How California Air Quality and Pollution Control Districts Work

California’s air quality and pollution control districts are 35 regional agencies that regulate stationary sources of air pollution — factories, refineries, gas stations, dry cleaners, and any other fixed operation that releases contaminants into the air.¹ Each district issues permits, inspects facilities, writes local rules, and enforces them with civil penalties that can exceed a million dollars per day in the worst cases. If you operate equipment that emits pollutants, or you live near something that does, your local district is the agency that matters most.

Who Regulates What

California Health and Safety Code Division 26, Part 3 divides air pollution regulation between state and local authorities. The California Air Resources Board (CARB) handles mobile sources — cars, trucks, buses, and other vehicles. Local air districts handle everything that stays put.²

Sitting above both is the federal Environmental Protection Agency, which sets National Ambient Air Quality Standards for six criteria pollutants: carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter, and sulfur dioxide.³ CARB compiles district rules and state regulations into a State Implementation Plan and submits it to the EPA.⁴ Once the EPA approves a district rule into that plan, the rule becomes federally enforceable on top of its state authority.⁵

A single industrial facility in California can therefore answer to its local district, CARB, and the EPA at the same time. The practical result: the rules you follow depend on where you sit on the map.

How to Find Your District

The 35 districts are drawn around air basins rather than county lines. An air basin is a geographic area where terrain and weather cause pollutants to behave similarly. The San Joaquin Valley is walled off by the Sierra Nevada, and emissions there settle into a bowl that produces some of the worst ozone in the country. Coastal areas ventilate differently. Drawing district boundaries around these basins keeps one county’s pollution from becoming a neighboring county’s problem.

Some districts cover a single county. Others span many. The South Coast Air Quality Management District covers Orange County and the urban portions of Los Angeles, Riverside, and San Bernardino counties.⁶ The Bay Area Air Quality Management District covers nine counties around San Francisco Bay.

To identify the district that governs your address, use the statewide map CARB maintains linking every location to its district.⁷ Do this before anything else. The specific rules, fees, and forms you’ll deal with all depend on the answer.

Permits to Build and Operate

California Health and Safety Code Section 42300 authorizes every district to require permits before anyone builds, modifies, or operates equipment that could release air contaminants.⁸ There are two permits, and most operators underestimate the paperwork behind each.

The first is an Authority to Construct. You need it before installing or modifying any regulated equipment. Applications typically require maximum hourly throughput, fuel consumption rates, the chemical makeup of the materials you’ll handle, and engineering drawings of pollution control equipment such as scrubbers or catalytic oxidizers. You’ll also disclose the site location and its proximity to schools and hospitals, since those factors can trigger additional air quality modeling. Inaccurate stack heights, flow rates, or emission projections will get an application denied.

The second is a Permit to Operate. Once equipment is installed and tested, this permit confirms it actually performs within the limits set in the construction phase. Operating without it violates district rules even if you hold a valid Authority to Construct. Permits are extended year to year through review and fee payment, unless the district has moved to revoke.⁸

Every district publishes forms and fee schedules on its website. Larger and more complex projects cost significantly more than simple installations.

Title V Permits for Larger Facilities

Facilities that qualify as “major sources” under the federal Clean Air Act need a Title V operating permit on top of their district permits. The default threshold is 100 tons per year of any regulated pollutant. For hazardous air pollutants, the threshold drops to 10 tons per year for a single substance or 25 tons per year for any combination.⁹

In nonattainment areas, thresholds fall further for the pollutant the region is failing to meet. For volatile organic compounds and nitrogen oxides, the threshold drops to 50 tons per year in serious nonattainment areas, 25 tons in severe areas, and just 10 tons in extreme areas.⁹ The South Coast Air Basin and San Joaquin Valley carry extreme ozone designations, so facilities there can trigger Title V at emission levels that would be unremarkable in other states.¹⁰ Out-of-state companies expanding into California routinely miss this.

Inspections and Notices of Violation

District inspectors show up unannounced. They review maintenance logs, check sensor calibrations, look at visible emissions, and compare what the facility is actually doing against what its permit allows. When they find a violation, the facility receives a Notice of Violation.

The response window is shorter than most operators think. Multiple major districts require corrective action and a written response within 10 days.¹¹¹² Each additional day of noncompliance counts as a separate violation, and the totals compound quickly. Ignoring a Notice of Violation can lead to civil litigation or permanent revocation of the operating permit.

How Much Violations Cost

California’s civil penalty structure is tiered by the violator’s mental state, and the numbers are higher than many operators realize. Each amount is assessed per day of violation.

Strict liability: up to $5,000 per day for any violation of district rules, permits, or applicable code provisions, regardless of intent.¹³
Strict liability with a higher cap: up to $10,000 per day under a separate subsection, and up to $15,000 per day when the violation causes actual injury to public health.¹³
Negligent emissions: up to $25,000 per day, rising to $100,000 per day if the negligent emission causes great bodily injury or death.¹⁴
Knowing violations: up to $40,000 per day when a person knew of the emission and failed to correct it within a reasonable time, jumping to $250,000 per day when the knowing emission causes great bodily injury or death.¹⁵
Willful and intentional violations: up to $75,000 per day for deliberate emissions, up to $125,000 per day when the violation poses a risk of serious injury (up to $500,000 per day for corporations), and up to $250,000 per day when it causes great bodily injury or death ($1,000,000 per day for corporations).¹⁶

Those are the base statutory amounts. Since 2018, every maximum has been adjusted upward annually using the California Consumer Price Index.¹⁷ As of 2025, the cumulative CPI adjustment was 29.4%, pushing the strict liability ceiling from $5,000 to approximately $6,470 per day and the maximum corporate penalty for willful violations causing death from $1,000,000 to roughly $1,294,000 per day.¹⁸ The adjustments continue each year. Districts can also seek abatement orders that shut down equipment posing an immediate health threat.

Variances When You Cannot Comply

When a business genuinely cannot meet a district rule because of circumstances outside its control, it can petition the district’s Hearing Board for a variance. A variance is temporary legal protection from penalties while the business works toward a permanent fix.¹⁹

The Hearing Board must make all six findings in Health and Safety Code Section 42352 before granting one:

The business is violating, or will violate, a district rule or Section 41700, the general prohibition on discharges that cause injury or nuisance to the public.²⁰
Requiring compliance would result in an arbitrary taking of property or the practical shutdown of a lawful business, due to conditions the business could not reasonably prevent.²¹
Shutting down the business would not meaningfully reduce air contaminants.
The business has evaluated curtailing operations as an alternative.
The business will reduce excess emissions as much as feasible during the variance period.
The business will monitor and report emission levels on a schedule set by the district.²¹

Every variance petition requires a public hearing. The business must show not just that compliance is difficult, but that forcing it under the circumstances would be fundamentally unfair. Variances are temporary by design and carry conditions, including a concrete timeline for full compliance.

Filing a Complaint About a Local Source

Districts also respond to complaints from residents who experience smoke, dust, chemical odors, or other air quality problems from stationary sources. Most take complaints by phone, online form, or mobile app, and they treat caller information as confidential to the extent the law allows.²² Contact details help inspectors follow up, but many districts accept anonymous reports.

A district can only investigate sources within its own jurisdiction. If the source is a truck, a car, or something regulated by another agency, the district will redirect you. The quickest way to reach the right office is the CARB statewide map, which links every part of California to its local district website.⁷

1
California Air Resources Board. California Air Districts
2
California Air Resources Board. Ombudsman Business Assistance
3
U.S. Environmental Protection Agency. NAAQS Table
4
California Air Resources Board. California State Implementation Plans
5
U.S. Environmental Protection Agency. Basic Information about Air Quality SIPs
6
South Coast Air Quality Management District. Jurisdiction
7
California Air Resources Board. California Map for Local Air District Websites
8
California Legislative Information. California Code, Health and Safety Code HSC 42300
9
U.S. Environmental Protection Agency. Who Has to Obtain a Title V Permit?
10
U.S. Environmental Protection Agency. Current Nonattainment Counties for All Criteria Pollutants
11
Bay Area Air Quality Management District. Notices of Violations
12
Santa Barbara County Air Pollution Control District. Notices of Violation and the Mutual Settlement Program
13
California Legislative Information. California Health and Safety Code 42402
14
California Legislative Information. California Health and Safety Code 42402.1
15
California Legislative Information. California Code, Health and Safety Code HSC 42402.2
16
California Legislative Information. California Health and Safety Code 42402.3
17
California Legislative Information. California Health and Safety Code 42411
18
South Coast Air Quality Management District. Enforcement
19
California Air Resources Board. Variance Oversight Program
20
California Legislative Information. California Health and Safety Code 41700
21
California Legislative Information. California Code, Health and Safety Code HSC 42352
22
South Coast Air Quality Management District. Complaints