California Air Resources Board

CARB estimates premature death and other health effects related to PM2.5 exposure based on a peer-reviewed methodology developed by the U.S. Environmental Protection Agency (U.S. EPA, 2010).  The methodology is used to estimate the reduction in premature deaths and other health effects associated with emission reductions of PM2.5 emitted directly from sources and secondary PM2.5 formed in the atmosphere from chemical precursors.

CARB periodically updates the underlying air quality and demographic data to make sure it reflects current conditions. The most recent update was May, 2019.

A brief summary and a more detailed description of CARB’s methodology are available.  The basis for CARB’s methodology is described in Appendix J of the Truck and Bus Initial Statement of Reasons which was presented to the Board in 2010.  More information on the way the US EPA estimates health impacts of regulations can be found at the links below.

The following links provide more background information on the methodology for estimating health effects from PM2.5 exposure.

Methodology

• Summary - This page is an overview of the methodology for estimating health impacts.
• Detailed description - This page provides a detailed description of the methodology for estimating health impacts.
• Data - Contact CARB Research (Email: research@arb.ca.gov; Phone: (916) 445-0753) to obtain data used in the calculations.

CARB documents

• Truck and Bus Initial Statement Of Reasons Appendix J – This is a description of the methodology using 2006-2008 air quality data.

Documents related to U.S. EPA’s methodology

• Benefits Mapping and Analysis Program (BenMAP) – BenMAP is U.S. EPA’s software for estimating health effects associated with changes in air pollution levels.
• Technical Support Document: Estimating PM2.5- and Ozone-Attributable Health Benefits – U.S. EPA's approach to quantifying the number and value of health impacts attributable to changes in ambient PM2.5 and O3 exposure.
• Integrated Science Assessment for Particulate Matter – U.S. EPA’s assessment of relevant PM health studies that informs the review of the national ambient air quality standards for PM.

November 2022 Update – New and Updated Health Endpoints 

In November 2022, CARB staff released a bulletin providing a list of new and updated PM2.5 health endpoints to be used in CARB’s health analyses for plans and regulations, along with the scientific basis for choosing those endpoints and information on the valuation. These endpoints will be used in CARB health analyses for plans and regulations starting in early 2023. 

The new endpoints are as follows: 

• Cardiovascular emergency department visits
• Acute myocardial infarction (nonfatal) 
• Asthma onset 
• Asthma symptoms/exacerbation 
• Work loss days 
• Lung cancer incidence 
• Alzheimer’s disease 
• Parkinson’s disease 

The following endpoints have been a part of CARB’s routine health analysis methodology since 2010, but the underlying studies used for the effect estimate for these endpoints have been updated to more recent studies: 

• Cardiovascular hospital admissions 
• Respiratory hospital admissions 
• Respiratory emergency department visits (previously, CARB had specifically analyzed asthma but are updating this endpoint to include all respiratory diseases) 

This inclusion of new and updated endpoints is part of a larger project to expand CARB’s health analysis methodology in response to new research over the last decade. The project began in April 2020 when the Board directed staff, through Board Resolution 20-13 (Health Evaluation of Air Quality and Climate Regulations and Programs), to expand our health analysis approaches (e.g., updating the health endpoints) in order to capture a broader and more comprehensive range of benefits from reductions in air pollution.

• Board Resolution 20-13 (April 2020), “Health Evaluation of Air Quality and Climate Regulations and Programs” 
• Public workshop slides and recording (December 2021), “Evaluating New Health Endpoints for Use in CARB’s Health Analyses” 
• Updated Health Endpoints Bulletin (November 2022)