DETROIT (AP) -- The U.S. Environmental Protection Agency says the entire state of Michigan now meets the eight-hour outdoor air quality standard for ozone.
Ground-level ozone is known as smog and is formed when pollutants interact on warm, sunny days. Motor vehicles, factories and other sources release the chemicals that contribute to ozone, which can cause breathing problems.
The EPA said in a release Monday it granted Michigan's request to reclassify the air quality for Allegan County.
The agency says outdoor air monitoring data from the counties for 2007-2009, and preliminary data from 2010, meet the federal standard. It also approved Michigan's plan to continue to meet the standard through 2021.