There is no single statute called the California Clean Air Act. California’s clean air framework is a bundle of overlapping state laws anchored by the 1967 Mulford-Carrell Air Resources Act and extended by greenhouse gas laws like AB 32 and SB 32. Together they give California the country’s most aggressive air quality regime, enforced by the California Air Resources Board (CARB) and backed by a unique federal waiver that lets the state set vehicle emission standards stricter than federal rules.
What the Framework Is Made Of
The foundation is the Mulford-Carrell Air Resources Act, signed by Governor Ronald Reagan in 1967. It merged the Bureau of Air Sanitation and the California Motor Vehicle Pollution Control Board into CARB.1California Air Resources Board. History Health and Safety Code Section 39000 declares that Californians have a primary interest in the quality of their physical environment and that atmospheric pollution directly threatens public health. Section 39600 directs CARB to take whatever actions are necessary to carry out its powers,2California Legislative Information. California Code Health and Safety Code 39600 – General Powers and Duties and Section 39601 authorizes it to adopt standards and regulations through formal rulemaking.3Justia. California Health and Safety Code 39600-39619.6 – General Powers and Duties CARB sets statewide emission limits, runs testing programs, and enforces penalties.
CARB handles vehicle emissions statewide. Under Section 39002, roughly three dozen local and regional air quality management districts carry primary responsibility for pollution from stationary sources: factories, refineries, construction sites. If a district fails to meet its obligations, CARB can step in and take over enforcement.
On top of that structure, California layered its greenhouse gas laws:
- AB 32, the Global Warming Solutions Act of 2006, required the state to cut emissions to 1990 levels by 2020.4California Air Resources Board. AB 32 Global Warming Solutions Act of 2006
- SB 32, signed in 2016, raised the bar to at least 40 percent below 1990 levels by 2030.5California Legislative Information. SB 32 Senate Bill – Chaptered
- AB 1279 targets carbon neutrality by 2045.
The main enforcement tool behind those targets is the cap-and-trade program, launched in 2013. It places a declining annual cap on total greenhouse gas emissions from major sources. Companies emitting below their allowance can sell surplus credits; those exceeding it must buy allowances at quarterly auctions.4California Air Resources Board. AB 32 Global Warming Solutions Act of 2006 Auction revenue funds the Greenhouse Gas Reduction Fund, which pays for transit projects, affordable housing near transit, and other emission-cutting programs.
The Federal Waiver That Makes California Different
Federal law normally bars states from setting their own emission standards for new vehicles. California is the sole exception. Section 209 of the federal Clean Air Act (42 U.S.C. § 7543) requires the EPA to grant a preemption waiver to any state that regulated vehicle emissions before March 30, 1966, so long as the state’s standards are at least as protective as federal ones.6Office of the Law Revision Counsel. 42 US Code 7543 – State Standards Only California meets that date. The EPA can deny a waiver only if California’s determination was arbitrary, the state lacks compelling and extraordinary conditions justifying separate standards, or the standards conflict with federal vehicle-performance requirements.
Once California receives a waiver, Section 177 of the Clean Air Act (42 U.S.C. § 7507) allows other states to adopt California’s standards wholesale, provided they adopt rules identical to California’s at least two model years before the standards take effect.7Office of the Law Revision Counsel. 42 USC 7507 – New Motor Vehicle Emission Standards in Nonattainment Areas More than a dozen states have taken that option, giving California’s rules reach well beyond its borders.
The waiver process is politically charged. Administrations have granted, revoked, and reinstated California’s waivers more than once. In early January 2025, the EPA issued notices of decision on several California waiver requests, including the Advanced Clean Cars II regulations, while California withdrew certain others.8US EPA. Vehicle Emissions California Waivers and Authorizations Status can shift with a new administration, so anyone tracking a specific rule should check the EPA’s waiver page for current status.
Vehicle Standards and the 2035 ZEV Mandate
Every new car or light truck sold in California must meet the Low Emission Vehicle standards in Title 13 of the California Code of Regulations.9California Air Resources Board. Light-duty Vehicle Regulations and Test Procedures LEV III covered model years 2015 through 2025. LEV IV takes over with the 2026 model year and tightens exhaust limits for criteria pollutants further.
Layered on top is the Zero-Emission Vehicle mandate, now governed by Advanced Clean Cars II, adopted in 2022. The rule requires that 100 percent of new passenger vehicles sold in California meet zero-emission standards by the 2035 model year.10California Air Resources Board. Advanced Clean Cars The ramp runs on a fixed schedule:11California Air Resources Board. Section 1962.4 ZEV Standards 2026 and Subsequent Model Years
- 2026: 35%
- 2027: 43%
- 2028: 51%
- 2029: 59%
- 2030: 68%
- 2031: 76%
- 2032: 82%
- 2033: 88%
- 2034: 94%
- 2035 and after: 100%
Plug-in hybrids count toward the ZEV requirement, but can satisfy no more than 20 percent of the overall obligation.12California Air Resources Board. California Moves to Accelerate to 100% New Zero-Emission Vehicle Sales by 2035 Battery-electric and hydrogen fuel cell vehicles carry full credit. Manufacturers that fall short must buy credits from competitors or face penalties. The mandate applies to new-vehicle sales, not to vehicles already on the road.
Smog Check: What Vehicle Owners Must Do
The compliance obligation most Californians will actually feel is the Smog Check. Health and Safety Code Section 44000 directs the state to maintain a vehicle inspection and maintenance program that meets or exceeds federal clean air standards.13California Legislative Information. California Health and Safety Code 44000 Most gasoline, hybrid, and alternative-fuel vehicles must pass a Smog Check to renew registration.
Not every vehicle needs an inspection every cycle. The exemption rules:14Bureau of Automotive Repair. Smog Check: When You Need One and Whats Required
- Vehicles eight model years old or newer are exempt from the biennial Smog Check for registration renewal.
- For change-of-ownership transactions, the exemption window shortens to four model years or newer.
- Diesel vehicles have no model-year exemption.
- A Smog Check is required whenever a vehicle is first registered in California, regardless of age or fuel type.
Inspections must be performed at stations licensed by the Bureau of Automotive Repair. The state does not regulate inspection labor cost, but every station charges an $8.25 state certificate fee.14Bureau of Automotive Repair. Smog Check: When You Need One and Whats Required Call ahead for pricing.
If a vehicle fails, the owner must complete emissions-related repairs and pass a retest before the DMV will renew registration. Owners meeting income requirements may qualify for the Consumer Assistance Program to help cover repair costs. Driving on expired registration because of a failed Smog Check triggers late-registration penalties from the DMV. Those penalties are percentage-based: the state adds a percentage of the vehicle license fee, starting at 10 percent for 1–10 days late and climbing to 160 percent after two years, plus flat registration and CHP late fees that grow at each tier.15California Department of Motor Vehicles. Penalties Resolving a failed Smog Check quickly is almost always cheaper than letting the penalties stack.
Penalties for Violations
Violating California’s air quality laws carries real consequences. Under Health and Safety Code Section 42400, a general violation of any CARB or air district rule, regulation, permit, or order is a misdemeanor punishable by a fine of up to $5,000 or up to six months in county jail, or both.16California Legislative Information. California Health and Safety Code 42400 If the violation causes actual physical injury to a considerable number of people, the maximum fine rises to $15,000 and the jail exposure to nine months. Each day the violation continues counts as a separate offense, so exposure compounds quickly for ongoing noncompliance.
Those criminal penalties sit alongside civil enforcement. CARB and regional air districts can issue administrative citations, seek injunctions, and impose per-day civil penalties for stationary-source violations. Vehicle manufacturers falling short of ZEV percentages must buy credits or pay per-vehicle fines. Whether you run a refinery, sell cars, or just need to renew your registration, the framework has a mechanism aimed at your situation.