In February 2026, the US Environmental Protection Agency (EPA) rescinded its 2009 conclusion that greenhouse gases such as carbon dioxide and methane threaten the health and well-being of the American people.[4][5] This conclusion was in response to a 2007 US Supreme Court ruling that allowed these substances to be regulated under the Clean Air Act of 1970.[1][4] By overturning the finding, the EPA freed itself from the obligation to regulate greenhouse gas emissions.[1][5] The decision also abolished the standards for greenhouse gas emissions from vehicles.[4][7] EPA Administrator Lee Zeldin called the move the largest deregulation in American history.[5] Scientists and doctors around the world reacted with dismay to this decision.[1]