Google Earth Outreach, teaming up on the project with the Environmental Defense Fund (EDF), said the goal is to better understand potential hazards as well as the environmental impact of these chronic, low-level leaks, since the methane they emit is a big contributor to global warming.

The maps can be found here and represent the first phase of a pilot project that uses specially equipped Google Street View mapping cars equipped with the latest sensing and analytical technology. The EDF and researchers at Colorado State University spent two years experimenting with the system and developing analytical tools to not only locate, but also accurately assess the amount of gas escaping from even small leaks detected amid 15 million individual readings collected over thousands of miles of roadway.

The maps show that the older the infrastructure, the more leaks. Boston, for example, had a leak for every mile driven while the newer systems in Indianapolis showed a leak for every 200 miles. Leak rates in Boston and Staten Island were similar.

“Environmental quality is an issue that affects everyone. Making this information more accessible can make a meaningful difference in people’s quality of life,” said Karin Tuxen-Bettman, program manager for Google Earth Outreach. “This pilot project is meant to explore and understand the potential for EDF and others to map and visualize important environmental information in ways that help people understand both problems and solutions.”

The EDF said it is wants to better understand the impact of methane which has a 20 times greater impact on climate change than carbon dioxide over 100 years. It only represents about 9 percent of U.S. emission (compared to 82 percent for carbon dioxide) but is growing partly due to contributions from the oil and gas industry.

“New technology has given us vastly greater ability to make environmental data available for everyone to see, and to use that information to solve environmental problems by making better decisions,” the EDF’s Chief Scientist Steven Hamburg said. “Methane leaks are a pervasive challenge throughout the natural gas industry. This is an ideal chance to put new science to work and to solve a major real-world challenge.”

The dangers of leaks became readily apparent in March when a natural gas explosion brought down two East Harlem buildings in New York City and killed eight people. Since then, the city’s the New York City Fire Department has been given much greater leeway in responding to reports of leaks.

State and federal regulations require utilities to monitor their systems for safety. But the EDF said it can be difficult to determine just how much gas is escaping from a leak which means that “vast numbers” can go on for weeks or months without being repaired.

“We are taking action, accelerating natural gas pipeline replacement to reduce leaks while enhancing safety and reliability, and this kind of technology and data offers valuable insights,” said Susan Fleck, vice president, Pipeline Safety for National Grid. ”

Google Earth Outreach and the EDF plan to expand the project tracking methane leaks to other cities and start tracking other air pollutants.