Air Quality Over Iowa Begins to Improve

Pollutant levels near U.S. Environmental Protection Agency (EPA) health standards for fine particles were present over most of Northern and Central Iowa Thursday, but fell Friday morning.

The EPA’s 24-hour health standard for fine particles is 35 micrograms per cubic meter. On Thursday, fine particle concentrations averaged 46 micrograms per cubic meter in Davenport, 45 micrograms per cubic meter in Clinton, 40 micrograms per cubic meter in Emmetsburg and 34 micrograms per cubic meter in Des Moines. Monitors in the Southern part of the State recorded lower values; 25 micrograms per cubic meter at Lake Sugema and 26 micrograms per cubic meter at Viking Lake.

From midnight to noon on Friday, all monitors across the State averaged less than 35 micrograms per cubic meter. Emmetsburg recorded the highest average concentration of 27 micrograms per cubic meter and Des Moines had the lowest average at 12 micrograms per cubic meter. Davenport averaged 20 micrograms per cubic meter.

Air quality in Iowa is expected to continue to improve as a winter storm enters the State on Saturday.

Fine particles are emitted by vehicle traffic and other combustion sources and also formed by chemical reactions in the atmosphere. Stagnant air masses do not allow the fine particles to disperse, and pollutant levels rise. In the winter, fog droplets at near freezing temperatures capture ammonia and nitric acid and give rise to fine particles of made of ammonium nitrate.

EPA’s national air quality map is available online at www.airnow.gov.

For more information contact Sean Fitzsimmons at Sean.Fitzsimmons@dnr.iowa.gov or at (515) 281-8923.