Benzene found in gas piped to Calif. homes
The gas that is piped into millions of California homes contains hazardous air pollutants including benzene, a chemical linked to cancer, a new study found.
The researchers estimated that each year California gas appliances and infrastructure leak the same amount of benzene as is emitted by nearly 60,000 cars, but these leaks are unaccounted for in the state’s records.
The study, published Thursday in the journal Environmental Science & Technology, adds to a growing debate over proposals to limit the use of gas in homes because of its impact on climate change and public health. That issue has surfaced most notably in California, where in 2019 Berkeley became the first city to ban gas hookups in most new homes and buildings. Since then, dozens of cities in California and around the country have enacted similar ordinances.
Researchers have documented significant indoor air pollution and negative health impacts from using gas stoves. “Now we also know that even just having a gas appliance in your house can have health and climate impacts,” said Eric Lebel, the study’s lead author.
Several authors of the study, including Lebel, are senior scientists at PSE Healthy Energy, a nonprofit research institute focused on the public health and climate effects of energy production.
The study’s findings are not necessarily an immediate cause for concern for home cooks with gas ranges, but they can be an important consideration for homeowners who are preparing to replace appliances. Gas stoves are just one contributor to the indoor air pollution that many households live with every day. Smoking, some household cleaning products and fireplaces can all negatively impact indoor air quality.
Hard to detect
In the study, researchers collected 185 samples of unburned natural gas from 159 homes across California served by three gas companies: Pacific Gas and Electric, SoCalGas and San Diego Gas & Electric. Each of the samples contained air pollutants categorized as hazardous by the Environmental Protection Agency, meaning they are known to cause cancer and other serious health impacts.
The most prevalent of those pollutants was benzene, a highly flammable chemical that can be colorless and odorless, which makes it hard to detect when it leaks. Long-term exposure to significant amounts of the chemical can increase the risk of blood disorders and certain cancers like leukemia.
While the detected levels of the chemical in most of the samples were low, benzene accumulates in the body over a person’s lifetime, and health risks increase almost linearly with exposure, said Dr. Philip J. Landrigan, a pediatrician and public health professor at Boston College who was not involved in the study. “There is really no safe threshold” for benzene exposure, he added.
The new report builds on earlier studies from the same research group. In one study, researchers also detected benzene and other hazardous air pollutants in samples of unburned gas collected from residences in the Boston metropolitan area. In another study conducted in California, Lebel found that gas stoves leaked significant amounts of methane even when the stoves were turned off.
For the latest study, researchers combined the leakage findings with new measurements of benzene in unburned gas to model potential indoor benzene concentration levels. They found that in some of the worst cases, the concentration coming from the gas hookup was similar to that found in homes with smokers.
There are some factors that influence indoor benzene levels, like the quality of ventilation or the size of the kitchen. But this study found benzene in unburned gas, which suggests that “simply opening the windows or turning on a range hood while the stove is on” will not eliminate the risk, said Kelsey Bilsback, a senior scientist at PSE Healthy Energy.
Climate and health
Increasingly, environmentalists and local officials in states like California and Massachusetts have pushed to phase out gas appliances in favor of electric ones, mostly citing the emissions impact of burning fossil fuels like natural gas. Homes and buildings are directly responsible for about 13 percent of the country’s greenhouse gas emissions, mostly from gas burned in stoves, ovens, hot water heaters and furnaces.
Methane, the main component of natural gas, is a particularly potent greenhouse gas. If released into the atmosphere unburned, it can warm the planet more than 80 times as much as the same amount of carbon dioxide over a 20-year period.
The new research indicates that “health and climate go hand in hand,” said Drew Michanowicz, a senior scientist at PSE Healthy Energy. While it may not be feasible or affordable for some homeowners to make the switch immediately, energy policies that provide tax credits and rebates for electric appliances are a step in the right direction, he said.
Outside of smoking, “most of the major sources of benzene in our lives are associated with fossil fuels,” said Rob Jackson, an earth scientist at Stanford University who did not work on the study. Those sources include motor vehicle exhaust, gasoline, and products made with petrochemicals, like plastics, rubbers and detergents.
The growing body of evidence of harmful levels of indoor air pollution is a “good reason to encourage electrification not just for the climate, but for health, too,” he said.