Second Air Advisory Issued; Air Quality Unhealthy Yesterday

DES MOINES-Air quality is predicted to reach unhealthy conditions today across much of north central and northwestern Iowa, southern Minnesota and portions of eastern Iowa due to particulate air pollution, state officials said today. Air quality yesterday was also unhealthy across much of the state, measuring 101 to 153 on the national Air Quality Index.

"People with heart and lung disease, asthmatics, older adults and children should reduce prolonged or heavy extended outdoor activity and wait for better air quality to return," said Brian Button, DNR air information specialist. "People shouldn't fear being outside, but sensitive groups should limit outdoor, aerobic type activities."

"It isn't a healthy day to be running, cycling or other intensive outdoor activities," said Button. "Those activities can increase the chances of respiratory problems for sensitive groups," he said.

A pocket of air over portions of the Upper Midwest has had elevated particulate levels for three days due to a thermal inversion that is holding emissions close to the ground.

Levels yesterday were highest in Scott County measuring 153 on the AQI. Clinton and Polk Counties measured 112 and 106 and a monitor in Mason City measured 111, Linn County 108 and Palo Alto County at 101. Surrounding counties likely had similar levels. Air quality in southern Iowa measured moderate air quality. Levels were also high Tuesday.

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 in the nation are purple for very unhealthy (201 to 300) and maroon for hazardous (301 to 500.) Air quality in Iowa rates good to moderate on the vast majority of days, with several days of unhealthy air monitored annually.

Particulate matter is a generic term to describe microscopic sized solids and aerosols in the air. Because the particles are so small they are able to penetrate the deepest parts of the lungs, increasing the likelihood of symptoms in sensitive individuals, including children, the elderly and those with heart and respiratory disease.

Thermal inversions may be contributing to the unhealthy air. Inversions occur when cold air is held to the ground by a warm air layer above that acts as a lid, trapping particulate and gas emissions from tailpipes, burning and industries. Hazy skies are often associated with higher particulate levels, which scatter light in the atmosphere. Airborne emissions can also react to form particulate pollution as well.

Iowans can view current particulate pollution levels online at www.epa.gov/airnow. Online data also includes ozone smog levels in the summer months as well.

For more information contact Brian Button at 515-281-7832 or by email at brian.button@dnr.iowa.gov.