A recent Duke study raises concerns over Boston’s natural gas pipeline system.

Although the study was not originally assessing explosion risks in the pipeline system, the researchers found more than 3,000 gas leaks under Boston’s streets. The researchers also identified also six locations in Boston where explosions could potentially occur since gas concentrations exceeded a certain threshold.

“Repairing these leaks will improve air quality, increase consumer health and safety and save money,” Robert B. Jackson, co-author of the study and professor of global environmental change at the Nicholas School of the Environment, said in a press release. “We just have to put the right financial incentives into place.”

Leaks were distributed evenly across neighborhoods and were associated with old cast-iron pipes, the study found.

The researchers recommend using gas-leaks mapping campaigns in cities that are deemed at-risk for these leaks.

According to the U.S. Pipeline and Hazardous Materials Safety Administration, natural gas pipeline failures have caused on average 17 fatalities, 68 injuries and $133 million in property damage annually.

The leaks also pose a negative environmental and economic effect. The primary ingredient of natural gas is methane, which is a powerful greenhouse gas. Additionally, leaks in the United States contribute to $3 billion of lost and unaccounted gas each year.