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Tuesday, May 2, 2023

The Truth About Gas Stoves

Carefully weigh the risks versus the benefits


“The world of tomorrow is cooking with gas!” This phrase was popularized by the gas industry as far back as the 1930s, promoting gas stoves as clean and reliable.

Carmen Miranda even sang, “Cooking With Gas” in the 1948 film “A Date With Judy” and the American Gas Association (AGA) got Bob Hope to adopt the catchphrase “Now you’re cooking with gas” in his routines. 

The gas industry’s marketing campaign was a big success: gas came to be seen as clean and natural, and eventually gas stoves became the cooktop of choice for most professional chefs.

Today, about 40 million U.S. households use gas stoves—more than 30 percent of homes; in New Jersey, California, Chicago, and New York City, it’s about 70 percent of households. But recently, concerns have arisen  about their impacts on children’s health. What does the science show, and why are we only hearing about this now?

In January, the chair of the Consumer Product Safety Commission (CPSC) announced that emissions from gas stoves could be hazardous and that it was looking into ways to reduce the indoor air pollution they produce. Although the CPSC said it was not considering a ban on gas stoves, the media was suddenly awash with reports on the dangers of gas stoves and campaigns that defended them.

What are the health risks of gas stoves?

The natural gas that fuels gas stoves is primarily methane which, when burned, turns into carbon dioxide. Burning the fuel also produces nitrogen dioxide (NO2), which can aggravate respiratory diseases such as asthma, and result in coughing or difficulty breathing. How much NO2 and other pollutants people are exposed to depends on the size of their cooking space and the ventilation available.

In 1971, the EPA established regulations to limit outdoor exposure to NO2 to 53 parts per billion (ppb) over the course of a year. In 2010, the agency determined that, in fact, exposure should not exceed 100ppb in one hour. 

The EPA has never set any regulations for indoor NO2 air pollution. Canada and the World Health Organization, however, have set indoor NO2 guidelines for one hour at 90ppb and 106ppb respectively.

recent study involving researchers at Columbia University’s Climate School and the Mailman School of Public Health found that NO2 concentration when cooking with gas stoves reached an average of 197 ppb; when gas stoves were replaced with electric stoves in 20 households, daily NO2 concentrations fell by 35 percent .

2020 study  by Rocky Mountain Institute, Physicians for Social Responsibility, Mothers Out Front, and Sierra Club found that boiling water might produce 184 ppb of NO2; baking a cake in a gas oven could produce 230 parts per billion, and roasting meat could produce 296 ppb. 

Using bigger or more burners or turning flames up higher can result in even more NO2 being emitted. In other words, gas stoves can produce concentrations of NO2 that easily exceed EPA’s outdoor NO2 air quality standards if adequate ventilation is not used.

Because children’s respiratory and immune systems are not fully mature, and because they have faster breathing and physical activity rates, high indoor levels of NO2 can impact children’s health. They can result in increased susceptibility to lung infections and asthma, respiratory problems, learning deficits, and cardiovascular issues, and can exacerbate allergies. 

1992 analysis found that NO2 levels comparable to the amount a gas stove releases increases the risk for a childhood respiratory illness by 20 percent. A more recent study found that 12.7 percent of U.S. childhood asthma cases, or one in eight, were attributable to gas stove use, confirming the findings of earlier studies.

“[The 12.7 percent finding] is really complex in terms of the actual causal pathway,” said Harry Kennard, senior research associate at Columbia University’s Center on Global Energy Policy “That’s not to say that the combustion byproducts of gas are healthy — they aren’t. But the way that they impact you is really a sort of complex assembly of lots of different things—the building morphology, socio-demographic factors, and the availability of decent ventilation.”

Ventilation can lessen risks but won’t completely eliminate them. Gas stoves, unlike gas hot water heaters and dryers, are not uniformly required to be vented to the outside. Proper ventilation—exhaust hoods, fans over stoves, or open windows—can reduce air pollutants, but in many places, vents cannot or are not required to connect to the outdoors. 

Exhaust hoods that filter and recirculate the air indoors are less effective at cleaning the air. Moreover, a National Health and Nutrition Examination Survey found that only 21.1 percent of gas stoves in homes with children were consistently used with the stove’s exhaust vent.

Compared to cooking with an electric stove, cooking with gas also produces twice as much harmful particulate matter, which can have health impacts on the heart and lungs. Gas stoves can also release formaldehyde, a human carcinogen, and carbon monoxide, which is odorless and can be toxic in high concentrations. Carbon monoxide levels have been found to be three to six times higher in homes with gas stoves.

A gas stove also pollutes when it is off. A 2022 study found that gas stoves, even when not in use, can leak as much benzene, a carcinogen, as secondhand cigarette smoke. Another study  that analyzed natural gas samples found that 95 percent of them contained benzene, for which there is no safe level. That study also found 21 hazardous air pollutants in unburned gas, including hexane and toluene, which can affect the nervous system, liver, and kidneys.

Stanford University researchers measured emissions for 53 stoves while on and off. Seventy-six percent of unburned methane leaked out through pipes and fittings when stoves were off. High levels of methane can reduce the amount of oxygen in the air, which can have a variety of health impacts. 

Methane is also a greenhouse gas 80 times more potent than carbon dioxide over 20 years. The study calculated that the 2.6 million tons of methane emissions leaked from U.S. gas stoves in one year are equivalent to the carbon dioxide produced by about 500,000 cars.

Because the quality and size of housing can determine exposure to indoor air pollution, the problem is usually worse for low-income communities. Low-income residents who have smaller homes or apartments with inadequate ventilation and perhaps many occupants will be more susceptible to the risks of gas stove pollution. 

And due to inadequate heating, low-income residents may use gas stoves to heat their homes which will produce elevated levels of nitrogen dioxide and other hazardous pollutants.

In addition, research shows that low-income communities have more incidences of asthma, which can be aggravated by gas stove use. Because switching to electric cooking may not be affordable for many low-income residents, one solution is for governments to provide credits or rebates to help with the purchase of plug-in induction stovetops or electric stoves.

The gas industry’s response

In the face of the mounting criticism of gas stoves, the gas industry has used the fact that the EPA and the Consumer Product Safety Commission have not regulated gas stoves as evidence that they are safe. 

One gas utility executive said, “The science around the safe use of natural gas for cooking is clear: there are no documented risks to respiratory health from natural gas stoves from the regulatory and advisory agencies and organizations responsible for protecting residential consumer health and safety.”

Meanwhile, the gas industry has mounted an anti-electrification campaign, sending robotexts to residents about how their electric bills would soar if they switched to electric stoves. 

The American Gas Association has blogged that “All electric homes require expensive retrofits.” And since 2018, the AGA and American Public Gas Association have paid young social media and Instagram influencers to sing the praises of cooking with gas.

More recently, an AGA spokesman said that emissions from cooking itself, and not the stove, are the main problem. And in response to the latest study that found gas stoves increased childhood asthma cases by 12.7 percent, the AGA claimed the study was not substantiated by “sound science” because the authors didn’t test real appliances, citing another study that found no association between cooking with gas and asthma in children.

Who knew what when?

But in fact, the gas industry itself has been studying the risks from gas stove pollution since the early 1970s. A draft report by the AGA shows that it already had concerns about indoor air pollution in 1972.

Scientists have also known that the emissions from gas stoves can harm human respiratory systems for decades. In 1975, the EPA published a study that showed exposure to nitrogen dioxide from gas stoves caused respiratory problems. 

A 1981 EPA report on indoor air pollutants and their adverse health effects said, “Unvented gas cooking is probably responsible for a large portion of nitrogen dioxide exposures in our population. 

In many homes, chronic exposures to nitrogen dioxide indoors may exceed established national ambient-air quality standards.” And in 1983, Congressional hearings on indoor air quality concluded that unvented gas stoves could produce nitrogen dioxide and other pollutants that could irritate respiratory systems. 

In 1986, the EPA asked the Consumer Product Safety Commission to assess the risks of indoor sources of nitrogen dioxide, saying more epidemiological research was needed, but not until 2011 and 2013 did the CPSC warn the public that exposure to nitrogen dioxide could be harmful.

The gas industry continued to dispute the science and hired its own researchers to conduct studies; it argued that regulations were unnecessary because people could take actions on their own to ventilate. It has spent millions lobbying Congress to protect its interests. In the end, no regulations on gas stoves or their emissions were ever passed.

Gas stoves become cultural pawns

Now as the Consumer Product Safety Commission studies and seeks public comment about the gas stove issue, the U.S. Oil and Gas Association has sponsored a new nonprofit called Hands Off My Stove whose mission is to “preserve our right to choose to cook our meals any way we want without government interference.”

House Republicans introduced the “Guarding America’s Stoves (GAS) Act” and the “Stop Trying to Obsessively Vilify Energy (STOVE) Act” to prevent the CPSC and other agencies from banning gas stoves. 

In response to the Department of Energy’s proposed new energy efficiency standards for gas stoves that could result in some existing ones being removed from market, the “Save Our Gas Stoves Act” would prevent the Department of Energy from setting energy efficiency standards for gas stoves. 

Republican senators also introduced the “Natural Gas Appliances Standards Act of 2023,” which would prevent the Department of Energy from making rules that could prohibit the sale of any natural gas appliance. And Florida Republican Governor Ron DeSantis has proposed the elimination of sales tax on gas stoves to encourage their use.

Gas stoves have become pawns in the political culture war because they are the gateways to natural gas fueled heating and hot water. About half of all U.S. homes use natural gas for heat and hot water. 

Achieving President Biden’s goal of net zero by 2050 will require switching these homes to electricity. Twenty-two states plus Washington D.C. and Puerto Rico have already made commitments to clean electricity by 2050 or sooner.

Dozens of U.S. cities have also instituted or are considering banning natural gas in new construction; however, a federal appeals court just overturned the ban on natural gas in new construction in Berkeley, California, the first U.S. city to establish a ban. To counter the gas ban trend, 20 states with Republican-controlled legislatures have adopted “preemption laws” to prohibit their cities from banning natural gas.

In contrast to California and Washington, which banned gas in new construction through building codes, New York could soon become the first state to ban gas appliances through legislation. 

Governor Hochul’s bill would ban gas and other fossil fuel use for appliances in new construction of single-family homes or buildings with three stories or less beginning at the end of 2025; at the end of 2028, gas would be banned in new commercial buildings or structures with four stories or more. 

There would be exemptions for restaurants, laundromats, hospitals, backup generators, and manufacturing facilities. Hochul’s proposal is dependent on passing the state budget, which is already late.

What if you have a gas stove?

Anyone who spends a lot of time cooking on a gas stove is at greater risk from its pollutants. Children, pregnant women, and those with respiratory problems are especially vulnerable.

The best way to avoid indoor air pollution in the kitchen is to switch to an electric or induction stove. Electric stoves cook food without a flame and can have coils that sit on the cooktop, or heating elements beneath a glass surface. They are healthier and safer than gas stoves, and have outperformed gas stoves in many Consumer Reports tests.

Induction cooktops are a type of electric cooktop, but they produce energy through an electromagnetic field beneath a glass surface. The heat is actually created within magnetic cookware: stainless steel, iron, or induction-compatible cookware.

Induction stoves are safer than gas stoves because they produce fewer indoor air pollutants, the glass surface never gets hot, they cook faster, are easy to clean, and are three times more energy efficient. 

The drawbacks are that induction stoves can be twice as costly as gas stoves, the electricity in your kitchen may need to be upgraded and rewired, your electric bills could go up, and you may need to purchase new pots and pans.

While President Biden does not support a ban on gas stoves, he is encouraging electrification through his Inflation Reduction Act, which provides a tax credit for up to $840 for a new electric or induction cooktop, or electric wall oven. It also provides up to $500 toward the costs of rewiring.

If you cannot switch to electric, there are other measures you can take to protect your health.

  • If you cannot afford an induction stove, consider purchasing a portable induction burner which doesn’t require additional wiring.
  • Install a ventilation hood over the cooktop, ideally vented to the outdoors, and use it whenever cooking.
  • Use an air purifier with high-efficiency particulate air (HEPA) and carbon filters. Most will not remove toxic gases but will lessen particulate matter; some special air purifiers can filter out volatile organic compounds.
  • Open windows when you cook and use a fan in the window to circulate the air.
  • Use back burners instead of front ones; use fewer burners and cook at lower heat.
  • Avoid long cooking times on the stove or in the oven.
  • Use electric appliances when possible: microwaves, toaster ovens, kettles, slow cookers, pressure cookers, or rice cookers.

“Ventilation is absolutely key,” said Kennard, adding that it’s unfortunately not getting enough attention in the gas stove discussion. 

“We saw this through COVID. It took a long time for people to understand that alongside masks and vaccines, actually ventilating rooms was one of the most effective ways of preventing the transmission of the disease.  That same principle applies to providing clean fresh air to whatever space you’re cooking in—it is central.”