Chicago is the only large metropolitan area in the United States to consistently violate the new standards U.S. EPA proposed yesterday for smog-forming nitrogen oxides.
The standard, which would not come into effect until 2021, would limit the air pollutant to 100 parts per billion, measured every hour. Nitrogen oxides emitted from car and truck tailpipes and power plants are a key ingredient in smog.
Chicago averaged nitrogen oxide rates of 116 parts per billion between 2006 and 2008, according to EPA. (The next highest urban area was San Diego, at 87 parts per billion.) However, Chicago's poor rating could be due to the location of the city's monitor, sitting atop a heavily trafficked interchange between the Eisenhower and Kennedy expressways.
"It's very congested there, with a steady stream of cars and trucks," said Laurel Kroack, chief of the Illinois EPA's air bureau. "It's very difficult for us to do anything about that."
Federal mandates for cleaner car and truck engines should help reduce the nitrogen oxide pollution, which many environmental groups groused as being too lenient. A stricter level -- say 50 parts per billion -- would have required tougher local pollution controls, they say.
"We are disappointed that given a range of options EPA proposed last year ... the agency chose the least protective health standard," said Brian Urbaszewski, director of environmental health at the Respiratory Health Association of Metropolitan Chicago (Michael Hawthorne, Chicago Tribune, Jan. 25). -- PV