Air Toxics Hot Spots

The Air Toxics "Hot Spots" Information and Assessment Act (AB 2588, Connelly) was enacted in 1987, and requires stationary sources of pollutants to report the types and quantities of certain substances routinely released into the air. The goals of the Air Toxics "Hot Spots" Act are to collect emission data, to identify facilities having localized impacts, to ascertain health risks, to notify nearby residents of significant risks, and to reduce those significant risks to acceptable levels.

Guideline Values for Health Risk Assessment

Current Hot Spots Guidelines Technical Support Documents

Hot Spots Reports, Notices and Documents

May 4, 2018: Notice of Adoption of Reference Exposure Levels for Ethylene Glycol Mono-N-Butyl Ether
The adopted RELs cover different types of exposure to EGBE in air: infrequent 1-hour exposures, repeated 8-hour exposures, and continuous long-term exposure.
Jan 26, 2018: Extension of Public Comment Period for the Proposed Reference Exposure Levels for Toluene
OEHHA received a request from the to extend the public comment period. This notice extends the comment period to February 14, 2018.
Dec 19, 2017: Extension of Public Comment Period for the Proposed Reference Exposure Levels for Hexamethylene Diisocyanate
This notice extends the comment period to February 14, 2018.
Dec 5, 2017: Tertiary-Butyl Acetate (TBAc) Inhalation Cancer Unit Risk Factor (IUR) Document - Scientific Review Panel on Toxic Air Contaminants (SRP) Review Draft
This document will be reviewed and discussed by the Scientific Review Panel on Toxic Air Contaminants at its meeting on December 13, 2017 in Sacramento, CA.
Dec 1, 2017: Public Comment Period and Workshops on the Draft Reference Exposure Levels for Hexamethylene Diisocyanate and Toluene
The Office of Environmental Health Hazard Assessment (OEHHA) is releasing two draft documents for public review, summarizing the toxicity and derivation of proposed Reference Exposure Levels (RELs)
Feb 21, 2017: Notice of Adoption of Reference Exposure Levels for Carbonyl Sulfide
Adoption of Reference Exposure Levels (RELs) for carbonyl sulfide (COS) for use in the Air Toxics Hot Spots Program
Nov 14, 2016: Ethylene Glycol n-mono Butyl Ether (EGBE) RELs – Draft for Scientific Review Panel on Toxic Air Contaminants (SRP)
EGBE REL document revised in response to the comments made by the SRP during the March 4, 2016 meeting. The values proposed are: Acute REL: 4700 µg/m3, 8–Hour REL: 164 µg/m3, Chronic REL: 82 µg/m3
Nov 14, 2016: Tertiary-Butyl Acetate (TBAc) Cancer Unit Risk Factor (URF) Document - Scientific Review Panel on Toxic Air Contaminants (SRP) Review Draft
Revised draft document summarizing the carcinogenicity and derivation of an inhalation cancer unit risk factor (URF) for tertiary-Butyl Acetate (TBAc).
Sep 8, 2016: Notice of Adoption of Inhalation Cancer Unit Risk Factor for Perchloroethylene
Revised inhalation cancer Unit Risk for perchloroethylene is: 6.1 x 10-6 (µg/m3)-1, the inhalation Cancer Slope Factor is 2.1 x 10-2 (mg/kg-day)-1
Jun 28, 2016: OEHHA Acute, 8-hour and Chronic Reference Exposure Level (REL) Summary
Summary table of all OEHHA acute, 8-hr and chronic Reference Exposure Levels (chRELs) as of June 2016.  Documentation for these values is available in the Air Toxics Hot Spots Program Guidance Manual...

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