The first portion of a groundbreaking study of Iowa’s air is nearly complete. The Iowa Department of Natural Resources has tracked emissions from the state’s 300 largest businesses for several years. D-N-R Air Quality Specialist Brian Button says this new study surveys some 600 small and medium sized businesses.Button says the D-N-R is also gathering information on emissions that don’t come from businesses, such as emissions from paint or gas stations.The business surveys are due at the D-N-R’s Air Quality Bureau by May 15th. Button, says the information will ultimately give the state a gauge of the types and quantities of materials being released into the air. He says the state can then examine the impact of those materials and develop air quality strategies. Button says many businesses have already turned in their reports, but he expects a flood of surveys to hit the D-N-R office just ahead of the Tuesday deadline.