Large areas along the ridges of the North Carolina mountains have become dead zones in recent years partly because of pollution, says plant pathology professor Dr. Bob Bruck. Along with other factors, such as ozone levels and insect infestation, pollution has tipped the balance of the fragile ecosystem, most visibly affecting the large trees. Bruck has studied changes to the mountain ecosystem over the past two decades and was among the first scientists to suggest acid precipitation—polluted rain, fog, and snow–was killing spruce and fir forests along higher elevations of the Appalachian Mountains. “These areas are vacuum cleaners for pollution,” he says. “They soak up all the sulfuric and nitric acids produced by power plants and cars.”

Data Bruck collected on stunted trees, acidic soils, and the loss of native plant species in test plots on Mount Mitchell, along with research presented by others, helped convince Congress to pass the Clean Air Act of 1990. But he says the legislation hasn’t solved the problem, partly because it doesn’t regulate all vehicle emissions. Bruck continues to monitor the test plots annually and says the impact of pollution and acid rain is moving steadily down the mountains. “We’ve taken a rare and beautiful ecosystem and severely abused it,” he says. “We must stop the domino effect at lower elevations.”

Dr. Chris Frey is trying to do just that by studying vehicle emissions. A civil engineering professor, he is learning more about emission rates to lower exposure risks for people and help improve air quality statewide. Using a portable monitor with a tailpipe probe similar to those North Carolina service stations have used for years to test vehicles for annual state inspections, Frey analyzes emissions as he drives around town and on the highway.

Periods of acceleration far and away produce the greatest amount of pollution, Frey says, and account for about half of emissions on a trip in which most time is spent idling or cruising at a steady speed. “People think that sitting in traffic jams is the major cause of urban air pollution,” he says. “But what’s really bad is when those drivers step on the gas and start moving again.” Because of Frey’s research, the U.S. Environmental Protection Agency is developing a new vehicle emission model, which could lead to tougher air-quality standards for passenger vehicles.

State and local agencies struggling with the haze of ozone and other pollutants over North Carolina metro areas also can tap Frey’s data to develop appropriate measures for limiting emissions. The NC Department of Transportation, for example, has tweaked the timing of traffic signals at some intersections to reduce stop-and-go commutes and the resulting emissions spike. “Non-attainment of national air quality standards can affect industrial growth and federal funding of highway projects,” Frey says. “Providing realistic information about the relationship between vehicle dynamics and emissions is
crucial to effectively preventing emissions.”

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