Debate on pulmonary safety of gas stoves: Is the risk just hot air?
FROM ATS 2024
SAN DIEGO — While there is currently no smoking gun definitively showing that indoor nitrogen dioxide (NO2) concentrations from gas appliances are a cause of pulmonary diseases, the circumstantial evidence of the baleful effects of gas stoves on lung function is pretty compelling, said participants in a pro-con debate.
The debate was held at the American Thoracic Society’s international conference.
PRO: Gas stoves cause lung disease
Arguing for the “pro” side, John R. Balmes, MD of the University of California, San Francisco, and a physician member of the California Air Resources Board, began by admitting that “I would never have said gas stoves cause lung disease, but that’s what they assigned me.”
Gamely proceeding anyway, Dr. Balmes noted that natural gas — methane — is a potent greenhouse gas, and that cooking with natural gas leads to generation of NO2 with high peak concentrations in the home, especially in the kitchen, but in other rooms as well.
“We know that NO2 is an irritant gas that can cause bronchoconstriction, airway hyperresponsiveness and inflammation, and there’s increased risk of asthma and COPD exacerbations,” he said.
The US Environmental Protection Agency (EPA) outdoor ambient air standard for NO2 is 100 parts per billion (ppb) or lower, which are the levels needed to prevent asthma exacerbations. In separate meta-analyses there was a 1.05 rise in asthma incidence per every 2 ppb of NO2, and an increase of 1.07 in COPD incidence for every 5 ppb of NO2, Dr. Balmes noted.
The respiratory effects of gas stoves were revealed in a 2013 meta-analysis of 10 studies from North America and Europe, which showed a pooled odds ratio for current asthma of 1.34. Building on these data, authors of a 2022 paper estimated that 13% of childhood asthma could be prevented by elimination gas cooking.
Although the causative link is missing, the evidence is abundant that natural gas isn’t good for anyone, he acknowledged.
Con: More evidence needed
Arguing for the “con” side of the question, Meredith C. McCormack, MD, MHS, professor of medicine in the pulmonary and critical care division at Johns Hopkins University in Baltimore, said that “more definitive evidence is needed to define whether gas stoves cause lung disease.”
But Dr. McCormack didn’t let the natural gas industry off the hook, noting that a systematic review and meta-analysis of cooking with gas in high-, middle-, and low-income countries showed that domestic use of gas fuels vs. electric was associated with increased risk of asthma (1.11 overall), COPD (1.15), and pneumonia (1.26).
The link between gas and risk of asthma was significant only for adults, however, and the data on the risks for COPD and for pneumonia or other respiratory infections came almost exclusively from low-income countries, she noted.
Despite the lack of evidence for a causative link, however, Dr. McCormack pointed to evidence that indoor NO2 is an air pollutant that acts as a respiratory irritant, and that indoor NO2 levels in homes with gas stoves have been shown to be more than twice as high as those in homes with electric stoves.
Other evidence shows that indoor NO2 is associated with increased symptoms and use of rescue medications for children with asthma, and with shortness of breath, nocturnal symptoms, reduction in lung function, and exacerbations in COPD.
Still other studies have shown that exchanging a gas stove for an electric stove can reduce NO2 concentrations in the home by up to 50%, but there is still a need for clinical trial evidence of a health benefit for such an exchange, she said.
And even if a gas stove is swapped out for an electric or induction range, household members with asthma are exposed to other hazards, including second-hand smoke, cooking exhaust, candle or incense burning, outdoor particulate matter that finds its way indoors, mold, and mouse or cockroach allergens, she noted.
