Air Quality Advisory Lifted

February 3, 2005

For more information, contact Brian Button with the Department of Natural Resources at 515-281-7832.

DES MOINES-An air quality advisory was allowed to expire today at 11 am, as air quality improved across western and central Iowa. Morning pollution levels remained elevated at monitors in Linn, Scott, Clinton and Van Buren counties due to an overnight thermal inversion, but air quality is improving as the day progresses.

Yesterday, particulate pollution levels across large areas of Iowa and the Upper Midwest was elevated with Air Quality Index readings in the 90s across much of the state and 111 in Polk County. An AQI of 101and higher is considered unhealthy for sensitive groups.

On Tuesday, the Air Quality Index measured 119 in Linn County, 113 in Polk County, 108 in Clinton County, 107 in Scott County and 104 in Palo Alto County. Surrounding areas experienced similar levels. Other areas of Iowa experienced elevated, but moderate pollution levels. Widespread areas of the Upper Midwest, Great Lakes and Ohio Valley experienced similar conditions.

Particulate matter is a generic term to describe microscopic sized soots and aerosols that can penetrate the deepest parts of the lungs, posing increased likelihood of symptoms in sensitive individuals, including children, the elderly and those with heart and lung disease when engaged in prolonged outdoor activities such as exercise.

Particles are directly released when coal, gasoline, diesel fuels and wood are burned. Particles also form from chemical reactions of nitrogen oxides, sulfur oxides, organic compounds and ammonia.

Hazy skies are often associated with higher particulate levels, which scatter light in the atmosphere. Particulate pollution can form year-round, unlike summertime ozone smog, which requires hot, sunny conditions.

The Air Quality Index (AQI) reports pollution levels using a color-coded and numerical range for pollutants. The higher the AQI, the poorer the air quality. An AQI of 1 to 50 is green or good, 51 to 100 is yellow or moderate, 101 to 150 is orange or unhealthy for sensitive groups, 151 to 200 is red, unhealthy for everyone. Rarely monitored are purple for very unhealthy (201 to 300) and maroon for hazardous (301 to 500.)

Iowa’s air quality still meets federal health standards, but an increase in the number or severity of days with unhealthy air could pose clean up efforts. Iowa typically has several days of unhealthy air annually.