Commuting: a breath of traffic's air.

Even if a car's windows are closed, volatile organic chemicals (VOCs) emitted by traffic enter the passenger cabin and build to concentrations that generally match those in roadway air, a new study finds. Moreover, if malfunctions in a car's carburetor allow unburned gasoline to infiltrate the interior, it may pay to open the windows.

Nicolas J. Lawryk and Clifford P. Weisel of the Environmental and Occupational Health Sciences Institute in Piscataway, N.J., sampled gaseous pollutants over a year in two cars during 113 commutes through suburban New Jersey and 33 trips from New Jersey to Manhattan (via the 12-lane New Jersey Turnpike and Lincoln Tunnel). As smaller studies had suggested, drivers confront the greatest exposure to VOCs when traveling in heavy traffic or through pollution-trapping tunnels.

Major differences between the cars occurred only when one, which had a carburetor, developed fuel system malfunctions, Lawryk and Weisel report in the March Environmental Science & Technology.

Until that car was repaired, some unburned volatile substances in gasoline leaked into the cabin. With the windows closed, concentrations of benzene (one of gasoline's carcinogenic constituents) climbed as high as 45.2 micrograms per cubic meter of air-25 times that in the fuel-injected car making the same commute.

Though cars with carburetors are on the wane, Weisel worries that when the millions still on the road develop choke problems or fuel leaks, they could jeopardize health-especially of taxi drivers and others who drive much of the day.

Concerned about just these issues and populations, the California Air Resources Board in Sacramento is planning its own analysis of air quality in cars. It plans to monitor not only VOCs but also a driver's exposure to potentially health-threatening fine dust (SN: 7/1/95, p. 5), notes Peggy Jenkins, who heads the agency's indoor air program.

While not wishing to downplay the health risks posed by auto pollution, Lance Wallace of the Environmental Protection Agency in Reston, Va., points out that even those exceptional concentrations of benzene seen occasionally in this study were no higher than what typically developed inside all motor vehicles 15 to 20 years ago.

For him, the message is that certain automotive problems can erase recent air quality improvements won through better controls on tailpipe emissions and the reformulation of gasoline.