Researchers led by Harvard T.H. found that samples of natural gas before it was used for cooking in Boston homes contained 296 chemical compounds. Report by Chan School of Public Health.
Toxic compounds included hexane (toluene), heptane (cyclohexane), benzene, and heptane. This is a known carcinogen. The researchers also found that the so-called “odorant level” added to natural gases as a safety precaution varied. Human noses could not detect this, which suggests that federal guidelines must be changed to address this problem.
These results were published in Environmental Science and Technology on Tuesday. They are part of a growing body research into the climate and health risks of natural gas.
The study comes as some cities, states, and provinces are moving to ban gas-fired appliances in new construction. In January, researchers at Stanford reported that methane leaks from residential gas stoves were far greater than previously thought and had a 20-year climate impact comparable to carbon dioxide emissions of half a million cars. They also warned that homes could be affected by combustion pollutants from gas stoves.
About half of all United States’ homes use natural gas for cooking and heating every day. Consumers are harnessing the energy from natural gas pipes hundreds of miles away from their original source with every click of the stove or turn of the thermostat.
Natural gas is mostly methane. This greenhouse gas has more than 80x the warming power of carbon dioxide over 20 years. But, when burned, methane produces less carbon dioxide than burning coal, leading to its promotion as a “bridge fuel” in the energy transition.
95 percent of the 234 samples from 69 homes contained low levels of benzene. This is linked to anemia and decreased immune function, as well as cancer. Drew Michanowicz, visiting scientist at the Center for Climate, Health and Global Environment and principal author of the new study, said that although benzene and other toxic chemicals raise questions about the health impact of natural gases in homes, it is not cause for panic.
The study examined the presence of hazards such as benzene within the natural gas before it was burnt, but not whether homeowners are exposed to these compounds.
Michanowicz stated the findings should be used to encourage scientists and energy experts, as well as health researchers, to examine whether natural gas is causing harm. “What are the costs of this system?” he asked.
Rob Jackson, professor of earth systems science at Stanford University, was co-author in the January study that revealed methane leaks higher than anticipated from gas stoves. He said that the Harvard research would give scientists and policymakers more data on indoor air pollution resulting from natural gas sources.
“This [new] study is a fascinating compliment to other studies on indoor pollutants generated in gas combustion,” Jackson said.
Current studies are looking into how much of each toxic component in natural gas homeowners are actually exposed to, and whether these amounts pose a serious health risk. Researchers stated that this is the first step in determining the health hazards for gas consumers. This includes stove use as well as natural gas leakage inside a home. One in 20 homes that were surveyed had gas leaks. Researchers recommended that consumers consult experts.
“There may be low level leaks in a lot of homes,” said Curtis Nordgaard, senior scientist at the research and policy institute PSE Healthy Energy, and a co-author on the new study. When the sum of them is added up across a metro area like Boston, he said, “it may be significant.”
The American Gas Association’s senior director of public relations, Jake Rubin, representing local energy companies that deliver natural gas, wrote in an email that “while combustion emissions from gas ranges, ovens, and cooktops can contribute to some degree to emissions of recognized pollutants, there are no documented risks to respiratory health from natural gas stoves from the regulatory and advisory agencies and organizations responsible for protecting residential consumer health and safety.”
Nordgaard suggested that occupational hazards might be more serious than home use. For example, commercial kitchen workers might be at greater risk of being exposed to gas-based hazardous compounds. Potential exposure can also be affected by the time of year. Boston saw eight-fold higher levels of hazardous compounds in winter than in summer.
Michanowicz stated that the winter peak could be due to a variety reasons. The winter season has a higher demand for natural gases to heat homes. This is due to people spending more time inside and less ventilation. Natural gas sources may change throughout the year, and different wells may have higher concentrations.
Beyond the potential impact on public health, the ability to identify the gas entering homes can influence decisions about climate change. “Cooking over natural gas flame is the most intimate connection with climate change that we never think about,” said Michanowicz.
The pipelines that start at fracked wells across the country “literally end where the kitchen begins,” he said. Methane, a greenhouse gas and the second most important contributor to global warming behind carbon dioxide, reached record levels in the atmosphere last yea. Stopping methane leaks into the atmosphere from stoves, water heaters and—most prevalently—pipelines and oil and gas wells, is critical to countering climate change.
Natural gas is pumped from gas wells located in western Canada or the southern United States to Boston. For the study, researchers focused on three major natural gas suppliers: the Algonquin Gas Transmission System operated by Spectra Energy Partners, Kinder Morgan’s Tennessee Gas Pipeline Company and the Maritime & Northeast Pipeline owned by Spectra Energy Partners, Emera Inc. and ExxonMobil.
Although methane is more potent than carbon dioxide by 80 times, it is also relatively short-lived. It stays in the atmosphere only for 20 years, while carbon dioxide remains in the air for hundreds of years. By cutting methane emissions as soon as possible, nations can achieve their goal of reducing global warming to zero by 2050.
What Can Be Done?
While switching to induction or electric stoves is the best way to avoid any potential harms from gas use, there are simple and affordable ways consumers can reduce their exposure. Zeyneb Magavi, coauthor of the Harvard study and executive director of Home Energy Efficiency Team, stated that while this is the best way to protect yourself, there are simpler, more cost-effective options.
Magavi advised using a rangehood that has ventilation to the outside for cooking on a gas stove. Ventilation can also be increased by opening windows if there are no vents.
Instead of replacing their gas stove immediately, consumers can plan to make the switch to an electric stove over time, and save money on a new appliance. Magavi suggested that an induction heat plate, which is inexpensive, can be used in homes with poor ventilation.
Magavi explained that improving ventilation and air filtration can be effective preventative measures.
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Magavi said that data and transparency are key to a better understanding of indoor air quality as well gas consumption. This includes information from natural gas companies on what is actually in consumers’ gas.
Jackson, a Stanford researcher hopes that utilities make more data about gas composition available to the public as a service. Companies publish information about the large components of their gas, such as hydrogen, oxygen, and sulfur. Other contents are classified under general impurities. However the chemical concentrations of these components are not as detailed as the Harvard study.
Magavi stated that identifying and fixing indoor gas leaks can reduce potential health risks and increase safety. Magavi said that residents and first responders may require more sensitive gas detectors to detect any gas leaks.
All samples in the study met federal standards for odorant levels. This is added to the gas to make dangerous leaks more easily detectable. The average methane content was still estimated by the authors using natural gas leakage data from the past. The current standard odor levels might not be sufficient to detect the average methane concentration from stoves. The study concluded that regulators should increase odorant levels to detect leaks currently going unnoticed.
Hannah Loss
Fellow
Hannah Loss is an American journalist who lives in New York City and Boston. She has interests in ecology, agriculture, and infrastructure. She is a graduate student at New York University’s Science, Health & Environmental Reporting Program. She previously worked in science documentary, radio production, and science conference programming. Tufts University taught her English and environmental studies.
Source: Inside Climate News
