Biennial Report on Air Quality Trends
and Emission Control Programs

This page last reviewed July 11, 2012

Section 39604 of the California Health and Safety Code requires the ARB to post on its Web site, each odd numbered year, information on air quality conditions and trends statewide and on the status and effectiveness of state and local air quality programs. This Web page provides links to detailed information that addresses the provisions of this requirement.

Air Quality Trends

The Almanac of Emissions and Air Quality is a report published annually that provides detailed information on historical air quality trends in California, in addition to the most current air quality data for which completed data are available. In addition, the Almanac summarizes the violations of air quality standards that have occurred over the most recent 20-year period. Information is provided for the State as a whole, for each air basin, as well as for each county comprising an air basin. The Almanac includes updated information on revisions to State and federal air quality standards, designations for State and/or federal standards, and State emission control program milestones. The Almanac also provides detailed information on emission trends and emission and air quality data related to toxic air contaminants.

Almanac of Emissions and Air Quality

The most current version of the Almanac is available for download in PDF format. All data tables in the Almanac can be downloaded as a text or Excel file through this Web Page.

ARB Research Projects

The ARB sponsors a comprehensive program of research into the causes, effects, and possible solutions to the air pollution problem in California. The goal of the research program is to provide the timely scientific and technical information needed to develop and support the public policy decisions required for an effective air pollution control program.

Status of Research Projects Summaries of ongoing and completed research projects, as well as final reports, are available for viewing and downloading.

Significant Federal Actions

The U.S. Environmental Protection Agency s (U.S. EPA) recent air quality-related actions with a California impact have been in three broad areas. The first is federal action on California air quality plans and rule updates submitted by the Air Resources Board to meet federal ambient air quality standards for 1-hour ozone, particulate matter (PM10), and carbon monoxide. This also includes changes to the attainment status of California regions with respect to federal standards. The next area is U.S. EPA s actions to set new ambient air quality standards for 8-hour ozone and fine particulate matter (PM2.5) and to establish implementation rules for those standards. The third area is major new federal control measures and programs intended to reduce pollution from sources like diesel engines and equipment and electric utilities.

Rule and Planning Activities at U.S. Environmental Protection Agency, Region 9 Region 9: Air Programs summarizes U.S. EPA s recent action on California State Implementation Plans and area classifications for 1-hour ozone, PM10, and carbon monoxide. A searchable database is available listing the status of all U.S. EPA action on air district rules.
New Federal Standards 8-hour Ozone Designations summarizes the California regions U.S. EPA designated as nonattainment for the 8-hour standard. The 8-hour Implementation Rule-Phase 2 lays out the process U.S. EPA has defined for the transition from the 1-hour to the 8-hour standard.
PM2.5 Designations summarizes the California regions U.S. EPA designated as nonattainment for the annual and 24-hour PM2.5 standards.
Transportation Conformity Regulations provide information on federal conformity procedures under the 8-hour and PM2.5 standards.
Federal Control Measures and Programs The Clean Air Rules of 2004 summarize U.S. EPA s major 2004 air-related rulemaking activities, including on the Interstate Clean Air Rule, the Mercury Clean Air Rule and the Nonroad Clean Air Rule.
West Coast Diesel Emissions Reduction Collaborative summarizes a new incentive-based initiative to reduce diesel emissions along the West Coast.

State Implementation Plan Status and Significant District Actions

Federal clean air laws require areas with unhealthy levels of ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, and inhalable particulate matter to develop plans, known as State Implementation Plans (SIPs), describing how they will attain national ambient air quality standards. State law makes ARB the lead agency for all purposes related to the SIP. ARB is also responsible for developing SIP elements for mobile sources and consumer products. Local air districts prepare SIP elements for sources under their authority to control and submit them to ARB for review and approval. ARB then forwards the combined State and local elements to U.S. EPA for approval.

Status of State Implementation Plan State Implementation Plan summarizes recent SIP updates and their status for each of the nonattainment areas in the State. It also provides information on the ARB s statewide strategies for mobile sources and consumer products. An outline of current and future activities to update the SIP for the new federal 8-hour and PM2.5 standards is available. Lastly, the regional SIPs are a good summary resource of recent significant district actions taken to address sources under local authority.

Toxic Air Contaminant Control Program

The ARBs statewide comprehensive air toxics program was established in the early 1980's. The Toxic Air Contaminant Identification and Control Act (AB 1807, Tanner 1983) created California's program to reduce exposure to air toxics. The Air Toxics "Hot Spots" Information and Assessment Act (AB 2588, Connelly 1987) supplements the AB 1807 program, by requiring a statewide air toxics inventory, notification of people exposed to a significant health risk, and facility plans to reduce these risks.

Under AB 1807, the ARB is required to use certain criteria in the prioritization for the identification and control of air toxics. In selecting substances for review, the ARB must consider criteria relating to "the risk of harm to public health, amount or potential amount of emissions, manner of, and exposure to, usage of the substance in California, persistence in the atmosphere, and ambient concentrations in the community" [Health and Safety Code section 39666(f)]. AB 1807 also requires the ARB to use available information gathered from the AB 2588 program to include in the prioritization of compounds.

Adopted Airborne Toxic Control Measures A list of the Airborne Toxic Control Measures (ATCMs) adopted by ARB is available. Each ATCM is codified under Title 17 of the California Code of Regulations (17 CCR). A staff contact is provided for each adopted measure, allowing you to obtain a copy of the corresponding staff report or technical support document.
Airborne Toxic Control Measures Under Development. The Rulemaking Activity web page provides information regarding ATCMs under development that are still in the formal rulemaking phase.

Actions to Reduce Motor Vehicle Emissions

ARB is responsible for developing statewide programs and strategies to reduce the emission of smog-forming pollutants and toxics by mobile sources. These include both on and off-road sources such as passenger cars, motorcycles, trucks, buses, heavy-duty construction equipment, recreational vehicles, marine vessels, lawn and garden equipment, and small utility engines. For more information, please click on the two web links provided below, or call toll-free 1‑800‑242‑4450.

Summary of Mobile Source Programs The Mobile Source Program web page provides detailed information on the status of ARB programs to reduce emissions from mobile sources. The information is, summarized by the type of mobile source control program or activity.
Status of Mobile Source RegulationsThe Rulemaking Activity web page provides a summary of mobile source regulations adopted by ARB, or in the formal rulemaking process, to control emissions from motor vehicles.

Cal/EPA Legislatively Mandated Reports