E-Mail IMAGE: Maize experimental field plot fumigated with elevated ozone (green pipes). Maize leaf samples were collected from similar rings throughout the growing season, to understand the response in diverse maize lines. view more Credit: Ainsworth lab Although stratospheric ozone protects us by filtering out the sun's ultraviolet radiation, tropospheric ozone is a harmful pollutant. A new study has shown that ozone in the lower layers of the atmosphere decreases crop yields in maize and changes the types of chemicals that are found inside the leaves. Ozone is formed when nitrous oxide, released from industries and tail pipes of cars, is broken down by sunlight and chemically reacts to form ozone. Researchers at the University of Illinois Urbana-Champaign have been studying the effects of ozone pollution on crops for over 20 years at a unique facility where crops can be grown under real-world farm field conditions but with increased concentrations of ozone pollution.