What is the Department of Transportation required to do in the clean air act?

Under the Clean Air Act, the Department of Transportation (DOT) is required to ensure that federal vehicle and engine emission standards are established and enforced. The DOT must also collaborate with the Environmental Protection Agency (EPA) to develop fuel economy standards that help reduce greenhouse gas emissions. Additionally, the DOT is tasked with promoting transportation policies that support air quality improvements and compliance with national ambient air quality standards.