Methane leaks endanger cities.

• Position: Gas Explosions

High levels of natural gas are escaping from the aging pipes beneath the streets of the nation's capital, creating potentially harmful concentrations in some locations, a study published in Environmental Science & Technology has found. Natural gas leaks pose explosion risks, health concerns, and contribute to climate change.

Environmentalist Robert Jackson notes that natural gas leakage is a serious problem on multiple levels, including impacts on the economy and climate. Property damage is estimated at $133,000,000 annually and, by one estimate, gas customers in the U.S. between 2000-11 absorbed the cost of escaping gas to the tune of $20,000,000,000. On the global scale, leakage can contribute to climate change. Methane--the primary component of natural gas--is a potent greenhouse gas, far more so than carbon dioxide, and there is the potential threat to human life and health. On average, natural gas pipeline accidents in the U.S. kill 17 people a year. Also, methane can react with nitrogen oxides and spur the formation of ozone, which can aggravate asthma and other lung conditions.

Figuring out how to put a cap on leaks would mitigate these issues. First, though, researchers have to know where the gas is coming from. A previous study the team conducted in Boston, Mass., mapped out about 3,400 pipeline leaks along the city's 758 miles of roads. The researchers decided to make a...