FRIDAY, May 3, 2024 (HealthDay News) -- People in homes with gas or propane stoves regularly breathe in unhealthy levels of nitrogen dioxide, a new study says.

Typical use of these stoves increases exposure to nitrogen dioxide (NO2) by an estimated 4 parts per billion, averaged over a year, researchers report.

That’s three-quarters of the way to the NO2 exposure level deemed unsafe in outdoor air by the World Health Organization, researchers noted.

“That’s excluding all outdoor sources combined, so it makes it much more likely you’re going to exceed the limit,” lead researcher Yannai Kashtan, a doctoral student in Earth system science at Stanford University, said in a news release.

Breathing high levels of NO2 over time can intensify asthma attacks, and has been linked to decreased lung development in children, researchers noted.

The mix of pollutants coming from gas and propane stoves could be responsible for as many as 200,000 current cases of childhood asthma, with one-quarter attributed to nitrogen dioxide alone, researchers estimated.

Long-term exposure to NO2 from gas stoves also is high enough to cause as many as 19,000 deaths each year, researchers added.

For the study, researchers used sensors to measure concentrations of NO2 throughout more than 100 homes of various sizes, layouts and ventilation methods.

“I didn’t expect to see pollutant concentrations breach health benchmarks in bedrooms within an hour of gas stove use, and stay there for hours after the stove is turned off,” senior researcher Rob Jackson said in a news release. He's a professor with the Stanford University Doerr School of Sustainability.

People who live in homes smaller than 800 square feet — roughly the size of a small two-bedroom apartment — are exposed to twice as much NO2 over the course of a year compared to the national average, researchers found.

They also are exposed to four times more NO2 than people living in the largest homes studied, upwards of 3,000 square feet.

Because home size makes such a difference, exposure differs among racial, ethnic and income groups, researchers added.

Long-term NO2 exposure is 60% higher among American Indian and Alaska Native homes, and 20% higher among Black and Hispanic households, researchers said.

“People in poorer communities can’t always afford to change their appliances, or perhaps they rent and can’t replace appliances because they don’t own them,” Jackson said. “People in smaller homes are also breathing more pollution for the same stove use.”

The study also found that cooking food emits little to no nitrogen dioxide.

“It’s the fuel, not the food,” Jackson said. “Electric stoves emit no nitrogen dioxide or benzene. If you own a gas or propane stove, you need to reduce pollutant exposures using ventilation.”

In larger homes, NO2 concentrations routinely spiked to unhealthy levels even if a range hood was on and venting air outdoors, researchers said.

“We found that just how much gas you burn in your stove is by far the biggest factor affecting how much you’re exposed. And then, after that, do you have an effective range hood – and do you use it?” Kashtan said.

The new study was published in the journal Science Advances.

More information

The American Lung Association has more on nitrogen dioxide.

SOURCE: Stanford University, news release, May 3, 2024