South Coast AQMD to hold meeting on proposed additions to toxic air contaminant list

The South Coast Air Quality Management District (AQMD) will hold a working group meeting regarding the proposed amended rule 1401 (PAR 1401), which would add new toxic air contaminants, including compounds used in vehicle spray paints. 

The meeting will be held on Thursday, March 5, at 2:30 p.m. via Zoom and will provide stakeholders an opportunity to work with AQMD staff in the rule development process and to discuss key issues of concern, an email says. 

Use the Zoom link https://aqmd.zoomgov.com/j/1613163094 to attend the webinar with ID 161 316 3094. To dial in, call 1-669-254-525. 

The proposed amendment would add the following new compounds to Rule 1401: 

• • 1-bromopropane
  • Trivalent chromium
  • Parachlorobenzotrifluoride (PCBTF) 
  • Tertiary butyl acetate (TBAc)
  • Hexamethylene diisocyanate (HDI)
  • Polymeric hexamethylene diisocyanate
  • Cobalt 
  • Trimethylbenzenes

Hexamethylene diisocyanate, including monomer and polymeric, is described as an organic compound found in hardeners for automobile and airplane polyurethane spray paints, including primers, sealers, and clear coats, and coatings for outdoor furniture, parquet, and industrial wood, and architectural finishing. 

AQMD reviewed permits in 2024, according to documents in a presentation it gave that year, and found monomeric in less than or equal to 1% by weight. It found polymeric in higher concentrations, up to 62% by weight. However, documents note that a portion of the chemical reaction process may not become airborne. 

Trimethylbenzene is found in surface coatings, paints, printing inks, cleaning fluids, petroleum refinery distillation products (white spirit, high-flash-point naphtha, and gasoline), steel-making facilities, and coal-fired plants. 

Staff reviewed 77 coating applications and found it active in 27 applications, the documents say. About 25 applications had concentrations less than or equal to 5%. Tertiary butyl acetate is found in industrial coatings, inks, adhesives, industrial cleaners, and degreasers. 

A review of spray booths in eight facilities using products containing the compound had concentrations ranging from 3% to 68%. 

PCBTF is used in the preparation of dyes, pharmaceuticals, and pesticides, and serves as a solvent in paints, inks, and high-solids coating formulations, as well as for metal cleaning. 

Fifty-one spray booths showed they use the compound, including 24 autobody facilities, the documents show. It says concentration ranges from 3% to 100%. 

Staff evaluated an autobody spray booth permit application submitted in 2021 and found four compounds that could be used in the industry. 

A review of autobody spray booths found a large increase in cancer risk due to the compound. Coatings containing 50% PCBTF by weight would have to reduce the usage rate by 95% to comply with the risk limits in Rule 1401, the documents say. 

“In this example, a hypothetical future autobody spray booth permit application could be subject to permit conditions that would greatly limit product use unless an alternative product was available,” the documents say. 

For more information, visit the Par 1401 page here, or contact Tiffani To at 909-396-2738 or by email at [email protected].

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