The Three Programs in One Paragraph Each

• Annual Emissions Report (AER). A local Air Quality Management District filing. Your district (SCAQMD, BAAQMD, San Joaquin Valley APCD, Sacramento, or one of the other 31 districts) collects yearly emissions data on criteria pollutants and toxic air contaminants from permitted facilities and from facilities on its notification list. SCAQMD runs AER under Rule 301; other districts have equivalent rules. The deliverable is filed through the district’s portal (AER-Web in the South Coast district). For the deeper guide, see our Annual Emissions Report (AER) California requirements piece.
• AB 2588 Air Toxics “Hot Spots” Inventory. A California-specific toxics program under the Air Toxics “Hot Spots” Information and Assessment Act of 1987, administered through local air districts. The deliverable most facilities owe is the Air Toxics Inventory Report (ATIR), a facility-by-facility accounting of toxic air contaminant emissions, used by the district to identify whether a Health Risk Assessment or public notification is needed. For the deeper view, see our AB 2588 air toxics reporting explainer.
• Criteria Pollutant and Toxics Reporting (CTR). A statewide California Air Resources Board regulation that pulls criteria pollutant and toxic air contaminant data into a uniform annual reporting framework across California. CTR is being phased in for facilities meeting specific operational and emissions criteria, and it is the program responsible for the Data Update Forms that many facilities receive in early January each year. Metal plating, anodizing, and grinding operations using cadmium or chromium are among the most commonly captured operations.

Side-by-Side Comparison

Use the table as a triage tool, not as a final determination. The applicability rules in each program have exceptions, and a single facility can owe one, two, or all three reports in the same year.

Where the Confusion Comes From

Three real situations we see during applicability reviews:

• A facility gets a notification letter from its district and assumes it covers everything. It usually covers one program. A SCAQMD AER notification does not satisfy AB 2588 reporting, and neither one waives CTR obligations.
• A facility sees a Data Update Form arrive in January and files it as if it were the AER. They are different programs with different forms. The Data Update Form is associated with CTR. The AER is a separate filing through your district’s portal.
• A facility files an AER, never hears about AB 2588 or CTR, and assumes neither applies. Silence is not a determination. AB 2588 and CTR are operations-driven; the absence of a letter does not establish exemption. When we walk a facility that operates plating tanks with cadmium or chromium, an anodizing line, or grinding on those metals, the first thing we check is whether CTR applies, regardless of whether a Data Update Form has appeared in their inbox.

The Plating, Anodizing, and Grinding Pattern

The clearest case of all three programs touching the same facility is in metal finishing. A California plating shop running hex-chrome tanks typically holds air permits, which triggers AER through the district. The same chrome chemistry triggers AB 2588 toxics inventory reporting because hexavalent chromium is a listed toxic air contaminant with sensitive-receptor implications. And the same operations now trigger CTR at the statewide level because plating, anodizing, and grinding with cadmium or chromium are explicitly in scope.

That single facility owes:

The reports share underlying data: amp-hours on the plating bath, abatement-device efficiency on the scrubber, material usage on the anodizing line, throughput on the grinding operation. They differ in form, in deadline, and in what the regulator does with them. Building the data once and routing it through three formats is the practical way to handle this without rebuilding the inventory three separate times.

How to Tell Which Apply to Your Facility

The fast version:

• Pull every air-related letter and form your facility has received in the last twelve months. Identify which agency sent each one and what program it references. District letterhead and CARB letterhead are different.
• List every emission source at the facility. Permitted equipment, unpermitted equipment, fuel-burning equipment, plating and anodizing tanks, abrasive blasting and grinding stations, spray booths, solvent operations.
• List every toxic air contaminant in your chemistries. Hex chrome, cadmium, nickel, lead, and similar listed metals are the most common CTR and AB 2588 triggers in our practice. Toxics in coatings, inks, and solvents matter as well.
• Cross-check your district’s notification list, the AB 2588 applicability criteria, and CTR’s operational scope against that source list. Any single trigger pulls in a program.

If the cross-check shows none of the three apply, document it in writing for your file. If it shows one or more apply, scope the work for the cycle you are already inside. District AER deadlines do not move once set (SCAQMD’s Data Year 2025 deadline is May 1, 2026), and CTR’s Data Update Form window in January is similarly tight.

Where This Piece Sits in Your Air-Reporting Picture

AER, AB 2588, and CTR are three of the moving parts in California’s air-emissions reporting framework. They remain three distinct programs with separate legal authorities and applicability triggers, but the picture is becoming more coordinated: CARB’s CTR regulation is being phased in over several years, some districts (including SCAQMD) collect CTR data through their existing AER process, and more facilities are being pulled into annual reporting as a result. For the broader view of what is changing and the timing, see our overview of California’s converging annual emissions reporting.

The underlying data foundation, an accurate source list, chemical usage by month, abatement efficiency, and throughput, is the same across all three reports. Build it once. Use it everywhere.