Q. I notice in the last month or so that our "Air Quality" rating has fallen in the moderate range several times. Is this the result of the California fires or the Pittsburgh steel mills? -- Bob, Davenport
A. Catharine Fitzsimmons, bureau chief, Air Quality Bureau, Iowa Department of Natural Resources, said, "Thank you for your questions about the Air Quality Index values reaching the moderate range recently. During winter months when the temperature is hovering in the 20 to 40 degree Fahrenheit range we will often see the atmospheric formation of ammonium nitrate fine particulate in the Midwest region. Snow, low winds, atmospheric stagnation and inversions, and moderate winter temperatures are common to these events."
She provided a link to additional information on the subject. To view the information visit qctimes.com/askthetimes
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She also recommended contacting Dr. Sean Fitzsimmons, lead for the Ambient Monitoring group, with the Iowa Department of Natural Resources.
Fitzsimmons said, "Probably not. The emissions from the Pittsburgh steel mills are too small and too far away to have an effect on Iowa air quality. By comparison, the California fires have much larger emissions, but it takes just the right meteorology to transport the smoke to Iowa and to mix the elevated smoke layer down to ground level. Often the California wildfires are driven by high (Santa Ana) winds that blow from the mountains out to sea. These winds inundate coastal areas with smoke before the plume travels out over the Pacific Ocean. This was the case with the devastating Camp Fire that burned in Northern California from November 8 to November 28.
"Historically in Iowa, we have seen elevated fine particulate levels in cold months due to nitrate formation under stagnant meteorological conditions."