The data on air pollution that we know periodically warn us of the poor quality of the air that a large part of the inhabitants of the cities breathe. Less data is known about another type of contamination that, on occasions, can become even higher and harmful to human health: that which is registered inside our homes.
A team of experts led by researchers from Stanford University (United States) has now thoroughly reviewed one of the sources of this type of air pollution inside homes: that which is produced by the combustion of gas in kitchens. (stoves, ovens).
"A chemical substance related to an increased risk of leukemia and other blood cell cancers sneaks into millions of homes every time residents turn on their gas stoves and stoves," the first paragraph of the information note published by the prestigious Stanford University to present the data from the study led by its experts. To ratify the importance of the study and its conclusions, it is also noted that its results have been published in the scientific journal Environmental Science
The toxic substance to which the study refers is none other than benzene, an aromatic hydrocarbon with the molecular formula C₆H₆. which can be released to the atmosphere by incomplete combustion or by natural gas or propane leaks.
In recent years, several studies have been published on this very problem, some of which have been conducted by experts at this San Francisco-area university; but the new research provides more concrete data and compares benzene levels with other pollutants. Thus, the new analysis led by Stanford experts finds that a single burner gas stove or gas oven set to 180ºC can raise indoor levels of the carcinogen benzene above those attributed to tobacco for passive smokers ( non-smokers who breathe smoky air from smokers).
Benzene also travels throughout the house and remains for hours in the air of the house, finds this new study.
Stanford graduate student Metta Nicholson prepares to test a gas stove in Bakersfield, California. (Image credit: Rob Jackson, Stanford University)
“Benzene forms in flames and other high-temperature environments, such as flares found in oil fields and refineries. We now know that benzene also forms in the flames of gas stoves in our homes," said the study's lead author, Rob Jackson, a professor of Earth system science at the Stanford Doerr School of Sustainability. “Good ventilation helps reduce concentrations of pollutants, but we found that exhaust fans were often not effective in eliminating benzene exposure,” notes Rob Jackson.
The researchers found that indoor concentrations of benzene formed in gas stove flames may be worse than average concentrations in secondhand smoke, that benzene can migrate to other rooms away from the kitchen, and that concentrations measured in bedrooms can exceed national and international concentrations (according to health benchmarks from organizations such as the WHO). The authors also found that residential range hoods are not always effective in reducing concentrations of benzene and other pollutants, even when the hoods are vented outdoors (ie, not exhausted into interior patios or similar rooms).
The new document is the first in California to look in detail at benzene emissions when using a stove or oven. Previous studies focused on leaks from stoves when they are turned off and did not directly measure the resulting benzene concentrations, Stanford University says.
The researchers now found that natural gas and propane burners and ovens emitted 10 to 50 times more benzene than electric resistance ovens and stoves. In contrast, the electric induction cooktops tested did not emit any detectable benzene. The rates of benzene emitted during combustion were hundreds of times higher than the benzene emission rates identified in other recent studies of unburned gas leaks in homes.
The researchers also tested whether food being cooked emits benzene and found zero benzene emissions from frying salmon or bacon. Thus, the authors indicate, all the benzene emissions that were measured in this study came from the fuel used.
An earlier study led by Stanford experts showed that gas-burning stoves inside US homes leak methane with a climate impact comparable to the carbon dioxide emissions of roughly 500,000 gasoline-powered cars. They also expose users to pollutants, such as nitrogen dioxide, which can trigger respiratory illness. A 2013 meta-analysis found that children living in homes with gas stoves had a 42% higher risk of asthma than children living in homes without gas stoves, and a 2022 analysis estimated that 12.7% of childhood asthma in the US is attributable to gas from stoves.
Study co-authors include Metta Nicholson and Colin Finnegan, environmental science research professionals in Stanford's Department of Earth System Sciences; Zutao Ouyang, a physical sciences research associate in Stanford's Department of Earth System Sciences; and researchers from PSE Healthy Energy, the University of California, Berkeley, and Lawrence Berkeley National Laboratory. The study was funded by the High Tide Foundation.
