A loophole in the Clean Air Act allows locomotives to remain in operation indefinitely, and many are 60-70 years old.

Source: https://www.deseret.com/opinion/2023/12/19/23997044/utah-inland-port-authority-growth-paradox

In response, Congress passed the Clean Air Act of 1970, which included a provision requiring all vehicles manufactured after 1975 to sharply reduce pollutants.

Source: https://www.nytimes.com/2023/11/14/us/catalytic-converters-thefts-recycling.html

The Biden administration is set to provide California with a waiver for its new rules, allowing it to enforce stricter guidelines than what were set out in the federal Clean Air Act, The Washington Post reported.

Source: https://dailycaller.com/2023/03/20/california-diesel-truck-ban-environmental-protection-agency/

The plan will establish rate-based limits on carbon dioxide emissions from coal- and gas-fired power plants, based on the agency’s assessment of the “best system of emission reduction” under the Clean Air Act.

Source: https://www.japantimes.co.jp/news/2023/05/08/world/us-carbon-capture-power-emissions/