SCAQMD Rule 1124 2026 amendment: impact on solid film lubricants

This analysis covers South Coast AQMD Rule 1124 for solid film lubricants and dry lubricative materials on aircraft and space-vehicle parts. It does not cover other air districts or countries, non-aerospace lubricants, or worker exposure rules, and it is not legal advice for a specific product. Rule 1124 does not apply to aerosol coating products (South Coast AQMD Rule 1124, 2026), so aerosol solid film lubricants fall outside this phase-out.

What changed in SCAQMD Rule 1124 on April 3, 2026, and when does it apply?

The April 3, 2026 amendment of South Coast AQMD Rule 1124 added a phase-out of two VOC-exempt solvents, para-chlorobenzotrifluoride (pCBtF, CAS RN 98-56-6) and tert-butyl acetate (t-BAc, CAS RN 540-88-5), from aerospace materials, on a schedule that splits materials into Level I and Level II (South Coast AQMD Rule 1124, 2026). The amendment kept the existing VOC content limits for all aerospace material categories except the low-use adhesion promoter subcategory (CEQAnet, 2026).

For Level I materials such as lubricants, paragraph (f)(1) of Rule 1124 prohibits making, selling, possessing or applying a material "that contains pCBtF or t-BAc in concentrations greater than 0.01 percent by weight that was manufactured after the applicable Final Manufacture Date in Table 4" (South Coast AQMD Rule 1124, 2026). Any VOC-containing material added to the original product counts as part of it.

The timeline below shows the dates that bind solid film lubricant suppliers and users in the South Coast AQMD.

The key row for lubricant users is April 3, 2028: after that date, no pCBtF or t-BAc containing lubricant above 0.01% may be applied in the district, whatever its manufacture date, unless an exemption in subdivision (k) of Rule 1124 applies (South Coast AQMD Rule 1124, 2026).

Which solid film lubricant categories are Level I or Level II materials under Rule 1124?

All solid film lubricant and dry lubricative material categories in South Coast AQMD Rule 1124 are Level I materials, so none of them can use the Level II alternative compliance options. Rule 1124 defines Level I materials as those "where the use of para-chlorobenzotrifluoride (pCBtF; CAS RN: 98-56-6) and tert-butyl acetate (t-BAc; CAS RN: 540-88-5) will be phased out", and Level II materials as those where use "will conditionally be allowed" (South Coast AQMD Rule 1124, 2026).

In the published PDF, Table 1 places the check mark for every lubricant row in the Level I column: solid-film lubricant and dry lubricative material for fastener installation, the three fastener-lubricative coatings used in fastener manufacturing, and the two non-fastener lubricative coatings used in fastener manufacturing (South Coast AQMD Rule 1124, 2026). The staff report lists the same lubricant subcategories under Level I (South Coast AQMD staff report, 2026).

The staff report explains the split. Level I materials are aerospace materials that "either do not rely on pCBtF or t-BAc to meet current VOC limits or have readily available alternative formulations that can be adopted without extensive qualification testing" (South Coast AQMD staff report, 2026). Level II materials rely on the two solvents, particularly where military or OEM specifications require multi-year requalification. The Level II alternatives to the prohibition, an air pollution control system or a low-use permit condition (South Coast AQMD Rule 1124, 2026), therefore apply to Level II categories, not to lubricants.

What VOC limits does Rule 1124 set for solid film lubricants?

South Coast AQMD Rule 1124 limits solid film lubricants to a regulatory VOC content of 880 g/L for fastener installation and for non-fastener lubricative coatings, and to 250 g/L for fastener-lubricative coatings applied in fastener manufacturing (South Coast AQMD Rule 1124, 2026). Regulatory VOC is grams of VOC per liter of coating, less water and less exempt compounds, so a solvent that is exempt under Rule 102 does not count toward it.

Rule 1124 defines a solid-film lubricant as "a very thin coating consisting of a binder system containing as its chief pigment material one or more of the following: molybdenum disulfide, graphite, polytetrafluoroethylene, or other solids that act as a dry lubricant between faying surfaces" (South Coast AQMD Rule 1124, 2026). A fastener manufacturer, in the rule's terms, is a facility that coats aircraft fasteners such as pins, collars, bolts, nuts and rivets with solid-film lubricants for distribution to other facilities (South Coast AQMD Rule 1124, 2026).

The table below lists the affected lubricant products, their Table 1 limits and their pCBtF and t-BAc level.

The tightest solid film lubricant row is the 250 g/L limit for fastener-lubricative coatings in fastener manufacturing, which is where exempt solvents matter most (South Coast AQMD Rule 1124, 2026).

Why did South Coast AQMD phase out pCBtF and t-BAc in aerospace materials?

South Coast AQMD phased pCBtF and t-BAc out of aerospace materials because California's Office of Environmental Health Hazard Assessment (OEHHA) found both solvents to be potential carcinogens, after years in which they had been used to meet VOC limits. The staff report records that US EPA exempted pCBtF from the definition of VOC in 1994 and t-BAc in 2004, and that South Coast AQMD added pCBtF as an exempt compound under its Rule 102 in 2004 (South Coast AQMD staff report, 2026).

The toxicity findings came later. OEHHA finalized its t-BAc assessment in 2018, identifying it as a potential carcinogen, and in 2020 identified pCBtF as a potential carcinogen (South Coast AQMD staff report, 2026). Separately, OEHHA added pCBtF to the Proposition 65 list of chemicals known to the State of California to cause cancer, effective June 28, 2019, based on identification by the National Toxicology Program (OEHHA, 2019).

The board package for the amendment states the agency's position directly: "The California Office of Environmental Health Hazard Assessment has determined that para-Chlorobenzotrifluoride and tert-Butyl Acetate, which are used in certain aerospace materials, have carcinogenic health effects." (South Coast AQMD board package, 2026). Rule 1124 is one of seven South Coast AQMD VOC rules amended to address pCBtF and t-BAc, as listed in the August-September 2026 district newsletter, alongside rules for adhesives, solvent cleaning, metal parts coating and metalworking fluids (South Coast AQMD newsletter, 2026).

How does Rule 1124 compare with the federal aerospace NESHAP for solid film lubricants?

South Coast AQMD Rule 1124 is stricter than the federal aerospace NESHAP, 40 CFR Part 63 Subpart GG, for fastener-lubricative solid film lubricants, and the pCBtF and t-BAc phase-out is a South Coast AQMD measure, not part of the Subpart GG specialty coating limits. Subpart GG applies only to aerospace facilities that are major sources of hazardous air pollutants (eCFR, 40 CFR 63.741, 2026). Subpart GG Table 1 sets both an organic HAP limit and a VOC limit of 880 g/L for solid film lubricants and for dry lubricative materials (eCFR, 40 CFR 63.745, 2026). Rule 1124 matches 880 g/L for fastener installation but sets 250 g/L for fastener-lubricative solid-film lubricants in fastener manufacturing (South Coast AQMD Rule 1124, 2026).

Subpart GG names "molybdenum, graphite, polytetrafluoroethylene (PTFE), or other solids" as the chief pigment (eCFR, 40 CFR 63 Subpart GG Appendix A, 2026), while Rule 1124 names molybdenum disulfide.

Subpart GG exempts regulated activities for space vehicles, except depainting (eCFR, 40 CFR 63.741, 2026), while Rule 1124 applies to aircraft and space-vehicle products. Subpart GG exempts low-volume coatings up to 189 L (50 gal) per formulation and 757 L (200 gal) in total per year (eCFR, 40 CFR 63.741, 2026). Rule 1124 exempts formulations under 20 gallons per year, with a facility total under 200 gallons, but only from its VOC limits (South Coast AQMD Rule 1124, 2026). That exemption does not lift the pCBtF and t-BAc prohibition in subdivision (f).

What are the technical consequences of removing pCBtF and t-BAc from solid film lubricants?

For most solid film lubricants sold in the South Coast AQMD, removing pCBtF and t-BAc is a documentation task rather than a reformulation, because the staff survey reported that lubricants contained neither solvent (South Coast AQMD staff report, 2026). The district sent that survey on August 7, 2024 (South Coast AQMD PAR 1124 page, accessed 2026). Lubricants were not represented in the original survey responses, however, so a supplier cannot rely on it (South Coast AQMD staff report, 2026).

Where a product contains pCBtF, removal is hardest in the 250 g/L fastener-lubricative category, because an exempt solvent thins the coating without counting as VOC. Illustratively, 1.0 L of coating holds 100 g of VOC solvent and 300 g of pCBtF taking up 0.22 L: regulatory VOC is 100 / (1.0 - 0.22), about 130 g/L. Swap the pCBtF for the same mass and volume of a VOC solvent and the result is 400 g/L, over the 250 g/L limit (illustrative figures; formula from South Coast AQMD Rule 1124, 2026).

The 0.01% threshold also outruns the safety data sheet. Under the US OSHA Hazard Communication Standard, a carcinogen ingredient triggers classification of a mixture at a cut-off of 0.1% (OSHA, 29 CFR 1910.1200 Appendix A, accessed 2026), ten times the Rule 1124 threshold. An SDS that does not list pCBtF therefore does not show compliance. If a qualified product must change, industry told staff that reformulating aerospace coatings under military or OEM specifications can take decades (South Coast AQMD staff report, 2026).

What should solid film lubricant formulators and coaters do before the pCBtF and t-BAc dates?

Solid film lubricant formulators and coaters should confirm, in writing, that every lubricant and every thinner or additive used with it in the South Coast AQMD is at or below 0.01% by weight of pCBtF and t-BAc, and should track manufacture dates against the October 3, 2026, April 3, 2027 and April 3, 2028 deadlines (South Coast AQMD Rule 1124, 2026). The October 3, 2026 final manufacture date had already passed on 2026-10-14, so new lots must already comply.

The action table below assigns each step to a role and a deadline.

The coater's thinner check is easy to miss, because Rule 1124 counts any VOC-containing material added to the original product as part of that product (South Coast AQMD Rule 1124, 2026). Material shipped in only to be reformulated or repackaged for use outside the district, or stored and marked for use outside it, is exempt from the possession and repackaging prohibitions (South Coast AQMD Rule 1124, 2026).

What is still open in the Rule 1124 pCBtF and t-BAc phase-out?

Several points in the Rule 1124 pCBtF and t-BAc phase-out remain open as of 2026-10-14, and they matter more for proof than for formulation. First, Rule 1124 subdivision (i) names test methods for VOC and exempt compound content, including South Coast AQMD Test Methods 303 and 313, but it does not say which method shows a pCBtF or t-BAc content at or below 0.01% by weight (South Coast AQMD Rule 1124, 2026). Suppliers should ask the district which evidence it will accept.

Second, the board package asked the Governing Board to submit the amended rule for inclusion in the State Implementation Plan (South Coast AQMD board package, 2026). The sources checked for this article do not show whether US EPA has acted on that submittal.

Third, neighboring rules move on their own schedules. Rule 1144 for metalworking fluids and direct-contact lubricants sets a prohibition date of July 1, 2027, sell-through to July 1, 2028 and use-through to July 1, 2029 (South Coast AQMD timeline, 2026). The district's timeline, updated October 7, 2026, lists seven more rules proposed to phase out pCBtF, including Rule 1122 for solvent degreasers (South Coast AQMD timeline, 2026). A lubricant used on non-aerospace parts falls outside Rule 1124 and needs a check against the rule for that operation.

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