Fine particulate matter pollution in Iowa exceeded national air quality standards at 34 locations during 2009, including six instances in Muscatine, five in Davenport and five in Clinton.
The National Ambient Air Quality Standard (NAAQS) for PM 2.5 (particulate matter 2.5 micograms or less) is a 24-hour average of no more than 35.4 micrograms per cubic meter. The NAAQS represents the U.S. Environmental Protection Agency's best estimate of the threshold for adverse health effects.
The 34 exceedances statewide for PM 2.5 compares to 25 instances in 2008 and 44 in 2007.