Leaks from gas stoves can create toxic levels of hazardous air pollutants

Low-level gas leaks from kitchen stoves, even when off, can create hazardous levels of benzene concentrations, researchers found in a study published in Environmental Science & Technology. The natural gas used to power millions of California homes contained benzene concentrations up to seven times higher than the state’s recommended exposure limit.

The report, co-authored by UC Berkeley School of Public Health Associate Researcher Seth Shonkoff and conducted by the nonprofit energy science and policy research institute PSE Healthy Energy —of which Shonkoff is executive director—found that California’s gas appliances and infrastructure leak the same amount of benzene as the emissions from nearly 60,000 cars each year.

“What has been largely overlooked until this study is that natural gas is not just methane but instead is a chemical cocktail that contains multiple hazardous air pollutants that pose risks to human health,” said Shonkoff. “Policies and measures that phase out gas appliances and stop natural gas leaks not only protect our climate, but our study shows that these approaches also provide important public health benefits by improving indoor and outdoor air quality.”

Researchers collected 185 individual samples of unburned gas across the state and found hazardous air pollutants in nearly every sample, including from three of the state’s major gas companies: Pacific Gas and Electric (PG&E), Southern California Gas Company (SoCalGas), and San Diego Gas and Electric (SDG&E).

Concentrations of pollutants varied throughout the state, with the highest levels found in Los Angeles County. Exceptionally high benzene concentrations were observed in the North San Fernando and Santa Clarita Valleys, where the study’s maximum benzene concentration of 66 ppmv was observed—a level roughly 30 times greater than the statewide average.

Last month, the state approved a plan to phase out the sale of gas appliances and water heaters by 2030 due to public health and climate concerns. California is also moving to end subsidies for connecting new homes to gas systems to accelerate the transition to electric alternatives.