Air quality alert issued for Eastern Iowa

The Iowa Department of Natural Resources issued an air pollution advisory today for Eastern Iowa.

People with respiratory or heart disease, the elderly and children should limit prolonged outdoor exertion until air quality conditions improve, the DNR warned.

Elevated fine particle levels are expected to persist until late Friday morning.

The Environmental Protection Agency's 24-hour health threshold for fine particles is 35 micrograms per cubic meter.

As of noon today, fine particle levels averaged in the high 30s to low 40s across parts of east central Iowa. Monitors recorded fine particulate levels at 45 in Cedar Rapids, 50 in Iowa City, 50 in Muscatine and 49 in Waterloo.

Fine particles are emitted by vehicle traffic and other combustion sources, and are formed by chemical reactions in the atmosphere. Stagnant air masses confine fine particles and pollutant levels rise.

The fine particle levels in the state have been following a pattern of rising rapidly during the evening and nighttime hours, and falling back to levels below the standard in late morning or early afternoon.

The cycle is expected to continue until winds pick up Friday afternoon.

EPA's national air quality map is available at: www.airnow.gov

For Linn County, see:

www.linncleanair.org