"It's been the hottest summer on record in many cities on the East Coast. And with that blistering weather has come a lot of days of unhealthy air.
On Wednesday, at least 75 areas from San Francisco to Portland, Maine, are warning their residents about high air pollution.
In the Washington, D.C., metropolitan area, local officials sent out more air pollution warnings this year than they had since 2002 — three Code Red, 26 Code Orange and more predicted on the way."
Elizabeth Shogren reports for NPR's Morning Edition September 1, 2010.