Vehicle exhaust is biggest pollutant

How vehicles compare to the Lowcountry's largest industrial polluters

Wayne Barfield moved to the outer edge of Summerville to get away from the city. But every workday, the respiratory therapist finds himself breathing some of the worst-polluted air in the Lowcountry while he sits in rush-hour traffic.

Charleston, Berkeley and Dorchester counties are on the verge of violating federal Clean Air Act standards for ozone, the greenhouse gas emitted by carbon fuel engines. If they violate the standard, vehicles could be forced to undergo emission inspections and road-building could be restricted.

The reason is simple: The fumes faced by commuters such as Barfield and people who live near busy roads are considered the most immediate air pollution threat to human health because they are emitted — and they tend to collect — right there where you breathe.

With "ground-level ozone" about to spike in the summertime, the S.C. Department of Health and Environmental Control is adding the three counties to its list of areas where ozone forecasts will be issued as a health warning.

Ground-level ozone is caused largely by sunlight reacting with pollutants from cars and trucks.

A newly established EPA standard for ozone — 75 parts per billion — must be met by 2010. A recent Charleston County reading was 74 parts per billion, and nearby counties could be included in restrictions if a county fails to meet the new standard.

Seven counties, mostly in the Upstate, already are at or over 75 parts per billion.

Just how much pollution vehicles cause isn't specifically tracked by health agencies. An estimate compiled by The Post and Courier suggests it might be more than people realize. More than a half-million vehicles are registered in the three counties in question; on an average day, about 140,000 vehicles travel the congested Interstate 26 stretch alone.

Looked at as a single emission source, the half-million vehicles would rank as one of the biggest polluters in the Lowcountry.

Toxic spew

A half-million vehicles emit more than 3 million tons per year of five air pollutants that one researcher listed among the most significant threats to human health. That figure is a rough estimate, compiled by The Post and Courier using the number of vehicles registered with the S.C. Department of Motor Vehicles and a calculation supplied by researchers at the John Muir Institute of the Environment at the University of California, Davis. The numbers would not include commercial, trucking or tourist vehicles from out of the area.

The tonnage includes four times more deadly carbon monoxide than is emitted by the heaviest industrial discharger in the Charleston area, 1,000 more tons of nitrogen dioxide and more carbon dioxide than all but two factories.

It's not nearly the total load dumped by industries in the area that the state Department of Health and Environmental Control tracks for air emissions. But exhaust pollutants are spewed out along the ground where people breathe, "where they are fresh and the most toxic," according to the federal Clean Air Task Force, a nonprofit organized by university-based scientists to study environmental issues.

"The most susceptible (and overlooked) population in the United States subject to serious health effects from air pollution may be those who live very near major regional transportation routes, especially highways," concluded a 2007 Tufts University School of Medicine study of the health effect of vehicle pollutants on people who live near highways.

The fumes cause breathing problems. They can damage the lungs, heart and nervous system or cause birth defects. And they can cause cancer.

Among other research:

--A National Academy of Sciences panel found links between short-term exposure to smog and premature death.

--A preliminary study at Cedars-Sinai Medical Center in Los Angeles suggests breathing polluted air might trigger brain tumors.

--An EPA study indicated 78 percent of the total added cancer risk in outdoor air comes from diesel engine exhaust, according to an analysis by Environmental Defense.

Carbon monoxide, nitrogen oxides, sulfur dioxides, volatile organic compounds, along with particulates and mercury, rank as the biggest threats to health in air pollution, according to Greg Huey, a professor of atmospheric chemistry at Georgia Tech. Gasoline cars, as well as diesel trucks, emit all of them.

"It's scary. When you're sitting there you're thinking, 'whoa.' It's eye-opening," said Barfield, the commuter.

What can you do?

Don't spend time near roads or don't breathe — that's about it for avoiding vehicle exhaust pollutants. In a mobile society, the fumes are collateral damage. But there are a few safety tips that can help.

The first is, take care of yourself. Research at the National Jewish Medical and Research Center on the effects of ground level air pollution on children with asthma suggests that the pollutants do the most damage to patients who are already in poor control of the disease, said Nathan Rabinovitch, associate professor of pediatrics.

"The bottom line is, you need to be concerned first of all about everything else that is going to make you sick," he said.

Most of the others tips are common sense and easier said than done, such as avoiding traffic congestion.

Except there's one surprising suggestion: Keep a car window cracked open, especially when you are stuck in traffic, said Matthew Keegan, in "4 Vehicle Exhaust System Safety Tips." It will keep carbon monoxide from building up in the car.