South Coast Air Quality Management District (SCAQMD) is proposing an amendment to Rule 1151, which controls volatile organic compounds (VOCs) and toxic air contaminant (TAC) emissions from automotive coating applications performed on motor vehicles, mobile equipment, and associated parts.
The Office of Environmental Health Hazard Assessment (OEEHA) determined that two exempt compounds, para-Chlorobenzotrifluoride (pCBtF) and tert-Butyl Acetate (t-BAc), have toxic endpoints. t-BAc was previously exempt from the definition of VOC in Rule 1151, and pCBtF is exempt from the definition of VOC in all rules in South Coast AQMD. Automotive coating manufacturers utilize these two exempt compounds to comply with SCAQMD Rule 1151 VOC limits. The proposed amendment to Rule 1151 aims to prioritize lowering the toxicity in the automotive coatings, though possibly result in higher VOC emissions.
The proposed changes in this amendment will go into effect starting May 1, 2025.
Applicability
Rule 1151 applies to any person who supplies, sells, offers for sale, markets, manufactures, blends, packages, repackages, possesses, or distributes any Automotive Coating, Automotive Coating Component, or associated solvent for use within the District South Coast AQMD, as well as any person who uses, applies, or solicits the use or application of any Automotive Coating, Automotive Coating Component, or associated solvent within the South Coast AQMD.
Requirements
Limits
The proposed amendment establishes new VOC content limits and effective dates for automotive coatings applied to motor vehicles, mobile equipment, or associated parts as shown in Table 1 below.
Table 1. Table of Regulatory VOC Content Limits and Effective Dates
| Coating Categories | Current Limits | Phase I1,2 | Phase II1 |
| g/L | lb/gal | g/L | lb/gal | g/L | lb/gal | Effective Date |
| Base Coatings |
| Color Coating | 420 | 3.5 | – | – | 250 | 2.1 | 1/1/2030 |
| Tinted Mid-Coat | 420 | 3.5 | 750 | 6.3 | 250 | 2.1 | 1/1/2030 |
| Clear Coatings |
| Gloss Clear Coating | 250 | 2.1 | 520 | 4.3 | 250 | 2.1 | 1/1/2030 |
| Matte-Clear Coating | 250 | 2.1 | 550 | 4.6 | – | – | – |
| Pretreatment Wash Primer | 660 | 5.5 | 780 | 6.5 | 660 | 5.5 | 1/1/2028 |
| Epoxy Primer | 250 | 2.1 | 580 | 4.8 | 340 | 2.8 | 1/1/2028 |
| Primer Sealer | 250 | 2.1 | 580 | 4.8 | 250 | 2.1 | 1/1/2029 |
| Primer Surfacer | 250 | 2.1 | 580 | 4.8 | 250 | 2.1 | 1/1/2029 |
| Other Coating Categories |
| Adhesion Promoter | 540 | 4.5 | 840 | 7.0 | 720 | 6.0 | 1/1/2028 |
| Single-Stage Coating | 340 | 2.8 | 600 | 5.0 | 340 | 2.8 | 1/1/2028 |
| Temporary Protective Coating | 60 | 0.5 | – | – | – | – | – |
| Truck Bed Liner Coating | 310 | 2.6 | – | – | – | – | – |
| Underbody Coating | 430 | 3.6 | – | – | – | – | – |
| Uniform Finishing Coating | 540 | 4.5 | – | – | – | – | – |
| Any Other Coating Type | 250 | 2.1 | – | – | – | – | – |
| 1 The specified limits remain in effect unless revised limits are listed in subsequent columns. |
| 2 Phase I is effective on the date of rule adoption. |
In addition to the new limits above, the following limits were also updated or added in the proposed amendment:
- Automotive coatings applicable to the Phase I and Phase II VOC limits must not contain more than 0.01 weight percent of either pCBtF or t-BAc.
- A new product-weighted MIR VOC Content limit of 1.50-gram O3 per gram VOC was added to reducers and thinners with an effective date on January 1, 2030.
- For Color Coatings, users may comply with an alternative VOC limit for coatings supplied in half-pint or smaller containers if the VOC content is no more than 720 g/L, and the color coating doesn’t contain more than 0.01 percent by weight of either pCBtF or t-BAc.
- For adhesion promoters and pretreatment wash primers, users can manufacture, supply, sell, or apply any adhesion promoter or pretreatment wash primers for use within SCAQMD that complies with the PW-IR limits in Table 2 below in lieu of the Table 1 Phase II VOC Limits.
Table 2. Alternative PW-MIR VOC Content Limits
| PW-MIR VOC Limits (g O3/g VOC) | Effective Date |
| Adhesion Promoters | 2.00 | 1/1/2028 |
| Pretreatment Wash Primers | 1.80 | 1/1/2028 |
Carcinogenic Materials and Exempt Compounds
The proposed amendment updates carcinogenic materials and exempt compound requirements for automotive coatings. The amendment prohibits the following chemicals in automotive coatings greater than the limits indicated:
- 1.0 ppm of cadmium
- 5.0 ppm of hexavalent chromium
- 0.1 percent by weight of Group II Exempt Compounds excluding volatile methylated siloxanes (VMS)
- 0.1 percent by weight of any VMS
- 0.01 percent by weight of pCBtF and t-Bac for automotive coatings and coating components subject to Phase I and Phase II VOC limits
- 0.01 percent by weight of pCBtF and t-Bac pursuant to effective dates in Table 3 below.
Table 3. pCBtF and t-BAC Prohibition Timeline
| Category | Prohibition Effective Date | Sell-through End Date | Use-through End Date |
| Color Coatings | November 1, 2025 | November 1, 2026 | January 1, 2028 |
| All Other Coating Categories | May 1, 2025 | May 1, 2026 | July 1, 2026 |
Sell-Through and Use-Through Provision Updates
The proposed amendment introduces sell-through and use-through provisions to phase out the use of pCBtF and t-Bac in automotive coatings. The amendment adds the following provisions:
- Any color coating manufactured prior to January 1, 2030 supplied in half-pint or smaller containers to comply with the alternative VOC limit of 720 g/L and that has a VOC content above 250 g/L, may be sold until January 1, 2030 and used until January 1, 2033.
- Automotive coatings manufactured prior to the effective date of the applicable VOC content limit in Table 1, that has a VOC content above that limit, may be sold for sale up to 24 months after the applicable effective date and use up to 36 months after the applicable effective date.
- Reducers or thinners manufactured prior to January 1, 2030, may be sold until January 1, 2032, and used until January 1, 2033.
Recordkeeping and Reporting Requirements
The proposed amendment adds a Quantity and Emission Report (QER) which requires manufacturers or private labelers of automotive coatings and coating components to submit a QER for automotive coatings and coating components sales according to the schedule below in Table 3.
Table 2. Alternative PW-MIR VOC Content Limits
| Reporting Deadlines for Manufacturers and Private Labelers | Reported Years |
| September 1, 2030 | 2028, 2029 |
| September 1, 2035 | 2033, 2034 |
| September, 2040 | 2038, 2039 |
The QER must contain the following information:
- Product Manufacturer
- Product Name and Code
- Applicable Rule 1151 category
- Actual and Regulatory VOC content
- Whether the product is waterborne or solvent-based
- Total annual volume sold into or within SCAQMD
- Indication if an automotive coating or coating component that exceeds the VOC limit has been sold under the alternative provisions.
The proposed amendment also adds a 5-year recordkeeping requirement for automotive coatings that exceed VOC limits by complying with alternative pathways listed in (f)(3) of the rule. Records required include information on the application method, mixing ratio, actual VOC content, manufacturer data sheets, and purchase records.
Additional Information
More detailed information on SCAQMD Rule 1151 can be found in the Draft Proposed Amended Language.
If you have any questions regarding the rule or maintaining compliance for your facility, please email Sydney Kwan, or Trinity’s Irvine office.
