DES MOINES, Iowa - The air quality index (AQI) sits in the moderate category as a hot weekend is set to begin in Iowa.
High humidity, hot temperatures and low air movement often translate to a lower AQI value.
"When you get hot and humid conditions like this in the summer and there's not a lot of air movement, what we tend to see is that the particulates released into the air by various pollutants, traffic and so forth, don't mix out very well," said National Weather Service Meteorologist Jim Lee.
Friday's moderate AQI means the air quality is acceptable, but there may be a moderate health concern for a small number of people unusually sensitive to air pollution.
Lee tells WHO Radio News daytime high temperatures will be well over 90 degrees beginning today and continuing through the weekend.
The heat index will get close to 100 degrees, or more, through Monday.