(Radio Iowa) – Smoke from the Canadian wildfires is being swept out of the state. John Gering of the Iowa Department of Natural Resources has looked at the latest map. “It does appear to be a north to south clearing,” he says. This latest round of smoke had settled at the surface level. That’s why alerts indicated air quality has been unhealthy for sensitive groups. “If it stays up high in the atmosphere, it’s not going to affect people and it’s not going to register on our monitors,” Gering says, “so it’s that combination of emissions, horizontal winds and vertical mixing.” The Iowa D-N-R’s STATEWIDE air quality alert ends at noon today (Monday). The alert has recommended that people reduce long or intense outdoor activities due to the fine particulates in the air.

“They’re about 30 times smaller than the diameter of a human hair,” Gering says, “so they get in your lungs and your lungs have a hard time expelling the small particles.” The fires carry chemicals which in the presence of sunlight form ozone, an odorless gas. Over the past five years, there have been an average of three to four air quality warnings related to high ozone concentrations in Iowa at ground level. By June 12th, there had been 124 — so that does not include this weekend’s conditions.

“Likewise we’ve had 22 exceedences of the fine particulate matter standard reported through July 12,” Gering says, “and there’s going to be some additional exceedences of that standard coming in, rolling in over the next few weeks.” Staff collect filters at monitors throughout the state and take them to the University of Iowa where they are manually weighed. Gering says that process takes a while, so the in-depth analysis of this weekend’s air quality won’t be completed for a couple of weeks.