Gas cookers contribute more to global warming than previously thought, as they constantly leak small amounts of methane even when turned off, a new to study found.
The same study also found that household stoves can emit high levels of nitrogen oxides, raising concerns about health and indoor air quality.
Even when not operating, US gas stoves emit 2.6 million tons (2.4 million metric tons) of methane – in units of carbon dioxide equivalent – into the air each year, a team of Californian researchers discovered in a to study published in the journal Environmental Science & Technology on Thursday. This is equivalent to the annual amount of greenhouse gases of 500,000 cars or what the United States emits into the air every three and a half hours.
This methane is in addition to the 6.8 million tonnes (6.2 million metric tons) of carbon dioxide gas stoves emit into the air when in use and the gas is burned, according to the study.
“We went into the study knowing that there would be emissions when the flames were burning, … but we didn’t expect to see such a large contribution from off emissions,” said University climatologist Rob Jackson. of Stanford and co-author of the study. study, told CBS News.
Methane is a greenhouse gas that is dozens of times more potent than carbon dioxide. Although it doesn’t last as long in the atmosphere and isn’t as abundant in the air, it has an outsized impact on climate change. About a quarter of the Earth’s warming so far can be attributed to methane, scientists have said.
The researchers looked at 53 home kitchens in California, many of them in guesthouses they rented. They sealed most of the rooms in plastic sheeting, then measured emissions when the stoves were on and when they weren’t. And they were surprised to find that most emissions occurred when the stoves were off. These are emissions that the Environmental Protection Agency ignores, Jackson said.
“Methane leaks all the way through the supply chain — it leaks from oil and gas wells, it leaks from pipelines — but very few people have measured emissions from stoves,” Jackson said.
However, the EPA plans to start tracking those emissions this year, an agency spokesperson in Washington said. To post.
“It’s a big deal because we’re trying to really reduce our carbon footprint and we’re saying gas is cleaner than coal, which it is,” said study lead author Eric Lebel. , scientist at PSE Healthy Energy, an Oakland nonprofit. Associated Press. But he said much of the benefit disappears when leaks are taken into account.
Methane leaks are not dangerous to human health unless the gas escaping is enough to cause an explosion, Jackson told CBS News.
But researchers have also found that high levels of nitrogen oxides, over 100 parts per billion, can build up within minutes of lighting a stove. Nitrogen oxides are irritants that can trigger asthma and breathing difficulties. Jackson said the EPA does not have indoor air quality standards for this gas, but the actions they have taken exceed its outdoor air quality standards.
The exact impact of nitrogen oxide emissions will depend on the size of someone’s kitchen and whether or not the cook uses their range hood while cooking. Most people don’t, Jackson said.
“I was the same, I never used my hood until we started this job,” he said. “Now I pester people – never light a burner without lighting the hood.”
Cities ban gas stoves
Many communities havein future new construction that will go into effect in the coming years, including New York City and the Bay Area cities of San Francisco, Oakland, San Jose and Berkeley. The gas industry has pushed back on these bans, saying gas appliances work better.
“People can already choose electric appliances if they want to,” said Frank Maisano, a Washington political and public relations expert who represents gas and appliance interests. “People like gas appliances because they work better, especially in colder climates.”
“Natural gas appliances are generally more energy efficient and more economical than their electric counterparts,” Maisano said.
The finding that methane leaks from homes matches other work that has foundaccounting for the majority of emissions, Zachary Merrin, a research engineer with the Illinois Institute for Applied Research’s Indoor Climate Research and Training Group, told the AP.
Merrin, who was not part of the study, said the emission of unburned methane is “clearly bad”. electric cooker.”
– Irina Ivanova of CBS News contributed reporting.