The heated debate on gas stoves that became a political issue in the US.
- jonathan levy
- The Conversation*
Cooks love their gadgets, from countertop slow cookers to instant-read thermometers. Currently, there is a growing interest in magnetic induction cooktops: surfaces that cook much faster than conventional ones, without lighting a flame or heating an electric coil.
Magnetic induction has long been popular in Europe and Asia, and is more energy efficient than standard stovetops. However, recent studies warn about emissions from gas stoves inside homes.
Academic researchers and agencies such as the California Air Resources Board have reported that gas stoves can release dangerous pollutants while they are running and even when they are turned off.
A study conducted by American and Australian researchers in 2022 estimates that almost 13% of childhood asthma cases in the United States can be attributed to the use of gas stoves.
Dozens of US cities have adopted or are considering regulations that prohibit natural gas hookups in new construction homes after specific dates, to speed the transition from fossil fuels.
At least 20 states have adopted laws or regulations that remove bans on natural gas.
On January 9, 2023, the United States Consumer Product Safety Commission announced that consider measures to ban gas cookers or regulate hazardous emissions. He has yet to propose specific steps, saying any regulation “will involve a long process.”
As an environmental health researcher working on homes and their indoor ventilation, I have been involved in studies that have measured air pollution inside homes. I built models to predict how indoor sources would contribute to air pollution in different types of homes.
Here’s some perspective on how gas cookers can contribute to indoor air pollution and whether to stop using them.
One of the main air pollutants associated with the use of gas cookers is nitrogen dioxide or NO₂.
Exposure to nitrogen dioxide in homes has been associated with more severe asthma and increased use of rescue inhalers in children. This gas can also affect asthmatic adults and contributes to both the development and exacerbation of chronic obstructive pulmonary disease.
Nitrogen dioxide in homes comes from both outdoor air and indoor sources.
Vehicular traffic is the most important outside source: levels are highest near major roads. Gas cookers are often the most important indoor source.
The gas industry position is that stoves are a minor source of indoor air pollution. This is true in some homes. However, in many cases gas cookers contribute more to increasing nitrogen dioxide levels than outdoor sources.
For example, a study in southern California showed that about half of the homes exceeded a health standard based on the highest hour of nitrogen dioxide concentrations, almost entirely due to indoor emissions.
How can a gas stove contribute more to your nitrogen dioxide exposure than a whole highway full of vehicles? The answer is that outdoor pollution is dispersed over a large area, while indoor pollution is concentrated in a small space.
The amount of indoor pollution caused by a gas stove is affected by the structure of the home, which means that indoor ambient exposures to NO₂ are higher for some people than others.
People who live in larger houses, have range hoods that vent to the outside, and well-ventilated houses will generally be less exposed than people who live in smaller houses with poorer ventilation.
But even the largest homes can be affected by the use of gas cooktops, especially since the air in the kitchen doesn’t immediately mix with the cleaner air in the rest of the house.
Using an exhaust hood when cooking or other ventilation strategies, such as opening kitchen windows, can dramatically reduce nitrogen dioxide concentrations.
Nitrogen dioxide is not the only pollutant emitted by gas cookers. Some pollution with potential impacts on human health and the climate occurs when the stoves are not even working.
A 2022 study estimated that gas stoves in the United States that are not in use emit methane, a colorless and odorless gas that is the main component of natural gas, at a level that traps as much heat in the atmosphere as the equivalent of 400,000 cars.
Some of these leaks may go undetected. Although companies add scents to natural gas to make sure people smell leaks before there is a risk of explosion, the smell may not be strong enough for residents to notice small leaks.
Some people also have a much stronger sense of smell than others. In particular, those who have lost their sense of smell, whether due to covid or other causes, may not even smell large leaks.
A recent study found that 5% of homes had undetected leaks by their owners that were large enough to require repair.
This same study showed that natural gas leaks contained multiple dangerous contaminants, including benzene, a carcinogen. Although the measured concentrations of benzene did not meet thresholds of health concern, the presence of these substances in the air could be problematic in homes with substantial leaks and poor ventilation.
Reasons to change
If you live in a house with a gas stove, what should you do and when should you worry? First, do what you can to improve ventilation. This will help, but it won’t eliminate exposures, especially for household members in the kitchen.
If you live in a smaller home or with a closed kitchen, exposures can be dangerous even with good ventilation, especially if someone in the home has a respiratory disease such as asthma or chronic obstructive pulmonary disease.
Switching from a gas cooker to one that uses magnetic induction would eliminate this exposure. and at the same time it would provide benefits for the climate.
There are multiple incentive programs to support changes from gas stoves, given their importance in curbing climate change. For example, the recently signed Inflation Reduction Act of 2022, which includes provisions to address climate change, offers discounts for the purchase of high-efficiency appliances.
Some weatherization steps can reduce air leakage to the outsidewhich in turn can increase indoor air pollution concentrations if residents do not improve kitchen ventilation.
Even if you’re not motivated to reduce your carbon footprint, or are just looking for ways to cook pasta faster, the opportunity to have cleaner air inside your home can be a strong motivator to make the switch.
* Jonathan Levy is a professor and chair of the Department of Environmental Health at Boston University.
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