High Levels of Pollutants Found Inside Cars.

The California Air Resources Board (ARB) and the South Coast Air Quality Management District (SCAQMD) have found that exposure to some air pollutants and toxic compounds may be 10 times higher inside vehicles than in ambient air. A two-year, $440,000 study is the first to gather particulate data inside vehicles and to collect real-time information under a range of traffic and driving conditions.

The purpose of the study was to measure motorists' personal exposure to common motor vehicle pollutants in Los Angeles and Sacramento. The study measured direct exposure to gaseous pollutants, diesel soot, and other fine particulates. ARB researchers also began looking at pollutant levels inside school buses. They found that levels of hydrocarbons and carbon monoxide were between two and 10 times higher inside vehicles than at roadside or fixed monitoring stations. Researchers also found similar levels of toxic compounds such as benzene, 1,3-butadiene, ethyl benzene, toluene, xylene, and MTBE, all considered toxic by ARB and the U.S. Environmental Protection Agency. The variations depended on the pollutant, the type of road, and the level of traffic.

As much as one-half of the pollutants inside test cars were emitted by the vehicle ahead. Motorists who used air-conditioning systems and those who drove with their air vents open were exposed to similar amounts of pollution. Researchers learned that people who use carpool lanes were exposed to pollutant levels well below those measured in other traffic lanes, possibly because carpool lanes are less congested and further removed from truck lanes. Dr. Alan Lloyd, ARB chairman, said, "We're learning that peoples' highest daily exposure to air pollutants may be during their commute to and from work. Also, we have concerns about the potential impact on bus riders, especially children."