Boston Gas Company

Bob Ackley, left, and Nathan Phillips measure methane levels on a Boston street. They found about 4, 000 significant gas leaks after driving 785 miles of Boston and suburban roads. Robin Lubbock/WBUR hide caption

toggle caption Robin Lubbock/WBUR

A scientist in Boston has been driving around the city measuring leaks in the gas mains. He's found a lot, and he wants the public to know where they are.

Gas leaks aren't uncommon, and gas companies spend a lot of time tracking them down and repairing them. But the scientific team says they're surprised at how many they've found, and what those leaks are doing to the health of the city's trees.

The project started after biologist Nathan Phillips at Boston University met a former gas inspector, Bob Ackley, on a stroll through town. Ackley was using a gas sniffer to look for leaks from underground gas mains. He told Phillips that Boston's gas system was leaky.

So Phillips obtained his own methane detector — a state-of-the-art model called a cavity ringdown spectrometer — and put it in a car. "We just measure while we drive, " he says. "It's a very fast-acting piece of equipment."

Nathan Phillips looks at methane data plotted on a map of Boston streets on Nov. 17. Data from a mobile methane "sniffer" and a GPS show a real-time display of the gas levels in Google Earth. The orange spike in the center of the screen, on St. Paul Street, indicates methane levels about two or three times above normal levels, Phillips says. Robin Lubbock/WBUR hide caption

toggle caption Robin Lubbock/WBUR

Nathan Phillips looks at methane data plotted on a map of Boston streets on Nov. 17. Data from a mobile methane "sniffer" and a GPS show a real-time display of the gas levels in Google Earth. The orange spike in the center of the screen, on St. Paul Street, indicates methane levels about two or three times above normal levels, Phillips says.

Robin Lubbock/WBUR

Together he and Ackley, who runs a company called Gas Safety USA, drove 785 miles of Boston and suburban roads. They found about 4, 000 significant leaks.

"Like many people, I really didn't know the scope of the problem, so I was very surprised, " says Phillips.

In some cases, the levels were high.

"The record level that we found for a leak — this is in the atmosphere on the surface in Boston — was about 30 parts per million of methane, " Phillips says, "and that's over 15 times the normal background level."

Phillips notes that he's not a health expert and says he has no reason to believe methane at those levels poses a risk to human health. But he does believe, as a plant physiologist, that the methane is probably harming trees.

"Natural gas is largely methane, " Phillips says. "That displaces the oxygen. It's also dry gas, so it desiccates the soils as well. And roots need to have oxygen for the metabolism of the roots, for repair of the root membranes. If they are starved of oxygen, the tree will suffer."

Fixing Up The System

A state advocacy group is suing utilities in the region for damages to trees and it's citing Phillips' research. The plaintiffs are communities that claim millions of dollars of damage has been done to trees in the Boston area.

Tom Kiley, head of the Northeast Gas Association, says it's true that methane can damage vegetation, but it's not common.

• Natural Gas companies
• New Mexico Gas Company
• Cleveland Gas Company
• Long Island Gas Company
• Ohio Gas Company