Chicago's hot new PCB.

Decades after U.S. production of polychlorinated biphenyls ended, a van-mounted device sampling air pollution outside Chicago schools turned up PCB-11. Previously linked to yellow-paint production, this PCB had never been seen tainting air. Keri Hornbuckle of the University of Iowa in Iowa City and colleagues report that PCB-11 tainted 90 percent of the city's air samples, and there were notable hot spots. Overall, this pollutant--perhaps released by old paint--proved Chicago's sixth most abundant airborne PCB.