Methane leaking from municipal waste landfills into the atmosphere would be reduced under a regulation EPA proposed last week. The proposal, which is part of President Barack Obama’s Climate Action Plan, would by 2023 tighten controls on landfill emissions of methane, a greenhouse gas more potent than carbon dioxide (see box, page 14). It also would ratchet down releases of hazardous air pollutants from landfills. Under the proposal, landfill operators would have to install and operate a gas collection system. They could flare the captured methane, use it as fuel for a boiler or engine, or install a treatment system to process methane for sale or beneficial uses, EPA says. Landfills generate about 18% of U.S. anthropogenic methane releases, making them the nation’s third-largest source of methane emissions. Livestock and manure-processing emissions contribute 34%; oil and gas system leaks, 29%.