Over 5,893 natural gas leaks from old pipelines have been found in Washington, D.C., a latest study states.

Researchers at Duke University and Boston University found that some manholes in the city had methane concentrations as high as 500,000 parts per million of natural gas. This is nearly 10 times higher than the threshold for an explosion.

The researchers informed the authorities of the dangerous leaks but even four months later no action was taken. "Finding the leaks a second time, four months after we first reported them, was really surprising," said Robert B. Jackson, a professor of environmental sciences at Duke who led the study, in a press release. 

"Repairing these leaks will improve air quality, increase consumer health and safety, and save money," Jackson said. "Pipeline safety has been improving over the last two decades. Now is the time to make it even better."

Natural gas pipeline failures cause an average of 17 fatalities, 68 injuries and property damage worth $133 million, stated the U.S. Pipeline and Hazardous Materials Safety Administration.

Furthermore, the gas leaks can also pose harm to the environment as methane is found in these gases, one of the most powerful greenhouse gas that sometime even catalyzes ozone formation. 

"Methane emissions from these four leaks ranged from 9,200 to 38,200 liters per day for each leak -- that's comparable to the amount of natural gas used by between 2 and 7 homes," said Duke Ph.D. student Adrian Down, who contributed to the study, in a press release.

"We need to put the right financial incentives in place," added Jackson. "Companies and public utility commissions need help to fix leaks and replace old cast iron pipes more quickly." 

The findings of the research have been published in the peer-reviewed journal Environmental Science & Technology.