The South Coast Air Quality Management District is proposing to phase out the use of p-chlorobenzotrifluoride and tert-butyl acetate in metalworking fluids and direct-contact lubricants through an amendment to Rule 1144, a long-standing regulation governing lubricant formulations in Southern California.
The move reflects a shift in regulatory priorities toward toxic risk reduction, with potential implications for lubricant suppliers operating in and beyond the region.
Under the proposal, manufacturers would be barred from producing products containing more than 0.01% by weight of either solvent after July 1, 2027, followed by a sell-through period ending July 1, 2028, and a final use prohibition after July 1, 2029.
The proposal matters because Rule 1144 has historically influenced formulation strategies well outside the South Coast Air Basin, given the district’s size, regulatory reach and role as a bellwether for state and national compliance. South Coast AQMD regulates air quality for more than 17 million residents across Los Angeles, Orange, Riverside and San Bernardino counties, an area that includes one of the largest concentrations of manufacturing, aerospace and metalworking facilities in the United States. Requirements adopted there are often mirrored by lubricant marketers seeking to maintain a single national product portfolio.
Unlike earlier rulemakings aimed at reducing ozone formation, the proposed amendment is driven by health assessments rather than photochemical reactivity. Both p-chlorobenzotrifluoride and tert-butyl acetate were previously classified as VOC-exempt solvents, but evaluations by California’s Office of Environmental Health Hazard Assessment identified carcinogenic risks associated with each. The amendment would not tighten existing mass-based VOC limits, which are typically 50 grams per liter for many affected categories, but would eliminate the ability to use these solvents as exempt compliance tools, requiring reformulation through alternative exempt chemistries, maximum incremental reactivity approaches or water-based technologies.
South Coast AQMD staff have said surveys conducted during the rulemaking process indicate manufacturers responding to the agency’s questionnaire are not currently using either solvent in products subject to Rule 1144, framing the proposal as a preventive measure. As staff outlined in briefing materials, the intent is to avoid future reliance on these compounds while allowing time for inventory clearance and reformulation using options such as water-based systems and “super-compliant” technologies that already meet existing VOC limits without toxic trade-offs.
The proposed amendment is part of a broader district program to remove p-chlorobenzotrifluoride and tert-butyl acetate from multiple regulatory categories, following similar prohibitions adopted for coatings, adhesives, and solvent cleaning operations. A public workshop on the preliminary draft rule language and staff report is scheduled for Jan. 28, 2026, to be held via webinar, with a Governing Board hearing expected in the second quarter of 2026. Industry observers note that, as with prior South Coast AQMD actions, the outcome could shape lubricant formulation strategies well beyond California.