Gas and propane stoves create NO2 when they heat the air so much that two atoms of oxygen combine with one atom of nitrogen. Electric stoves, which don’t get as hot, do not cause the same reaction. NO2 inflames the airways,

“Whether you have a gas stove, or electric stove, there's very, very high justification and need for indoor settings, kitchens in particular, to have improved ventilation,” he says. “To me that has to be addressed simultaneously.”

A study finds that the nitrogen dioxide emitted from stoves impacts the entire home, in some cases hours after the stove was turned off.