NW Iowa Particulate Air Pollution Levels Unhealthy Thursday

DES MOINES—Air quality reached unhealthy levels for sensitive groups Thursday in northwest Iowa due to particulate air pollution, according the DNR.

Under the national Air Quality Index (AQI), recent air conditions fell slightly into the orange classification or “unhealthy for sensitive groups,” where prolonged, heavy exertion outdoors could increase the likelihood of symptoms in sensitive individuals such as persons with respiratory and heart disease, the elderly and children.

Iowans may have noticed recent hazy skies and decreased visibility, characteristic of the light scattering nature of the microscopic airborne particles.

The higher the color-coded AQI, the poorer the air quality. An AQI of 1 to 50 is green or good, 51 to 100 is yellow or moderate, 101 and higher is orange or unhealthy for sensitive groups, 151 and higher is red or unhealthy for everyone, 201 and higher is very unhealthy and 301 and higher is hazardous.

The AQI of 102 was measured at a monitor located in Palo Alto county. Adjacent counties also likely experienced the same conditions, due to the regional nature of this pollutant. A monitor located in Estherville also measures particulate matter, but in a manner requiring detailed filter analysis.

Those results will not be available for several weeks, but can yield clues to the types of chemicals and gases that form the particulate pollution. Airborne sulfates or nitrates are likely, but air officials won’t know for sure until the filters undergo analyses at multiple laboratories across the nation. This type of pollution is often regional in nature, caused by emissions that travel and react over great distances.

The state also experienced several days of particulate pollution in March over larger areas.

What is Particulate Matter?

Particulate matter is a generic term for small bits of solid materials, liquid droplets, or aerosols in the outdoor air. Fine particles less than 2.5 microns--about the size of a human red blood cell--pose the greatest health risks and are regulated pollutants. Some can be seen only with an electron microscope.

Particulates originate from many sources such as direct emissions of smoke, or form from airborne reactions of sulfur and nitrogen oxide gases depending on the air chemistry, time of year, and weather.