Unprocessed natural gas is known to contain volatile organic compounds that can be harmful to human health, but few studies have examined their presence in the natural gas piped into homes. To address this knowledge gap, researchers analyzed the chemical composition of 234 unburned natural gas samples from 69 residential locations in the Boston area.
Their analysis, published in the July 19 Environmental Science and Technology, found trace amounts of volatile organic compounds, including 21 classified by the U.S. Environmental Protection Agency as hazardous air pollutants-"those known to cause cancer and other serious health impacts."
Benzene, a carcinogen, was found in 95% of the samples taken from cooking stoves and building pipelines; and other toxic chemicals, such as hexane and toluene, were detected at similar rates. The levels of hazardous chemicals found in the gas samples, which were collected over 16 months, varied according to the location and date of their collection and were higher in the winter. The researchers also found that concentrations of odorants added to the gas to alert users to leaks were inconsistent across samples, suggesting that small leaks could go undetected.
To lessen potential health risks associated with natural gas use, the study's authors recommend that individuals have their homes professionally inspected for gas leaks. They also suggest increasing ventilation while cooking by opening windows and using a range hood. At the policy level, the authors recommend tougher government regulation, including requiring natural gas companies to disclose the chemical composition of their products, establishing emission limits for stoves and range hoods, and strengthening odorization standards.
Some 42% of homes in the United States use natural gas, but this may change over time as concerns mount over the impact-including health effects-of climate change. Several cities, including New York, San Francisco, and Seattle, have moved to ban or curtail natural gas use in new construction. Natural gas is mainly composed of methane, emissions of which are a significant driver of global warming.-Diane Szulecki, editor