Idle Hands

The women belong to a nonprofit group called the Asthma Free School Zone, which, for the past year, has been holding covert stakeouts of schools around the city to aid a campaign against vehicle idling. New York City prohibits idling for spurts of longer than three minutes (the fine is from three hundred and fifty to two thousand dollars), though the law is rarely enforced. In 2004, after receiving a tip from the A.F.S.Z., Eliot Spitzer, who was the attorney general at the time, sued several school-bus companies for breaking the rule, and last month, as governor, Spitzer signed a ban on all bus idling in school zones. "In Switzerland you have to turn your engine off if you're more than four cars behind the stoplight," Rebecca Kalin, the group's founder, said the other day. "Idling is rude there. It's like burping-you just don't do it."

Kalin had arrived at P.S. 274 a little before two o'clock, with three colleagues: Lori Bukiewicz, a public-health worker; Jen Richmond-Bryant, an assistant professor at Hunter College (courses: Ventilation, Indoor and Outdoor Air Quality); and Bin-Yun Zheng, the group's assistant. When no one was looking, they wheeled out a small gray cabinet with a plastic tube sticking out of the top. The cabinet emitted a low buzzing noise, and it contained a car battery, two Sidepaks-used to gauge air quality by counting small particles called PM2.5-and an instrument called an Aethelometer, which measures black carbon.

…In an hour and a half, there had been twelve idlers: seven cars, one truck, and four school buses. The PM2.5 reading was on the high side.