Natural Gas Inside Homes Contains Toxic Compounds, Study Finds

A new study from the Harvard University T.H. Chan School of Public Health has found that the natural gas piped into homes for cooking and heating actually contains toxic volatile organic compounds, including chemicals linked to cancer.

Research from the Center for Climate, Health, and the Global Environment at Harvard (C-CHANGE) in collaboration with PSE Healthy Energy, Atmospheric and Environmental Research (AER), Gas Safety Inc., Boston University and Home Energy Efficiency Team (HEET), collected more than 200 unburned natural gas samples from 69 different kitchen stoves and building pipelines around Greater Boston from December 2019 to May 2021.

In the samples, the team found 296 chemical compounds, and 21 of these compounds are federally considered to be hazardous air pollutants, including benzene, toluene, ethylbenzene, xylene, and hexane. While the concentration of chemicals varied by location and time of year, the study generally found the highest concentrations of pollutants in the winter.

“It is well-established that natural gas is a major source of methane that’s driving climate change,” Drew Michanowicz, visiting scientist at Harvard Chan C-CHANGE and senior scientist at PSE Healthy Energy, said in a statement. “But most people haven’t really considered that our homes are where the pipeline ends and that when natural gas leaks it can contain health-damaging air pollutants in addition to climate pollutants.”

The study, recently published in the journal Environmental Science & Technology, also measured odorants in consumer-grade natural gas. These odorants give gas its well-known smell that alerts people to a leak. But the researchers found that with gas leaks 10 times higher than naturally occurring levels, there may not be enough odorant for people to detect the leak. These leaks can make both indoor and outdoor air contaminated with hazardous chemicals.

“This study shows that gas appliances like stoves and ovens can be a source of hazardous chemicals in our homes even when we’re not using them. These same chemicals are also likely to be present in leaking gas distribution systems in cities and up the supply chain,” said Jonathan Buonocore, co-author and research scientist at Harvard Chan C-CHANGE. “Policymakers and utilities can better educate consumers about how natural gas is distributed to homes and the potential health risks of leaking gas appliances and leaking gas pipes under streets, and make alternatives more accessible.”

More and more cities are already banning natural gas hookups in homes, and the researchers shared some actions for individuals and lawmakers to take to further reduce exposure to harmful pollutants coming from natural gas pipelines.

Among the policy recommendations, the team noted that both gas pipeline companies and utility companies need to measure, report and monitor natural gas composition, including odorant content. According to the scientists, there should also be more stringent performance standards for gas stoves and range hoods.

As for individual actions, the team recommends hiring a specialist to perform an in-home leak inspection and improving ventilation when cooking.