Chicago is the only U.S. metro area that would fail to meet a tougher standard for smog-forming nitrogen oxides proposed Monday by the Obama administration.
The more stringent limit is intended to help protect people who suffer from asthma and other respiratory ailments. But Illinois officials contend they won't be able to do much about it without cleaner cars and diesel trucks, two major sources that are regulated by the federal government, not the states.
U.S. Environmental Protection Agency should have imposed an even tougher limit on nitrogen oxides, based on the latest science about health risks posed by breathing the noxious pollution. States would have more than a decade to comply with the limit.
Setting a different standard, closer to the lower end of a range recommended by the EPA's scientific advisers, would have affected dozens of other cities plagued by dirty air, including Los Angeles, San Diego, New York, Phoenix and Denver.
Nitrogen oxides from tailpipes, factories and coal-fired power plants are key ingredients in lung-damaging smog, which is a chronic problem in Chicago and other urban areas on hot, sunny days. The EPA's new standard of 100 parts per billion, measured every hour, is intended to reduce short-term exposures that can trigger asthma attacks.
Chicago averaged 116 parts per billion between 2006 and 2008, according to the EPA. The next highest urban area was San Diego at 87 parts per billion, followed by Los Angeles at 84 parts per billion.
"We're moving into the clean, sustainable economy of the 21st century, defined by expanded innovation, stronger pollution standards and healthier communities," said EPA Administrator Lisa Jackson, announcing the latest in a series of regulatory changes that reflect growing understanding about the health threats posed by dirty air.
By most measures, Chicago typically has some of the nation's dirtiest air. But the region generally is considered slightly cleaner than other major metropolitan areas.
Laurel Kroack, chief of the Illinois EPA's air bureau, attributed the Chicago area's high level of nitrogen oxides to the location of the city's nitrogen oxide monitor: atop a Loop office building near the traffic-clogged interchange between the Eisenhower and Kennedy expressways.
"It's very congested there, with a steady stream of cars and trucks," Kroack said. "It's very difficult for us to do anything about that."
Other federal rules requiring cleaner engines and fuels will help. Yet when the EPA imposed tougher standards on diesel engine manufacturers during the Bush administration, it rejected pleas from Illinois and other states to require tune-ups for older engines when brought in for routine maintenance.
Diesel engines can stay on the roads for years. Some can be adjusted to reduce emissions, but trucking groups complained that imposing a broad mandate would increase fuel costs.
Environmental groups had urged the EPA to set the short-term nitrogen oxides exposure limit at 50 parts per billion. Doing so would have required tougher air pollution controls in most of the nation's urban areas.
"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.
Urbaszewski and other activists are pushing for other solutions, including enforcement of a state law and a Chicago ordinance that limit idling by diesel buses, trucks and delivery vans. They also want the federal government to require tighter restrictions on coal-fired power plants, another major source of nitrogen oxides.
As part of the rule announced Monday by the U.S. EPA, the agency will expand its monitoring network to ensure at least one monitor is located next to a major highway in urban areas of more than 500,000 people. The monitors will be in place by 2013, and states will have until 2021 to comply with the new standard.