This story was produced as part of the Colorado Captiol News Alliance. It first appeared at cpr.org.
A nationwide movement to warn consumers about the health risks of cooking with natural gas has hit a speed bump in Colorado.
On Dec. 19, a federal court issued an injunction against the state, blocking it from enforcing a first-in-the-nation law requiring retailers to affix yellow health warning labels on gas stoves.
Colorado lawmakers approved the law in May 2020. It was set to take effect on Aug. 6, but the Association of Home Appliance Manufacturers (AHAM) filed a federal lawsuit a day earlier, claiming the requirement violated the First Amendment by compelling retailers to make controversial claims about their own products.
The state’s attorney general declined to enforce the law until a federal court settled the challenge. With the recent injunction, U.S. District Court Judge S. Kato Crews, appointed by former President Joe Biden, ruled there is, at a minimum, “robust disagreement” about whether gas stoves cause or contribute to health issues. As a result, the appliance manufacturers will “likely succeed” in the arguments behind their claim, Crews wrote.
The court will now consider whether to block the law permanently. While Crews could theoretically reverse himself, the temporary injunction marks a major victory for gas stove defenders, who have spent decades arguing the cooking devices don’t clearly threaten human health. It’s also a setback for air quality advocates and scientists who want the cooking devices treated like cigarettes or other dangerous products.
Here’s a breakdown of the legal battle and why it’s attracting national attention.
How would Colorado’s labelling law work?
Gov. Jared Polis signed the legislation into law last May. If allowed to take effect, it would require retailers to display a yellow warning label on gas cooking devices with a straightforward request: “Understand the air quality implications of having an indoor gas stove.”
An adjacent QR code or link would then direct consumers to a webpage maintained by the Colorado Department of Public Health and Environment. Initially published in August, the page currently notes breathing pollution linked to gas stoves can increase the risk of heart disease, lung conditions and some cancers, with footnotes citing government webpages and peer-reviewed research.
No other state has a gas stove labeling law, but some have considered the idea.
Similar bills have failed to win over lawmakers in Illinois and New York. In California, lawmakers approved a bill requiring stoves to bear labels warning that the devices release “toxic pollution,” but Gov. Gavin Newsom vetoed it. Meanwhile, Massachusetts lawmakers have revived an earlier attempt to affix warning labels onto gas stoves.
What’s the argument behind the lawsuit filed by the Association of Home Appliance Manufacturers?
The trade group represents stovemakers like Samsung and Whirlpool. It filed the federal lawsuit a day before Colorado’s labelling law was set to take effect. Colorado Attorney General Phil Weiser agreed not to implement the requirement until the court resolves the dispute.
At the core of the case is the science behind gas stoves and human health. Under precedent set by a 2018 Supreme Court case, governments cannot force private companies to disclose information about their products unless that information is “purely factual and uncontroversial.”
The appliance manufacturers argue Colorado’s proposed label wouldn’t meet the standard. To make its case, AHAM hired epidemiologist Stacey Benson (at a rate of $425 an hour) to complete a 54-page research review, which concluded current studies do not clearly show gas stoves cause health issues like cancer, heart problems or asthma.
What do scientists say about gas stove risks?
It’s true that scientists aren’t in perfect alignment about the risk presented by gas cooking devices.
The American Lung Association recently updated a literature review on the impact of burning fuels indoors, finding additional evidence that gas stoves harm lung health, while noting that other studies have not found a statistically significant link between the cooking devices and asthma issues.
Rob Jackson, a professor of Earth System Science at the Stanford Doerr School of Sustainability, has spent years researching the indoor air quality impact of gas stoves. He said it is frustrating to see federal courts wait for researchers to confirm that pollutants known to be dangerous outdoors are also dangerous indoors.
“You would never stand over the tailpipe of your car breathing in pollutants like nitrogen dioxide and carbon monoxide and benzene, and yet we stand over a gas stove breathing the same pollutants day after day,” Jackson said.
Jackson’s most recent study, for example, found gas and propane stoves emit significant amounts of nitrogen dioxide, a pollutant linked to a higher risk of asthma, heat and lung diseases. By switching to all-electric cooking, it claims households could reduce nitrogen dioxide exposure by over a quarter, guarding residents against a gas the federal government has regulated outdoors for decades.
It’s also not the first time scientists and public health officials have raised concerns about gas cooking. In 1981, an EPA committee on indoor air pollution concluded that gas stoves could impair lung function in children. More recently, top medical groups — including the American Public Health Association, the American Medical Association and the American Lung Association — have all adopted formal resolutions saying gas stoves create harmful indoor air pollution.
Did the federal judge consider research on gas stoves and indoor air pollution?
Physicians for Social Responsibility intervened in the case to defend Colorado’s labeling law.
The public health advocacy group retained two of its own expert witnesses. One noted research showing gas stoves result in elevated levels of indoor air pollutants. The other expert detailed studies showing those same pollutants are linked to adverse health impacts, such as asthma and heart disease.
Judge S. Kato Crews, however, wasn’t persuaded. In the ruling pausing the labeling law, he concluded claims on Colorado’s gas stove webpage were not only “controversial,” but also “appear to be the minority view at best, and based on outdated information at worst.”
Jackson, the air quality scientist, said that’s not his view of the current research. He recently assisted on another study that estimated nitrogen dioxide exposure based on real-world measurements from more than 100 homes. It found that gas and propane stoves may contribute to up to 19,000 adult deaths annually in the U.S. and account for about 200,000 current cases of pediatric asthma.
Instead of requiring universal scientific consensus, Jackson said the court could apply a “precautionary principle” that’d allow consumers to evaluate scientific evidence and make the best decision for their households.
“We know these gases hurt us. We should do everything we can to reduce exposure,” Jackson said.
What’s next for indoor air quality advocates trying to put warning labels on gas stoves?
Kirsten Schatz, an air quality advocate for the Colorado Public Interest Research Group, said she’s confident the judge will reconsider the decision as the case proceeds.
“Once the interveners in the state can really dig in and demonstrate all of the scientific evidence, it's going to be clear that gas stoves do pose a risk to our health, and that there's no legitimate scientific debate,” Schatz said.
Other public health advocates are less confident that Colorado’s labeling law can survive in its current form. Jamie Long, a senior staff attorney for the Public Health Law Center, said the preliminary injunction indicates the court will “almost certainly" rule in favor of appliance makers.
At the same time, a final ruling could offer a roadmap to lawmakers, outlining alternative approaches that might satisfy the court in the future. Long said a similar pattern has allowed policymakers to craft health warnings on cigarettes. While courts have rejected more aggressive versions of those laws, others have moved forward.
“We've seen this in the tobacco context where sometimes it's one step forward, two steps back,” Long said. “I’d recommend that they keep at it and try to find a path forward.”
