Environmental and health groups have filed a lawsuit against the Environmental Protection Agency for repealing its 2009 endangerment finding that greenhouse gases threaten public health. The lawsuit, filed in the US Court of Appeals for the District of Columbia Circuit, challenges the EPA's decision to eliminate emissions requirements for new vehicles and abandon federal climate regulations that have been in place for 17 years.

Plaintiffs including the American Lung Association, Natural Resources Defense Council, and Sierra Club argue the Trump administration is ignoring overwhelming scientific evidence linking climate change to deadly floods, droughts, wildfires, and hurricanes. The EPA claims its deregulatory action will save Americans $1.3 trillion by 2055, but critics counter that any savings from cheaper vehicles would be offset by $1.4 trillion in additional costs from increased fuel purchases, vehicle repairs, and public health impacts.

The groups warn that if the court sides with the EPA, Americans will face more pollution, higher costs, and thousands of avoidable deaths. Environmental advocates acknowledge the lawsuit is risky but necessary, as a court ruling against them could potentially reverse the 2009 Supreme Court decision requiring the EPA to regulate greenhouse gas emissions. The case represents a critical battle over the federal government's ability to address climate change and protect public health.