OEHHA is responsible for conducting health risk assessments of chemical contaminants found in air, including those identified as toxic air contaminants or on the list of chemicals under the “Hot Spots” Information and Assessment Act. Assessments include development of Cancer Potency Factors to assess the cancer risk from carcinogens in air, and development of Reference Exposure Levels to assess noncancer health impacts. OEHHA has developed and updates risk assessment guidance for use in site-specific risk assessments under the Air Toxics Hot Spots program. OEHHA also makes health-based recommendations to the Air Resources Board for Ambient Air Quality Standards. Recent legislation, the Children's Environmental Health Protection Act, requires OEHHA to explicitly consider infants and children in evaluating health risks of air pollutants. OEHHA is evaluating current risk assessment methods for their adequacy to protect children.

OEHHA also conducts epidemiological investigations of the health effects of criteria air pollutants. Such investigations include the health impacts on sensitive subpopulations such as children and the elderly. For example, OEHHA conducted an evaluation of the impacts of traffic-related pollutants on children. Specifically, the relationship between respiratory health of children and proximity of their schools to heavily-traveled roadways including measured exposure to traffic-related pollutants was analyzed.

OEHHA also evaluates health effects of chemicals commonly found in indoor air. OEHHA participates in a number of inter-Agency activities designed to evaluate indoor air quality health issues and to move California toward safer indoor air quality.

OEHHA provides health-related assistance to the Air Resources Board, air pollution control districts, local health officers and environmental health officers.

Air Toxic Hot Spots

Current Hot Spots risk assessments and guidelines

Criteria Pollutants

Explore health-based recommendations for California's ambient air quality standards

Toxic Air Contaminants

Identification and evaluation to reduce exposure to air toxics

Epidemiological Studies

Examining real-life exposures in human populations, and how they relate to the incidence or prevalence of disease.

OEHHA Air Chemical Database

Get information on chemicals and their typical occurence/uses.

The Leggett Pharmacokinetic Model Code

AIR Leggett+ code download files are only useful for users who have MATLAB software loaded on their computer.


Reports, Notices, Documents

Aug 20, 2020: Notice of Adoption of Reference Exposure Levels for Toluene
The Office of Environmental Health Hazard Assessment (OEHHA) is adopting new Reference Exposure Levels (RELs) for Toluene for use in the Air Toxics Hot Spots Program. RELs are airborne concentrations of a chemical that are not anticipated to result in adverse noncancer health effects for specified exposure durations in the general population, including sensitive subpopulations.
Jan 28, 2020: p Chloro-α,α,α-trifluorotoluene (p-chlorobenzotrifluoride, PCBTF) Cancer Inhalation Cancer Unit Risk Factor (IUR) Document - Scientific Review Panel on Toxic Air Contaminants (SRP) Review Draft
The Office of Environmental Health Hazard Assessment (OEHHA) is releasing a draft document summarizing the carcinogenicity and derivation of a cancer inhalation unit risk factor (IUR) for p‑Chloro-α,α,α-trifluorotoluene (p-chlorobenzotrifluoride, PCBTF).  IURs are used to estimate lifetime cancer risks associated with inhalation exposure to a carcinogen.
Jan 7, 2020: Biogas and Human Health
2020 Recommendations to the California Public Utilities Commission Regarding Health Protective Standards for the Injection of Biomethane into the Common Carrier Pipeline.