Proposed Amended Rule 1401 – New Source Review of Toxic Air Contaminants

The South Coast Air Quality Management District is updating its health-risk-based permitting requirements through Proposed Amended Rule 1401 to better protect public health by refining the regulation of toxic air contaminants emitted by new, modified, or relocated equipment. The rule incorporates updated risk values from the California Office of Environmental Health Hazard Assessment, adding nine new compounds to the list of regulated toxic air contaminants, adjusting the reference exposure level for one existing compound, and introducing 8-hour chronic hazard index requirements to assess short-term cumulative exposure risks. Outdated reference tables are being removed to align the rule with current scientific standards and improve clarity in compliance and evaluation processes. These changes reflect the latest understanding of health impacts from airborne toxins and will enhance the district’s ability to manage emissions more effectively. The amended rule will not apply retroactively to existing equipment or sources but will require enhanced air pollution control measures for new or altered operations involving polymeric Hexamethylene Diisocyanate, para-chlorobenzotrifluoride, or tertiary butyl acetate, which are now recognized as posing significant health risks. By tightening permitting standards for these substances, the rule aims to reduce airborne exposure among workers and nearby communities, ensuring that emissions are minimized through state-of-the-art control technologies. Implementation of PAR 1401 is expected to lead to measurable improvements in air quality and public health outcomes, particularly in densely populated areas within the South Coast Air Basin, while maintaining regulatory alignment with current risk assessment methodologies.