Meadows in Shenandoah National Park, Va., from December 1994 through November 1997 with those from 1988 to 1989. Levels decreased from 204 parts per billion to 166 parts per billion.

They chose the Virginia site because "there are no strong local sources of pollution in the park," said Kristen A. Hallock-Waters, a graduate student in chemistry and the lead author.

"Not many people live there, there are no factories or power plants, you can see what's coming into the region."

Figures from street-corner monitors in downtown Baltimore could be skewed, depending on whether the traffic light is red or green.

The results of the UM test mirrored U.S. Environmental Protection Agency figures that show a decrease of 18.3 percent in man-made carbon monoxide emissions during the same period.

"It's gratifying to see the emissions estimates agree with what's been observed in the real world," said Dickerson. "Cars are supposed to be cleaner, and this shows that they are."

Reducing the amount of carbon monoxide in the air helps to reduce ozone. In fact, ozone levels have dropped in the past decade, said Bill Ryan, ozone forecaster at UM.

Eleven Code Red days were reported this summer, in which ozone levels reached at least 125 parts per billion, compared with 14 days in 1997, one of the worst ozone seasons in recent history.

"We can say there's been an improvement over the last decade in ozone. It's been slow, but there's been an improvement," said Ryan.

Pub Date: 9/15/99

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