Summarized from the National Archives, Office of the Federal Register, https://www.archives.gov/federal-register/laws, and "The Legislative Process" visual guide from ProQuest's Legislative Insight.
For more about federal regulations and the CFR see:
ProQuest Congressional: Browse Topics > Air Pollution.
Westlaw Campus Research: Clean Air Amendments of 1970, United States Code Annotated Popular Name Table for Acts of Congress.
Westlaw Campus Research: 42 U.S.C.A. § 7411