I love my gas range. Nothing can compare to the beauty of cooking over that beautiful blue flame. The firepower can be quickly adjusted by gently turning the knob to perfectly match the cooking needs. There is even a saying in English such as "cooking with gas" to mean that everything is going well. However, environmentalists have warned in recent years that gas stoves are harmful to the climate and harmful to people's health. Two studies published this year have heightened concerns about harmful gases in the kitchen. Is this evidence enough to change people's cooking habits? For me, yes - but not too much, and others will need to make their own judgments.
Broadly speaking, there are two types of concerns about gas stove emissions. The first is that unburned natural gas can escape before the flame ignites, or leak from equipment connections. More than 90% of the gas leaked in this way is methane. The second is that combustion after ignition will produce pollutants, the most influential of which is nitrogen oxides that can irritate the lungs.
In a study conducted by environmental scientists at Stanford University in the United States, the amount of unburned gases that leaked into the kitchen when the gas stove was turned off was alarming. They found that more than three-quarters of the methane leaking from gas stoves leaked when they were not in use. The most likely cause of the leak was that the sealing degree of the joints of the pipes was not up to standard. Rob Jackson, the study's lead author, said that of the 53 gas stoves measured in the study (and many more the team later measured), only 1 did not leak when turned off. Methane is not toxic but is a powerful greenhouse gas. There are 40 million gas stoves in the United States. Jackson and the study co-authors estimate that these stoves release a large amount of methane every year, with a heat-absorbing capacity equivalent to the carbon dioxide released annually by 500,000 gasoline-powered cars.
The Stanford study also looked at the amount of nitrogen oxides produced when gas stoves are used. In a home without an exhaust device, a small kitchen, and poor ventilation, the amount of nitrogen oxides produced in a few minutes can exceed the nitrogen dioxide exposure limit set by the U.S. Environmental Agency (EPA), which is one billion per hour. Parts in 100 (100ppb, this is the outdoor value, the EPA does not stipulate safety standards for indoor nitrogen oxides). Even short-term exposure to excess nitrogen dioxide can worsen symptoms in people with respiratory problems. There is clear evidence that prolonged exposure increases a person's risk of developing asthma.
Another study, set in the greater Boston area, involved non-methane components in unburned gases from gas stoves. The study found 21 trace chemical ingredients considered harmful by the EPA, including volatile organic compounds (VOCs) such as benzene. The amounts of these ingredients are small, but the impact they have should be taken more seriously. Study leader Drew Michanowicz, a senior scientist at PSE Healthy Energy, a non-profit research and policy organization, said, “Now that many people are working from home, we breathe about 20,000 breaths a day. This time, my gas stove was about 3 meters away from me. What else is in the natural gas?" Michanowitz is also worried that more and more people are sealing up the windows of their houses to keep out the cold. "This will reduce gas exchange. , meaning indoor air pollution will be more serious."
Not surprisingly, the American Gas Association condemned both studies. Richard Meyers, vice president of the Gas Association, said the authors of the Boston study "did not indicate a health risk" and that the VOC levels they found were "reassuringly low." For the Stanford study, Meyers also believes the nitrogen oxide measurement method was inappropriate because plastic sheets were used to enclose a small space around the gas stove. Jackson responded that they only used encircling spaces to help measure the rate of gas leaks in very large kitchens, and that their team's assessment of health risks was based on measurements in open, unenclosed kitchens.
As ordinary home cooks, where should we go from here? Maybe listen to Michanowitz and buy an induction cooktop, which can do most of the cooking. Jackson hopes the government can provide incentives to encourage people to switch to electric stoves. Some U.S. cities are reducing the use of natural gas (for gas stoves and heating) in new buildings. As for me, I am changing too. I've switched to using an electric kettle to boil water, and even though it's noisy, I've used a range hood over the gas stove - something only 25% to 40% of people say they do. Weather permitting, I will also open a window.