Air Quality Index (Iowa DNR graphic)

It’s not fog but smoke making the air hazy in parts of central Iowa this morning — and you can smell the smoke from the Canadian wildfires.

The Iowa Department of Natural Resources says the Air Quality Index for the Des Moines metro is “unhealthy,” and it’s considered “unhealthy for sensitive groups” across a wide section of central and south-central Iowa.

Meteorologist Andrew Ansorge, at the National Weather Service, explains what’s happening.

“It has less to do with the pressure and more so that we just had a clear night last night,” Ansorge says. “It allows for what we call good radiational cooling, basically, the earth cools off and that allows for temperatures from the surface up to maybe a few thousand feet in the atmosphere to go colder, so that creates a stable atmosphere and doesn’t allow for mixing.”

As the day progresses, warmer weather is anticipated, with highs mostly in the 80s, and he says that should allow the smoke to dissipate.

“That’s going to allow the surface to start warming up and we’ll start what we call boundary layer mixing, basically, the lowest levels of atmosphere we where we live will start mixing,” Ansorge says. “That will help to mix out anything that’s at the ground level. That can be fog, that could be pollutants, that could be in this case, the smoke in the Des Moines metro.”

For now, health officials say Iowans with certain conditions that may restrict breathing, including asthma, should avoid being outside today, and any strenuous activities.

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