Air Toxics

Yolo-Solano AQMD’s Air Toxics Hot Spots Program requires certain facilities with the potential to emit certain amounts of toxic air pollutants to submit emissions inventories to the District and, in some cases, pursue risk reduction strategies.

The program is aimed at providing the public with information about potential health impacts from toxic air pollutants routinely emitted by facilities.

Districtwide Re-evaluation

The Office of Environmental Health Hazard Assessment (OEHHA) revised the Air Toxics Hot Spots Program Guidance Manual for the Preparation of Risk Assessments on March 6, 2015. The net result is that the calculated risk estimates for many sources have increased.

As a result of the change to the methodology, the District will be re-evaluating all facilities subject to the Hot Spots program.  The District held a public workshop on November 10, 2015 to discuss these changes. The District is sending out invoices to affected facilities, and will be collecting information necessary to calculate the prioritization scores for each facility.  If your facility is determined to be ‘low priority’ or ‘low risk’, there will be no additional invoices in future years.

Annual Report

State law requires districts to produce annual reports detailing local Air Toxics Hot Spots Program activities and facility listings.

2023 AB2588 Annual Report


The Air Toxics “Hot Spots’ Program was enacted by state law (AB 2588) in 1987.  The purpose of the law is to provide the public with information about the routine emissions and potential health impacts of toxic pollutants released to the air by facilities.

Certain facilities are subject to the program, and are required to submit a toxic emissions inventory.  With that data, the District calculates a prioritization score for each facility.  Depending on the prioritization score, some facilities are required to perform a health risk assessment.

Amendments to Air Toxics Reporting Programs

On January 1, 2022, the California Air Resources Board (CARB) adopted amendments to the Criteria and Toxics Reporting (CTR) Regulation. This amendment requires all facilities that emit more than 10 tons per year of any criteria air pollutant, except for carbon monoxide, to report annual emissions of criteria pollutants and toxics to CARB beginning with 2024 emissions data reported in 2025. Additionally, the amendment requires certain facility types, or facilities that use certain fuels or chemicals, to also report. These reporting facilities will be phased into the reporting requirements over the next five years.

On March 21, 2022, CARB also made effective amendments to the AB 2588 Air Toxics “Hot Spots” Emission Inventory Criteria and Guidelines Regulation (EICG). This amendment added to the list of chemicals that must be reported under the EICG and under Appendix E, adds the same facility types, or facilities that use certain fuels or chemicals, to align with the CTR Regulation above, including the phase in schedule. The EICG differs from CTR in that facilities subject to this regulation are also subject to the District fee Rule 4.9.

District Staff with work with facilities subject to CTR and the EICG to incorporate the requirements of this regulation into the annual throughput reporting currently collected.