Marnie Stein, Acting Air Quality Bureau Chief, says the report, for 2020, shows emissions of sulfur dioxide dropped more than 90 per cent since 2002. And nitrogen dioxide emissions have fallen 70 per cent.
"The largest source of pollutants back in 2002 was electricity generating facilities and manufacturing facilities that burned coal. A lot of those have either shutdown, converted to natural gas, or are relying on renewable energy now."
The annual report tracking six major air pollutants, is based on numbers provided by the 300 largest emission sources such as ADM, 3M, Cargill, and food and ethanol producers. Smaller businesses are required to report every three years.
"For the larger facilities, we look at ones that have a big change from the previous year, either up or down in emissions. And then we select a certain number every year to do a complete, comprehensive review of."
Iowa began collecting data from large sources in 1992, and from smaller sources in 2000.
Additional information on air quality in Iowa and across the country is available from the US EPA, Iowa DNR, and American Lung Association.