The nine metropolitan areas requiring tighter regulation are: Atlanta, Georgia; Baltimore, Maryland; Chicago, Illinois; Hartford, Connecticut; Houston, Texas; Milwaukee, Wisconsin; New York City; Philadelphia, Pennsylvania and Washington DC.

The EPA reviewed air quality plans for 10 areas in total, and found that nine need further improvements. Only Springfield in western Massachusetts was found to have adequate smog reduction plans.

“Each of the plans we reviewed shows a strong commitment to reducing harmful air pollutants that cause smog,” EPA Administrator Carol M. Browner said. “We are confident that, working with states and cities, we can finalise flexible, common-sense approaches to reducing pollution and bring cleaner, healthier air to breathe for millions of Americans within the next decade.”

Under the Clean Air Act Amendments of 1990, Congress required the 10 areas to develop air pollution reduction plans by this year.

With the exception of western Massachusetts, each of the areas will need to update their transportation and air quality planning to ensure that public health and the environment are protected to the level required under the Clean Air Act.

The announcement is also reflected in a consent decree being lodged today with the U.S. District Court in the District of Columbia.

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