Pennsylvania is aiming to curb air pollution and greenhouse emissions from its vast natural gas exploration fields, even as the Trump administration moves to relax federal requirements.
Democratic Gov. Tom Wolf's administration formally proposed new regulations Thursday that environmental groups welcome but also say should go farther in combating methane leaks.
Methane is the primary component of natural gas and is one of the most potent heat-trapping pollutants. Pennsylvania is the nation's second-largest natural gas producer after Texas.
The proposal would impose stronger limits on smog-forming pollutants and require companies to more aggressively search for methane leaks at existing oil and gas installations. A gas-industry trade group, the Marcellus Shale Coalition, says it's concerned about the cost for companies to comply.
Earlier this year, Pennsylvania began enforcing tougher standards on equipment at new or updated installations.