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,

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

"If you own a gas or propane stove, you need to reduce pollutant exposures using ventilation," one researcher said.

Stanford University research shows how gas cooking can expose people to unsafe nitrogen dioxide levels throughout a home.