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.

Like atmospheric methane and carbon dioxide, ground-level ozone is on the rise. But ozone, a noxious chemical byproduct of fossil fuel combustion, has received relatively little attention as a potential threat to corn agriculture.