It's official: Washington, D.C., is full of hot air.
Nearly 6,000 natural gas leaks were discovered beneath the streets of the nation's capital last year when a team of researchers from Duke and Boston universities surveyed all 1,500 miles of the city's roadways, according to an article published Thursday in the journal Environmental Science & Technology.
A dozen were leaking enough methane to explode, while others were letting off enough gas to fuel from two to seven homes.
And four months after telling city officials about the leaks, the team returned and found that nine "were still emitting dangerous levels of methane," the team said in a statement.
"I was surprised. I was more than surprised, I was shocked," says Duke environmental sciences professor Robert Jackson, who led the study.
Jackson and about five other researchers drove the city's roadways in January and February of 2013, using a precise sensor and a GPS device to map the gas leaks. In all, they found nearly 5,900.
They stopped and took further samples at 19 especially heavy leaks, finding that 12 of them were pushing out enough gas to blow up.
All it would take, Jackson says, is "an electrical short. It would take a match dropped into the manhole or a cigarette butt."
Jackson says he called the utility Washington Gas to report the leaks, but when he and his team revisited the 19 sites in June, they found that nine still had not been repaired.
"Those very high concentrations are dangerous, they need to be fixed," the professor says.
Washington Gas did not immediately return a call for comment Friday. In a statement to USA Today, Eric Grant – the company's vice president of corporate relations – said he had not reviewed the study but that the company "immediately responds to every report of natural gas odor."
Washington Gas "repairs leaks seven days a week, 24 hours a day, 365 days a year," he said. "With over 13,000 miles of distribution mains and more than 940,000 service lines in our system, it is not realistic to state that there are no leaks."
Jackson emphasized that he wants "the message of this paper to be positive: If you fix these leaks, you save people money, you improve safety and air quality, and reduce greenhouse gas emissions."
About 17 people are killed and 68 injured each year from leaky natural gas pipelines, Jackson and his team said, citing figures from the U.S. Pipeline and Hazardous Materials Safety Administration. Leaks and explosions also cause an average of $133 million in property damage annually.
On average, pipelines across the country lose about 1.6 percent of the natural gas they transmit. The pipelines in D.C., by contrast, were losing about 4 percent of their gas. These findings, Jackson says, highlight "the opportunity to fix them."