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

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: 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).
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
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...
Jun 10, 2016: Perchloroethylene Unit Risk Factor – Review Draft for Scientific Review Panel on Toxic Air Contaminants
The SRP Review Draft inhalation cancer Unit Risk for perchloroethylene is: 6.1 x 10-6 (µg/m3)-1, the Cancer Slope Factor is 2.1 x 10-2 (mg/kg-day)-1
Mar 28, 2016: Notice of Adoption of Reference Exposure Levels for Toluene Diisocyanate and Methylene Diphenyl Diisocyanate
Adoption of Reference Exposure Levels (RELs) for toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI) for use in the Air Toxics Hot Spots program. The REL values for TDI are: Acute: 2...
Feb 16, 2016: Public Comment Period and Workshops on Draft Inhalation Cancer Unit Risk Factor for Perchloroethylene
Revised potency values for PCE are based on the elevated incidence of several tumor types observed in male mice and rats.  Unit Risk Factor 6.1 E-06 (µg/m3)-1  Slope Factor 2.1E-02 (mg/kg-day)-1.
Feb 3, 2016: Ethylene Glycol n-mono Butyl Ether (EGBE) RELs - Scientific Review Panel on Toxic Air Contaminants (SRP) Review Draft
SRP Review draft for Ethylene Glycol n-mono Butyl Ether (EGBE) proposes the following guidance values:  Acute REL of 4700 (µg/m3); 8–Hour REL of 150 µg/m3; and a Chronic REL of 77 µg/m3.
May 21, 2015: Draft Reference Exposure Levels for Carbonyl Sulfide
After a comment period where no comments were received, OEHHA released its updated draft Reference Exposure Levels for carbonyl sulfide for its upcoming Scientific Review Panel meeting.

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