Gas stoves are contributing more to global warming than previously thought because of constant tiny methane leaks while they’re off, a new study found.

The same study that tested emissions around stoves in homes raised new concerns about indoor air quality and health because of levels of nitrogen oxides measured.

Even when they are not running, U.S. gas stoves are putting out an amount of methane equivalent to 2.4 million tonnes of carbon dioxide each year, a team of California researchers found in a study published in Thursday’s journal Environmental Science & Technology. That’s equivalent to the annual amount of greenhouse gases from 500,000