California’s long fight for clean air is facing a major challenge after the U.S. Senate moved to question its right to set its own vehicle emissions rules. At the core is the 1970 Clean Air Act waiver, which “allows the state to enforce stricter pollution standards than federal rules.” This special exemption helped California tackle its severe smog problem and push the country toward cleaner technology.

More than a dozen states have since adopted California’s tougher standards, including zero-emission vehicle mandates that helped drive the EV boom. Critics warn that undoing these rules “could slow clean energy progress and worsen air quality.”

Environmental groups argue the Senate’s move threatens public health, especially for low-income and minority communities near highways and factories. In cities like Los Angeles and Fresno, asthma and heart disease rates remain among the nation’s highest.

Supporters of California’s policies, including Tesla and Google, say strict standards “boost innovation, create jobs, and enhance U.S. competitiveness.” Opponents, backed by fossil fuel interests, have spent millions lobbying against them.

Analysts caution that resisting clean energy may hurt lawmakers politically, as “younger and moderate voters increasingly support climate action,” and even conservative states now profit from renewables.