The US Environmental Protection Agency (EPA) has proposed a two-year delay on implementing an Obama era rule, due to have taken effect on Jun. 3, that would require oil and gas companies to detect and repair leaks of methane and other air pollution at new and modified drilling wells.

During the two-year period the agency said it needs to “review” issues associated with the rule’s requirements to limit methane leaks and their potential negative impact on oil and gas drilling activities, companies would not have to comply with the requirements.

The pertinent rules, known as the New Source Performance Standards, were finalized in 2016 as part of the then-federal government’s effort to reduce the release of methane, which is believed to have 25 times the warming potential of carbon dioxide. The oil and gas sector is considered to be the largest US industrial emitter of methane, which along with carbon dioxide is regarded as the second-biggest driver of climate change.

The EPA’s announcement provoked an outcry from the environmental movement, with the Environmental Defense Fund (EDF) saying the agency was acknowledging that the delay may make children sick.

EDF pointed to a section of the proposal that says the EPA acknowledges that the environmental health or safety risk addressed by this action may have a disproportionate effect on children’s health but “any impact would be limited because the length of the proposed stay is limited.” Other groups said the delay would endanger people living near industrial facilities.

Along with EDF, the Sierra Club and other environmental groups have filed a lawsuit against the EPA and its administrator Scott Pruitt, a declared climate skeptic, for illegally issuing a 90-day stay of the New Source Performance Standards, since extended to two years.  According to the Sierra Club, the lawsuit was the first to be filed against the Trump administration’s Environmental Protection Agency for attempting to suspend climate pollution reduction requirements.

Environmentalists say Pruitt wrote a letter to several oil and gas industry associations in April promising to postpone the deadline, bowing to complaints about the high cost of compliance. The environmental watchdog has calculated that the oil and gas industry could reap cost benefits of roughly $173 million through the two-year delay in implementing the methane emissions rule. EDF said the delay would result in an “increased release of methane and cancer-causing benzene.”

The Sierra Club’s chief climate counsel, Joanne Spalding, said in a statement released to US media that delaying implementation of the standards is illegal, as is extending the 90-day stay to two years. As attorney general of Oklahoma, Pruitt filed a lawsuit against the EPA challenging the rule.

The EPA will accept comments on the proposal for 30 days after publication in the Federal Register as well as on another Trump administration plan to delay implementation of a separate methane waste reduction rule issued by the Obama administration in late 2016.