WASHINGTON — Leon G. Billings, a former aide to Edmund Muskie and a key author of the Clean Air Act and other landmark environmental laws, has died.

Billings, 78, died Tuesday in Nashville, Tennessee, after suffering a stroke while visiting family.

As the first staff director of the Senate Environment subcommittee, Billings was a primary author of the 1970 Clean Air Act, one of the first and most influential environmental laws in U.S. history and a foundation for current air pollution laws.

Billings also played a key role in the 1972 Clean Water Act, the primary federal law governing water pollution.

He served as Muskie’s environment adviser and later was his chief of staff in the Senate and when Muskie was secretary of state. Billings also served in the Maryland Legislature.