Proposed Amended Rule 1143 – Consumer Paint Thinners and Multipurpose Solvents

Rule 1143 is designed to reduce volatile organic compound (VOC) emissions from the use, storage, and disposal of consumer paint thinners and multipurpose solvents that are not regulated by the California Air Resources Board (CARB). Proposed Amended Rule (PAR) 1143 partially implements Control Measure CTS-01: Further Emission Reductions from Coatings, Solvents, Adhesives, and Lubricants of the 2022 Air Quality Management Plan to phase out the use of para-Chlorobenzotrifluoride (pCBtF) and tert-Butyl Acetate (t-BAc) due to toxicity and public health concerns. PAR 1143 includes: 1) a prohibition pertaining to the manufacture, sale, and use of consumer paint thinners and multipurpose solvents with pCBtF, t-BAc, or cyclic, branched, or linear, completely methylated siloxanes (VMS) at future effective dates; 2) sell-through provisions to ensure that manufacturers, distributors, and end users are provided with adequate time to transition to products without pCBtF, t-BAc, or VMS, if needed; 3) an alternative compliance pathway based on Product-Weighted Maximum Incremental Reactivity (PW-MIR) VOC limits which provides additional reformulation flexibility by allowing substitution of lower-toxicity VOCs with known reactivity characteristics, rather than relying on exempt solvents; and 4) revisions for clarity and consistency with other South Coast AQMD rules, streamlined administrative requirements, minor editorial changes, and removal of outdated rule provisions. While no change to ozone formation potential relative to baseline conditions is expected since compliant formulations of consumer paint thinners and multipurpose solvents that do not contain pCBtF, t-BAc, or VMS are currently available and capable of meeting the established VOC emission limits, implementation of PAR 1143 will reduce the associated risk of exposure to emissions of pCBtF, t-BAc, and VMS for workers, nearby receptors, and the public.