Stationary Source Permitting - Community Questions
The purpose of this webpage is to help the public understand how stationary source air quality permitting is conducted in California relevant to the jurisdiction of the 35 local air districts and the California Air Resources Board (CARB). In September 2021, Environmental Justice representatives from across the state met with CARB to share questions related to the stationary source permitting process. This effort resulted in over 160 unique questions that ranged from requests to provide clear definitions of commonly used terms to clarifying the original intent of complex regulatory programs. In response, CARB and the California Air Pollution Control Officers Association (CAPCOA), which is an association that represents the air districts throughout California, formed a temporary subgroup to develop responses to each question.
We intend to provide answers to the remaining questions provided by community members and will continually add new responses as they are developed. Therefore, this draft webpage will be updated by CARB and CAPCOA over time. This webpage does not, and is not intended to, describe all aspects of air quality regulations and law related to stationary source permitting. This webpage is informational only and does not, and is not intended to, describe interpretations of regulations or law by air districts or CARB that apply to stationary sources.
For more information on this effort, or to submit additional questions, please use our webform.
Filter Q & A Results
Filter By Keyword (filter questions and/or answers that contain your keyword)
Filter By Category (filter questions based on category)
Clear & Expand
AB 617 – Assembly Bill 617 (C. Garcia, 2017)
AC/ATC/PC– Authority to Construct
APCD – Air Pollution Control District
AQIA – Air Quality Impact Assessment
AQMD – Air Quality Management District
ATCM – Airborne Toxic Control Measure
BACT – Best Available Control Technology
BARCT – Best Available Retrofit Control Technology
CAPCOA – California Air Pollution Control Officers Association
CARB – California Air Resources Board
CEQA – California Environmental Quality Act
DAC – Disadvantaged Community
ERC – Emission Reduction Credit
HRA – Health Risk Assessment
LAER – Lowest Achievable Emissions Rate
NESHAP – National Emissions Standards for Hazardous Air Pollutants
NSPS – New Source Performance Standards
NSR – New Source Review
PO/PTO – Permit to Operate
PRA – Public Records Act
PSD – Prevention of Significant Deterioration
RACT – Reasonably Available Control Technology
SIP – State Implementation Plan
TAC – Toxic Air Contaminant
T-BACT – Best Available Control Technology for Toxics
U.S. EPA – United States Environmental Protection AgencyBack to Top
The common types of air quality permits issued for stationary source operations can be issued at the facility or equipment level and include the following:
Authority to Construct (ATC) - These are permits that are issued by air districts to project applicants that allow a permit holder (owner/operator) to build, construct, modify, or relocate equipment. An ATC permit can authorize on-going operations until a permit to operate is issued. (Also referred to as: Pre-construction Permit, Permit to Construct (PC), Authority to Construct (AC))
Permit to Operate (PTO) - These permits are issued by air districts to operators once all ATC permitting requirements are met. (Also referred to as: Permit to Operate (PO), Operational Permit)
Pre-Existing Permits - Some air districts issue special permits to older sources that existed before rules were adopted (Also referred to as: Grandfathered permits, In-house permits, Loss of exemption permits)
Title V Permits - These permits are issued by the air district or U.S. EPA to major source facilities and other federally defined operations1. They are enforceable by the air district, U.S. EPA, and the public via citizen suits and contain conditions to ensure compliance with federal air quality requirements which includes requirements for recordkeeping, monitoring, and reporting. (Also referred to as: Part 70 permits for those Title V permits issued by an air district or Part 71 permits for those Title V permits issued by U.S. EPA).
Legal Citation: 1Title 40 of the Code of Federal Regulations, Chapter 1, Part 70 (Part 70)
Related questions include G6 and D1.Back to Top
As a summary, the air quality agencies identified below are involved in permitting processes related to criteria pollutant control in California:
Thirty-five local air districts are the primary regulators of stationary sources of criteria air pollutants. The air districts are the primary agencies that review and issue air quality permits for stationary sources of air pollution.
The United States Environmental Protection Agency (U.S. EPA) and California Air Resources Board (CARB) are oversight agencies that may be involved in the permitting process related to criteria pollutant control in California.
The United States Environmental Protection Agency (U.S. EPA) sets national ambient air quality standards for mobile and stationary sources of criteria pollutants and oversees state and local air quality efforts to meet those standards. U.S. EPA also reviews and enforces Title V permits, which are operating permits for major sources of a criteria pollutant.
The California Air Resources Board (CARB) is the lead air quality regulatory agency for California. It sets state ambient air quality standards and coordinates and provides oversight for meeting federal ambient air quality standards, including by working closely with air districts to develop State Implementation Plans.
However, state environmental air quality laws are not applicable on tribal fee land. Tribal Governments regulate emissions sources on tribal fee land and depending on their specific situation, will implement Clean Air Act programs or partner with US EPA to enforce the Clean Air Act.
In addition to the agencies listed above, many federal, state, and local government agencies have some level of involvement in the air quality permitting process in California, either directly or during the California Environmental Quality Act (CEQA) process, including, but not limited to: City or county land use agencies, California Energy Commission, California Department of Toxic Substances Control, State Lands Commission, State and Regional Water Quality Boards, and the California Coastal Commission.
Related questions include A1 and A13.Back to Top
CARB has developed webpages intended to provide important information to the public on the permitting process. The Stationary Source Permitting webpage contains important links to pages that cover permitting topics such as NSR, BACT Program, Title V, and air district rules.
Related questions include A5 and D2.Back to Top
There is no centralized database that contains all the air permits across the State. Instead, individual air districts have determined how to display permits on their individual webpages. Some air districts post permits online during the public comment period as part of their public notification process. Other air districts, including South Coast AQMD, Santa Barbara County APCD, and Mojave Desert AQMD have online tools that contain facility operating permits. Some of these tools also provide additional information such as engineering evaluations, compliance history, and emissions data.
Mojave Desert AQMD Permit Tool
South Coast AQMD Facility INformation Detail
Santa Barbara County APCD Permitted Facilities Map
Additionally, U.S. EPA launched two public dashboards that contain electronic permits received from air districts in Region 9 to enhance data transparency, which is aligned with some of California’s obligations under AB 617:
U.S. EPA Title V Permit Dashboard
In September 2022, the Governor signed AB 1749 which will require air districts with a population of more than 1 million residents to post their air permits online.
Related questions include A5.Back to Top
Air districts may issue several different types of air permits. The organization of these permits may differ by permit type and often look different across the air districts.
In general, all permits may contain the following:
- Facility Name
- Facility Location
- Facility ID
- Permit Number
- Permit Type (Facility or Equipment)
- Equipment Description (e.g., Emissions Unit and Controls)
- Permit Conditions (e.g., Emissions Limits, Monitoring Requirements, Recordkeeping Requirements, Source Testing Requirements, etc.)
- Applicable Rules
Additional information may be included in individual air permits, including a staff evaluation report that describes the staff analyses and bases for the permit action. For more information, contact your local air district.
Related questions include G2, G6 and D2.Back to Top
The graphic below provides a general overview of the permitting process statewide. For more specific information on the permitting process in your area, please contact your air district.
Related questions include G2.Back to Top
Permits issued in accordance with Title V of the Clean Air Act are submitted to U.S. EPA for review prior to issuance1. Other types of permits and associated technical support documentation are occasionally sent to CARB, U.S. EPA, or other air districts to review based on individual air district rules and policies. Any comments provided are considered by the permitting agencies.
Legal Citation: 140 Code of Federal Regulations §70.8
Related questions include D2.Back to Top
Air district permits for a facility or its equipment generally are valid for a period of time and “expire” after that period ends. Some permits are only needed for a short time, such as ATC permits, and do not require renewal or reissuance once they expire. Other PTO and Title V permits are required for operation and thus need to be renewed, reissued, or extended consistent with an air district’s processes before the permits expire in order for the facility or equipment to operate lawfully. If equipment that requires a permit is built or operated without a valid permit, the owner or operator is subject to air district compliance and enforcement action, which may include penalties for each day of operation1.
Legal Citation: 1California Health & Safety Code Division 26, Part 4, Chapter 4.
Related questions include G4.Back to Top
The timelines for permit renewals vary between air districts and may be required annually or up to every 5 years.
When a permit is considered expired varies by permit type:
ATC permits are valid for a specific length of time and may expire unless a facility has commenced construction prior to the date listed or obtained an extension from the air district. In some cases, an ATC permit may be extended if the operator meets additional requirements as specified in the regulations.
PTO permits may have an expiration date listed and renewals are issued if permit conditions are met, and renewal fees are paid.1,2
Title V permits have an expiration date listed and are required to be renewed at least once every five (5) years. The operator must apply for a permit renewal at least six (6) months (but no sooner than 18 months) prior to expiration. If an operator submits a timely and complete application and the expiration date passes, the existing permit is considered an "extended permit" and the existing permit remains enforceable until the permitting agency issues the renewal. In most cases when these permits appear to be expired, they are actually extended. The requirements associated with Title V permit renewals, including the application period and public process, are defined by federal law. Categories: General
Legal Citation: 1California Health & Safety Code § 42301(e); 2California Health and Safety Code section 42301, subdivision (b)
Related questions include G3.Back to Top
Individual air district permitting rules specify criteria, including emissions thresholds and/or equipment capacity, for when air permits are required for stationary sources to operate. All stationary sources that trigger air permitting are required to apply for and obtain a valid permit to operate. Facilities that are found to be operating without permits must apply for the required permits, install control equipment (if required), and pay fines and/or permit fees prior to receiving a permit to operate. When a stationary source fails to comply with air district rules or operates without a permit when one is required, enforcement action is taken. If the facility disregards the enforcement action and continues to operate out of compliance, an air district may seek an order of abatement or court injunction to force the facility to shut-down operations until compliance is achieved.
Related questions include G3, G4 and D17.Back to Top
Emissions increases associated with new facilities, modified facilities and relocations are subject to local, state, and federal requirements (implemented largely by air districts). For air district requirements, potential emissions increases are calculated, and each air district has different thresholds, based on attainment status and state and federal NSR requirements, for applying new or modified requirements for these sources including allowable offsets, stringency of emission control technologies (e.g., BACT), modeling (e.g., HRA, AQIA), and public notification.
Related questions include G6.Back to Top
For all New Source Review (NSR) permitting actions, increases in emissions are calculated and if those projected emissions increases exceed specified thresholds, then the offset process works as described below:
Related questions include G1 and O2.Back to Top
Offsets are required when there is an emission increase at a facility that exceeds thresholds identified in individual air district rules and regulations. These thresholds vary depending on the level of nonattainment with ambient air quality standards for regional criteria pollutants. This ensures that regions with greater air quality challenges are required to offset emissions from projects at lower thresholds.
Related questions include O1, G2 and R5.Back to Top
For sources that trigger New Source Review (NSR) (new, modified with increase, relocated): The air district requires the installation of the appropriate level of control technology, which is often Best Available Control Technology (BACT) or Lowest Achievable Emissions Rate (LAER). Under this scenario, there are no alternatives to direct control, though, if certain thresholds are exceeded, offsets may also be required to mitigate impacts above and beyond the installation of controls.
For existing sources (that do not trigger NSR): Existing sources are subject to District prohibitory rules (e.g., air district internal combustion engine rules) that can require retrofit and control of existing equipment. In some situations, rules that require the retrofit of existing equipment may not be cost-effective for all facilities to install additional controls. In these situations, some air districts have rules that allow for alternative compliance pathways including mitigation.
Related questions include R4 and R5.Back to Top
The federal Title V permitting program has requirements for enhanced public participation including permit public noticing and public hearings in some cases. For other types of permits, public notice requirements are set by individual air district rules and policies. For proposed permitting actions that trigger notice requirements, air districts post in local newspapers, online, or have other public notification systems. For example, many of the air districts have email notification systems that will notify you of proposed permitting actions at a specific facility, in a region, or across the entire air district.
Related questions include A5, D2 and N3.Back to Top
For new or modified projects proposed near schools, State law1 requires notification of the parents of children at the school, as well as other nearby schools, and all addresses within 1,000 feet of the source. There is a 30-day public comment period that follows the distribution of the public notice, and the air districts are required to respond to all written comments prior to taking final action on the permit. Air districts may, at their discretion, hold public meeting to inform the public of the permitting project.
Legal Citation: 1The federal Title V permitting program has requirements for enhanced public participation including permit public noticing and public hearings in some cases. For other types of permits, public notice requirements are set by individual air district rules and policies. For proposed permitting actions that trigger notice requirements, air districts post in local newspapers, online, or have other public notification systems. For example, many of the air districts have email notification systems that will notify you of proposed permitting actions at a specific facility, in a region, or across the entire air district. CaliforniaHealth & Safety Code § 42301.6
Related questions include A4, A5 and D2.Back to Top
Community members can be involved in the permitting process by providing public comments to air districts on proposed permitting actions or through the California Environmental Quality Act (CEQA) process. In recent years, improvements have been made to local, state, and federal legislation to ensure that public comments are addressed prior to issuing an operational permit. For example, in January 2020 U.S. EPA amended their Title V Petition Provisions rule to require permitting authorities to respond in writing to significant comments received during the public comment period and to provide that response to U.S. EPA. Additionally, over the past several years, CARB and the air districts have created additional opportunities to engage, listen, and respond to public needs, including through the Community Air Protection Program (Assembly Bill 617, C. Garcia, 2017).
Related questions include A4, A5 and D2.Back to Top
Whenever a proposed permitting action triggers public notice, air districts will provide instructions on how to submit public comment. Generally, these instructions include the time period when comments are accepted, physical mailing address, email address, and contact information for a staff member that can assist the public with any questions. The public can submit a request to the air district for the permit application documents to learn more about proposed project and the air district’s review. Outside of the public comment period the public can also to share their feedback multiple ways. For example, the public can send letters or emails to air district staff or share their feedback at public meetings held by the air district such as workshops or at the air district’s Governing Board meetings.
Related questions include A4 and D2.Back to Top
In communities selected by the CARB Board to develop Community Emissions Reduction Programs, air districts develop the programs that contain strategies that have been developed or informed by community steering committees. The AB 617 statute requires that Community Emissions Reduction Programs cause emissions reductions in the selected community. If the emissions reduction plans include strategies to reduce emissions from stationary sources by requiring add-on controls or process changes, those sources would have to go through the permitting process prior to implementing changes to ensure their effectiveness and enforceability. If the strategy is not associated with permitted stationary sources, such as grants for mobile source emissions, it would be implemented through other air district or CARB programs, not through the permitting process.
Related questions include D8.Back to Top
In response to community advocates and Assembly Bill (AB) 617, many air districts have expanded their community outreach and engagement efforts to enhance public transparency and improve programs to address public concerns. The intent of statute is clear – to reduce emissions of toxic air contaminants and criteria air pollutants in communities affected by cumulative exposure burdens. Yet, AB 617 does not explicitly require air districts to make specific changes to their existing permitting programs. To further reduce emissions from stationary sources, air districts are evaluating opportunities to enhance existing programs in response to public feedback. One example is that the Bay Area Air Quality Management District amended its permitting rules on December 15, 2021, to address localized health impacts in overburdened communities.
Related questions include J2 and J3.Back to Top
To date, none of the approved community emissions reduction programs have contained additional permitting restrictions.
Assembly Bill (AB) 617 does not explicitly require additional permitting restrictions in disadvantaged communities. Permitting is determined based on current air district rules and regulations. However, air districts and the community emission reduction program steering committees consider all potential strategies (including those related to permitting) for potential emissions and exposure reductions. Changes to the air permitting requirements would require amendments to an air district’s permitting rules. The rule amendment process is subject to state and federal laws and it involves many steps which can take multiple years to complete. Additionally, changes in permitting typically would only affect new permits or modified permits with emissions increases.
Related questions include J1, J2 and J4.Back to Top
Existing air district, state, and federal law define permitting requirements for stationary sources are based on regional attainment status with ambient air quality standards, not localized impacts. Air districts issue pre-construction and operational permits if the project meets the requirements in all local, state, and federal air quality laws and regulations.
Related questions include J1, J3 and A1.Back to Top
A number of air pollutants, emitted from a variety of sources, impact the health of Californians everyday. Ground level ozone, particulate matter, and air toxic emissions adversely affect the health and welfare of many California communities, especially children, elderly, people with compromised health, and minority and socio-economically disadvantaged populations. The severity of air pollution in a community is influenced by a variety of factors, including direct emissions from sources in the community, and indirect impacts of emissions transported from outside the community. Air districts and CARB have several technical resources and tools that community members can use to confirm known issues, identify new ones, and prioritize pollutants of concern for emission reduction strategies. Some of these resources include measured air pollutant concentrations from air quality monitors, reported emissions of criteria air pollutants and air toxics from permitted facilities, regional or local-scale emission inventories of criteria air pollutants and air toxics, regional air quality plans, and air quality and health risk assessments. CARB and air districts want to work with community members and local community-based organizations to better understand and characterize air pollution concerns in their community and identify and prioritize solutions.
Note: Air district websites also provide valuable information on permitted facilities, emissions, monitoring, rules and regulations, planning documents and technical reports. Please visit your air district’s website for more information.
Basic Information on Air Pollutants:
- Common Air Pollutants
- Research on Health Effects of Air Pollution: CARB's Health Effects Webpage and U.S. EPA's Health Effects Webpage
- Office of Environmental Health Hazard Assessment (OEHHA) CalEnviroScreen is a screening tool to help identify communities disproportionately burdened by multiple sources of pollution and with population characteristics that make them more sensitive to pollution.
- CARB's Ambient Air Quality Standards Designation Tool provides information on state and federal ambient air quality standards for criteria pollutants.
Emission Inventory Tools and Methods:
- Facility Search Tool allows querying of air district reported facility level criteria pollutant and air toxic emissions at the county, city, or ZIP code level.
- CARB’s Air Pollution Mapping Tool presents facility-specific emissions of criteria, air toxics and greenhouse gas emissions for large facilities subject to CARB’s Cap and Trade Greenhouse Gas Emissions Mandatory Reporting Regulation. The beta version 3.0 of the tool incorporates a new mobile emissions tab that maps emissions from on-road vehicles such as cars, trucks and buses, and additional capabilities that allow users to view and compare the emission summaries and trends for mobile and stationary sources inside a user-defined geographical area anywhere in the state.
- Emission Inventory webpage provides information and data on regional inventories used in State Implementation Plans (SIP), including historical as well as projections of anticipated future year emissions (CEPAM2019v1.03), and descriptions of stationary, area and mobile source categories and the types of sources that are included in them.
- Area Source Methodologies webpage provides the most recent versions of District and/or CARB methodologies for estimating area source emissions.
- Mobile source emission inventory webpage provides tools and methodologies used to estimate on-road and off-road emissions.
- OEHHA/CARB approved heath values for health risk assessments.
- Speciation profiles webpage provides current particulate matter (PM) and total organic gas (TOG) speciation profiles. Speciation profiles provide estimates of the chemical composition of emissions and are used in the emissions inventory and air quality models. CARB maintains and updates estimates of the chemical composition and size fractions of PM, and the chemical composition and reactive fractions of TOG for a variety of emission source categories.
Air Monitoring Data and Tools:
Community members can use air monitoring data collected from CARB, air district, community efforts to determine what pollutants are measured in and around their area, and understand which pollutants are of concern. Regulatory data are collected at several locations across the State, following specific siting criteria, to determine attainment of federal air quality standards.
- Air Quality and Meteorological Information System (AQMIS) provides access to preliminary real-time monitoring data and official historical data.
- Aerometric Data Analysis and Management (ADAM) tool provides official regulatory data and statistics for many criteria air pollutants and air toxics by individual monitoring location as well as at different geographic scales (statewide, air basin, county).
- AQView tool provides access to community air monitoring data from AB 617 air monitoring sites. The tool is currently under development and will have visualization capabilities.
Relevant Plans and Reports:
- CARB’s AB 617 Community Recommendation Staff Reports: Every year as part of CARB’s recommendation for the next set of AB 617 community selection, CARB publishes a staff report that includes an air quality burden assessment for each of the recommended communities. The assessment includes an initial assessment of air monitoring data in and around the community as well as a preliminary community-scale emission inventory.
- State Implementation Plan webpage links to air district and CARB documents on the regional air quality plans. These documents provide a comprehensive look at the regional emission issues and present emission inventory and air quality modeling results.
- Air District AB 2588 Annual Reports: Under state law, air districts prepare and publish the AB 2588 annual report that describes ongoing efforts to regulate and reduce air toxic emissions in their jurisdiction.
Related questions include D2 and D4.Back to Top
CARB’s air pollution mapping tool can be used to identify facility locations, industry type, and pollutants emitted. However, copies of the permits are needed to determine equipment-level information including the types of equipment used, pollutants emitted, and the emission control technology installed. Some air districts post operating permits online; however, any permit can be obtained from an air district by contacting them and requesting copies. Additionally, some air districts include various tools on their websites that provide access facility permit, location, and compliance information. For example South Coast AQMD’s Facility INformation Detail (FIND) tool provides such information, including a filterable, interactive map of facilities.
Related questions include J7 and D2.Back to Top
Yes. Both ATC and PTO permits are public documents. To request these documents, you should contact the air district where the project is to be located for instructions. You may be required to submit a Public Records Act (PRA) request for such documents. Other associated technical support documents, including engineering evaluations, are used by air districts to evaluate the impacts of facilities. It is important to note that some of the permitting documents may contain confidential business information (i.e., “Trade Secrets”), which is not considered a public record under state law and therefore must be redacted prior to making the documents available to the public.
Related questions include E1, E3 and D2.Back to Top
Facilities may be subject to certain rules depending on the type of equipment installed and/or processes occurring at a stationary source. Air districts issue facility-level or equipment-level permits. Both types of permits contain conditions, including emissions limits, that the operator is required to comply with for each piece of equipment. The conditions are developed based on federal, state, and local rules which are cited in each permit. Some air district permits contain a list of local, state, and federal rules and regulations that apply to the equipment subject to the permit. The best way to determine which rules apply to a specific facility is to contact the air district and request their assistance in identifying applicable rules and regulations that reduce harmful emissions from the permitted equipment at a facility. If the facility has a Title V permit, the permit will contain a list of all the applicable air quality rules and regulations.
If a permit is not yet issued, the Air District Rules Tool can be used to identify NSR rules (use the rule type filter and select NSR). NSR rules apply to all new and modified sources based on their emission increases, in addition to industry specific control rules, and general control requirements, such as visible emissions.
Related questions include D2.Back to Top
Air district permits should be referenced to determine the pollution controls installed on a specific piece of equipment. Contact the air district to obtain a copy of the current permit(s) that list out the specific equipment and associated control technology required at that facility. CARB’s Technology Clearinghouse summarizes the types of technology that can be used to control emissions from specific class or categories of sources.
Related questions include D2 and D4.Back to Top
Yes. CARB’s air pollution mapping tool contains filters that allow users to download emissions summaries for stationary source facilities in California.
Use the filters on the left-hand side of the tool (below) to select specific facilities of interest, industry types or region then refine your selection by adding emissions years and pollutants (filter shown in blue circle on the left). Once you have filtered your data, select the “data” tab at the top of the screen, followed by “get data” to download the data to a csv. file (as shown in red circles).
It is important to note that emissions calculation methodologies used to estimate the emissions summaries can change over time. Year-to-year changes in emissions at stationary sources may not necessarily reflect actual increases or decreases in emissions.
Related questions include D4 and J7.Back to Top
Permitting and permit evaluations are performed on an equipment-by-equipment basis. When evaluating air quality permits for modifications to an existing facility the cumulative emissions from all equipment and criteria pollutant emission sources that already exist at that facility are considered along with the newly permitted equipment. Previously permitted toxic emission sources that are related to the permit project may be considered in the health risk assessments as well.
Related questions include G6, G10 and G11.Back to Top
The US EPA and California set Ambient Air Quality Standard (AAQS) for criteria pollutants. If a permit application has emissions that exceed air district thresholds, the district requires air dispersion modeling to determine the impacts and add those impacts to measured background concentrations to ensure that the permit application will not cause or contribute to an exceedance of a standard.
Related questions include G11, J1 and J4.Back to Top
For air quality permits issued by the air districts, health risk impacts are calculated for each permitted unit at the time of permitting and the cumulative impacts of all emission sources at a single facility are assessed every four years through the AB 2588 Toxic Hot Spots Program. The cumulative air pollution impacts of air toxic emissions from multiple facilities are not evaluated and there are currently no guidelines for conducting that type of cumulative air pollution impacts analysis.
With the passage of Assembly Bill (AB) 617, new focus has been placed on cumulative impacts analysis as a method to increase understanding of how multiple air pollution sources impact a particular community. CARB and the air districts are working to determine how to evaluate cumulative air pollution impacts.
Related questions include G10, J1, N8 and T2.Back to Top
The California Environmental Quality Act (CEQA) may be triggered when there is a discretionary action being undertaken by a lead agency (e.g., city, county, etc.). CEQA requires state and local government agencies to inform decision makers and the public about the potential environmental impacts of proposed projects, and to reduce those environmental impacts to the extent feasible. The lead agency is responsible for identifying a project’s significant effects on the environment, including effects on air quality, and identifying mitigation measures to avoid or reduce the severity of identified significant impacts. The CEQA review is also a public review and engagement process and typically begins before an application for an air permit is submitted to the air district. The CEQA and permitting processes may occur concurrently, but in many cases air districts cannot issue an authority to construct permit until the CEQA review process has been completed by the lead agency.
The CEQA process can substantially influence the features of the final project, as there is a lot of discretion in the types of mitigation measures that can be required, including, but not limited to, requirements for the use of zero emissions technologies in disadvantaged communities. Once the CEQA document is certified and/or adopted and the project is approved by the lead agency, the air district may proceed with issuance of a permit if the permit meets all federal, state, and local air quality requirements and if there is no basis for the denial of the permit. Any permit issued by the air district must conform with a CEQA document adopted by a lead agency.
Related questions include G6, N9 and A15.Back to Top
Air quality agencies (i.e., local air districts, CARB, and U.S. EPA) often provide information and comments regarding air quality impacts to local lead agencies that are considering proposed land use projects and analyzing their potential significant environmental impacts under the California Environmental Quality Act (CEQA). The lead agency responsible for overseeing the preparation of the required CEQA analysis is commonly the city or county where the proposed project is located.
Air quality agencies may occasionally take on the lead agency role, but they are typically responsible or commenting agencies as specified by statute and in the state CEQA Guidelines adopted by the Governor’s Office of Planning and Research (OPR). An air quality agency serves as a responsible agency when it has discretionary approval power over a portion of a project such as a permit but does not have the principal discretionary authority to approve the entire project. A responsible agency provides comments on the aspects of a project that falls within its jurisdiction to approve or are within the agency’s area of expertise; for example, an air district would be a responsible agency for a project where an air permit is required. An air quality agency serves as a commenting agency when it does not serve as a lead nor responsible agency and has concerns about potential air quality impacts from a project. Air quality agencies can provide input regarding air quality impacts of a project and can recommend mitigation measures to reduce air quality impacts.
Similarly, local and regional plans and individual project decisions can impact community-scale exposure. CARB may review and provide comments on proposed CEQA plans and projects to give input to other government agencies in an effort to improve air quality and public health. Ultimately, the land use agencies make the final decision about whether to approve a project at its particular location. If the project triggers the need for air quality permits, air districts do not issue those permits until after the lead agency has made a final land use decision and completed their CEQA review.
Air quality agencies can, but do not typically challenge the land use agency’s decision in court. However, the Attorney General has the authority to enforce CEQA compliance where necessary. In some cases, the Attorney General has submitted comments as part of the CEQA process or filed litigation. Settlement agreements can result in a variety of actions, such as additional mitigation measures or local land use ordinances.
Here are a few resources to provide more information on the CEQA process:
- Office of Planning and Research’s CEQA Webpage
- Bay Area Air Quality Management District’s CEQA Guidelines
- San Joaquin Valley Air Pollution Control District’s CEQA Webpage
- Santa Barbara County Air Pollution Control District’s CEQA Webpage
- South Coast Air Quality Management Districts’ CEQA Webpage
- Attorney General CEQA Settlements
Related questions include A15, A1 and N8.Back to Top
Land use decisions and approvals are made by the city or county where the project is located. Air quality agencies (i.e., local air districts, CARB, and U.S. EPA) can potentially influence land use decisions through the California Environmental Quality Act (CEQA) process. Air quality agencies are typically considered responsible agencies or commenting agencies under CEQA and provide review and recommendations to lead agencies on issues within the air quality agency’s area of expertise (i.e., air quality) or permitting authority. If a city or county is the lead agency, it may contact an air quality agency district, as CEQA requires lead agencies to consult with responsible agencies when preparing CEQA analysis for the purpose of soliciting comments on the project’s potential CEQA impacts. Some air quality agencies monitor OPR’s online CEQA State Clearinghouse to identify projects that may warrant review and comments based on a variety of factors, such as proximity to disadvantaged communities, sensitive receptors, or other local emissions sources. Local air districts may also publish CEQA guidelines, thresholds of significance, tools, and methodologies to help guide lead agencies prepare air quality and greenhouse gas emissions CEQA analyses within the local air district jurisdiction.
Related questions include J4, N8 and N9.Back to Top
There is no specific requirement for land use agencies to evaluate potential emissions impacts of existing emissions sources to future residents of new housing projects; however, air districts will provide feedback to land use planning agencies when requested to do so. Air districts may also provide comments on the environmental analysis of low-income housing projects. Similarly, the California Environmental Quality Act (CEQA) typically requires an evaluation of the environmental impacts of a project on the environment (e.g., impact of project emissions on surrounding sensitive receptors) and not necessarily the impacts of the environment on the project.
Per the requirements of Senate Bill 1000, the air district is also providing information, recommendations, and technical tools to assist cities and counties in incorporating “best practices” for environmental justice policies into their General Planning processes around air quality and related community health impact considerations. For example, Bay Area Air Quality Management District has created the Planning Healthy Places guidance document for local governments and developers to address and minimize local air pollution issues during the development process. CARB also has a resource that contains strategies to reduce air pollution exposure near high volume roadways. For more information on potential emissions impacts on proposed housing projects, contact your local air district.
Related questions include N9, A20 and D15.Back to Top
For potential homeowners:
When purchasing a home, the previous homeowner is required to disclose any known substances, material or products that may be an environmental hazard such as, but not limited to, asbestos, formaldehyde, radon gas, lead-based paint, fuel or contaminated soil or water on the subject property.
If the property owner is unaware of any environmental hazards, then the potential homeowner can use existing resources (listed below) to evaluate potential risks, including requesting information on nearby sources of air pollution from the local air district through the public records request process.
For existing homeowners:
Assembly Bill (AB) 2588 (Connelly), the Air Toxics "Hot Spots" Information and Assessment Act, requires facilities found to have a significant risk from their emissions to notify all exposed persons. Once risk assessments (see Risk Assessment) are reviewed by the Office of Environmental Health Hazard Assessment (OEHHA) and approved by the air district, all exposed persons must be notified of the risk assessment results if the district determines that there is a potentially significant health risk associated with emissions from the facility. Each air district is responsible for establishing the notification threshold at which facilities are required to notify all exposed persons with either a letter to individual neighbors, or with a newspaper notification. Some air districts also require the facility to post information about the facility risk at the local library.
The California Environmental Quality Act (CEQA) generally does not require a lead agency to provide notice to residents or property owners if a project will potentially emit toxic air contaminants. Generally, notice is provided to all those who requested notice and posted in certain places, including on the agency’s website, in a local newspaper of general circulation, and direct mail to those property owners and residents of contiguous property. In limited circumstances, such as where a new facility will be constructed, property owners within ¼ of a mile of the project will receive a direct mailing notice that an environmental analysis will be performed.
To learn more about potential exposure risks in your neighborhood the following resources are available:
CARB’s Facility Search Tool provides emissions, prioritization scores, and health risk assessment information for all permitted facilities which are reported to CARB by air districts as part of the AB 2588 Air Toxics Hot Spots program.
CARB’s Air Pollution Mapping Tool can be used to identify locations and emissions releases of the largest stationary sources, including air toxics, using an interactive map.
Bay Area Air Quality Management District’s Permitted Sources Risk and Hazards Map is a tool that can be used to identify estimated risk and hazard impacts from stationary sources.
Santa Barbara County Air Pollution Control District’s Permitted Facilities Map contains a radius tool where users can identify sources nearby.
Physicians for Social Responsibility – Los Angeles (PSR-LA) has developed a 500-foot tool to help residents identify hazards within 500 feet of South and Southeast LA communities.
Additionally, you can Contact your local air district for more information on a specific area or concerns.
Related questions include R5, B5 and N13.Back to Top
Air toxics are compounds in the air that have the potential to harm our health. “Air toxics” is the generic term for these substances, but some agencies have formal definitions of what is considered an air toxic for regulatory purposes. At the federal level, the U.S. EPA identifies specific toxic substances known to cause cancer and other serious impacts as Hazardous Air Pollutants (HAP). In California, CARB has formally identified over 200 Toxic Air Contaminants (TAC) which include all federal HAPs and additional toxic air contaminants. In addition to these, a list of additional air toxics can be found here.
People exposed to air toxics at higher concentrations and over time may have an increased chance of developing cancer or experiencing other serious health effects, such as neurological effects or birth defects. Even at extremely low levels, some chemicals may accumulate in the body causing health conditions long after exposure. Examples of air toxics include hexavalent chromium from metal processing operation, benzene from gas stations, and diesel particulate matter from engines. Your individual risk is determined by several factors, which are described in detail in this Air Toxic Risks Infographic.
Related questions include N2, J7 and T2.Back to Top
As part of the engineering evaluation that is performed when reviewing an air district permit application, district staff evaluate the emissions of air toxics. If the permit application includes a new source or modified source with an increase of air toxics emissions, the evaluation may include a health risk assessment, if triggered, to determine whether the permit application would comply with health risk thresholds. If the health risk exceeds district specified thresholds, the operator must propose project modifications to reduce the health risk, which may include: control equipment, limited operation, increased stack height, etc. If the applicant cannot reduce the health risk below the required threshold risk levels, the air district may deny the application.
Related questions include T1, R1 and J5.Back to Top
Related questions include G6.Back to Top
For criteria air pollutants, State and National Ambient Air Quality Standards are established to protect public health. Based on the regional attainment status, the air districts adopt New Source Review (NSR) and prohibitory plans, rules, and regulations that require the appropriate level of emissions controls to ensure maintenance and/or future attainment of Ambient Air Quality Standards. Air districts developthresholds of significance for regional criteria air pollutants as to not exceed applicableAmbient Air Quality Standards or exposure levels at either the local or regional level. In the California Environmental Quality Act (CEQA) process, the environmental analysis analyzes a project’s criteria pollutant emissions and connects those air quality impacts with likely health consequences in a way that the public can understand. If such an explanation in detail is not feasible, the analysis explains why.
For air toxics, health impacts are directly considered when health risk assessments are performed. Health risk assessments are based on the maximum emissions of toxic air contaminants from a piece of equipment or facility and are based on procedures established by the State’s Office of Environmental Health Hazard Assessment (OEHHA).
Related questions include N5, T2, N4 and J7.Back to Top
A health risk assessment (HRA) is a technical study that evaluates how toxic emissions are released from a facility, how they disperse throughout the community, and the potential for those toxic pollutants to impact human health. A HRA estimates the increase in health risks for people living or working near a facility that may result from exposure to a facility’s emissions of toxic air pollutants. HRAs use a computer program called an air dispersion model to predict how facility emissions move into the surrounding community. For each potential community location, health impacts are calculated using health protective standardized information about breathing rates, daily activities, and pollutant toxicity, which are published by the California Office of Environmental Health Hazard Assessment (OEHHA). The risk assessments are computer calculations that are a tool to identify and reduce possible negative health effects. It’s important to note that numbers provided by HRAs do not refer to actual cases of health problems that will occur from exposure to air toxics. Scientific methods used in HRAs cannot be used to link individual illnesses to chemical exposures.
Related questions include N2, N4, N6 and N7.Back to Top
Health Risk Assessments, or HRAs, are conducted by different agencies to satisfy different requirements.
There are three types of HRAs – 1) New Source Review (NSR) HRAs, 2) AB 2588 HRAs, and 3) California Environmental Quality Act (CEQA) HRAs. In many cases, the air district will perform the HRA in-house, but in some cases the HRA will be performed by the applicant, or a consultant hired by the applicant. In the cases where the HRAs are performed by the applicant or consultant, the air district is responsible for reviewing the HRAs.
NSR HRAs: HRAs are conducted as part of new source review for a new permitted source or a modified source with an increase of air toxic emissions.
AB 2588 HRAs: These HRAs are conducted to satisfy the requirements of the Air Toxics “Hot Spots” Program, which is often referred to by the number of the assembly bill that created it, or AB2588. If a facility’s annual emissions exceed the district’s prioritization threshold for AB2588, then that facility must perform an HRA. This type of HRA is conducted on a facility-wide basis. After air district review, this type of HRA is sent to the California Office of Environmental Health Hazard Assessment (OEHHA).
CEQA HRAs: As commenting or responsible agencies, air districts will review HRAs developed for land use projects. The CEQA HRA can also include other non-stationary sources of air pollution, such as mobile sources and construction activities.
CARB staff conduct HRA’s in support of the rule making process to help quantify the reduction in health risk that would result from enacting the proposed regulation.
CARB staff review the HRA submitted by the applicant, for certain types of projects, to ensure that it is correct and complete. CARB staff may also review a CEQA HRA for certain types of projects.
Land Use Agencies
A lead agency is a public agency with the principal responsibility for carrying out or approving a project subject to CEQA. This role is typically taken on by local land use agencies with general governmental jurisdiction. As the lead agency under CEQA, the land use agency is required to oversee the preparation of the CEQA documents analyzing the environmental impacts of a project. This includes an HRA, if it is required. However, most land use agencies do not have expertise in air quality, so the lead agency and project applicant will often contract with an environmental consulting company to prepare the HRA. Through the CEQA review process, the HRA may be reviewed for accuracy and completeness by other local or state agencies with expertise in air quality, such as air districts and CARB.
Related questions include T2, N5, N6 and N7.Back to Top
There are a number of reasons why a health risk assessment (HRA) may be required.
NSR HRAs: District may require an HRA for some projects during the New Source Review (NSR) permitting process. Each District sets its own policies and thresholds for when an HRA is required for permitting actions. In general, they will consider the magnitude and type of emissions from the proposed project, the duration of the project, and the proximity to the public including sensitive receptors.
AB 2588 HRAs: The Air Toxics "Hot Spots" Information and Assessment Act, or AB 2588, requires air districts to prioritize facilities to determine which facilities must perform a health risk assessment. These facilities, for purposes of risk assessment, are ranked into high, intermediate, and low priority categories. Each district is responsible for establishing the prioritization score threshold at which facilities are required to prepare a health risk assessment. In establishing priorities, the districts are to consider the potency, toxicity, quantity, and volume of hazardous materials released from the facility, the proximity of the facility to potential receptors, and any other factors that the district determines may indicate that the facility may pose a significant risk.
In order to assist the districts with this requirement, the California Air Pollution Control Officers Association (CAPCOA) Toxics Committee, in cooperation with the Office of Environmental Health Hazard Assessment (OEHHA) and the California Air Resources Board (CARB), developed the Air Toxics "Hot Spots" Program, Facility Prioritization Guidelines which were originally adopted in July 1990 and amended in 2016 to incorporate the changes made to the OEHHA risk assessment methodology. The purpose of the guideline is to provide districts with suggested procedures for prioritizing facilities. However, districts may develop and use prioritization methods which differ from the CAPCOA guidelines.
CEQA HRAs: HRAs are performed for projects subject to the California Environmental Quality Act (CEQA) when a lead agency determines that an HRA is necessary. Generally, if an air district determines that they will be requiring an HRA for permitting, or if a project is located near schools or other sensitive receptors, air districts can recommend to the lead agency that an HRA be performed for a proposed project.
Related questions include T2, N4, N5 and N7.Back to Top
A health risk assessment (HRA) must be performed using the methodology developed by the Office of Health Hazard Assessment or OEHHA. Click here for a link to the Air Toxics “Hot Spots” Program Risk Assessment Guidelines.
A high-level overview of the steps used to perform an HRA are as follows:
Calculate the toxic air contaminant emissions from the proposed project.
Conduct air dispersion modeling using the information about the emissions sources to determine the area impacted by the emissions and the concentration of the emissions within that impacted area at receptor locations modeled. The air dispersion model typically used is AERMOD, which is the US EPA’s preferred air dispersion model.
Combine the total concentration information from step 2 with information about the toxicity of each air toxic to determine the total cancer, non-cancer chronic, and non-cancer acute health risks at each receptor point. CARB’s HARP2 software can be used to perform this step.
Health risk values are then compared to thresholds set by each air district to determine if the project causes a significant health risk.
Related questions include T2, N4, N5 and N6.Back to Top
When an Agency determines there are no significant health impacts this means that the calculated risk is below health protective thresholds or that nearby receptors (e.g., residences, businesses, workers, structures, etc.) are not impacted.
Emissions of the air toxics are evaluated, and health risks are estimated in a health risk assessment, and if the estimated health risks are above health protective thresholds, the air district will not issue the permit unless modifications are made to lower the health risks below the threshold. If the health risks are below all applicable health protective thresholds, the permit can be issued.
Related questions include T2, N4, N6 and N7.Back to Top
There are many different federal, state, and air district rules and regulations that specify when facilities must use air pollution controls to reduce emissions of air toxics. U.S. EPA’s air toxics regulations are outlined in federal NESHAPS which can either be regulated as major or area sources. In most cases, air districts implement and enforce these federal regulations. CARB develops statewide ATCMs that require best available control technology for air toxics and must also consider cost and health risk in developing and adopting these ATCMs. Air districts can implement the ATCM or adopt a more stringent rule. Air districts also implement California’s AB 2588 Air Toxics “Hot Spots” Program, which requires facilities to report their air toxics emissions, quantify health risk to the public from those emissions, and reduce their health risk below the air district’s risk reduction thresholds. Exceeding these thresholds can result in the need for additional controls. Facilities may also be subject to air district air toxics rules which may have further emission limitations for air toxics and air toxics controls specifications.
Related questions include T1, T2 and J5.Back to Top
Similar in concept to best available control technology (BACT), T-BACT (or Toxics BACT) requirements ensure that new or modified sources that emit air toxics are well controlled. The T-BACT requirements for each air district’s program are defined in air district rules based on local health risk assessment thresholds.
For example, in South Coast Air Quality Management District (SCAQMD) Rule 1401(d), T-BACT must be applied on a permit to construct a new, relocated, or modified permit unit if the emissions of any toxic air contaminant listed in Table I of Rule 1401 will result in a cumulative increase in maximum individual cancer risk (MICR) greater than one in a million.
Related questions include R1, T2, B2 and A6.Back to Top
Prior to issuing a permit for construction, federal and state law requires air districts to conduct new source review (NSR). The specific NSR requirements for each air district vary based on the area’s ambient air quality attainment status. One of the elements of every NSR program is BACT. The intent of BACT is to ensure the cleanest technology available is installed for new, modified, or relocated sources that exceed certain emissions thresholds. The BACT control level is defined based on regional ambient air quality attainment status and specific additional requirements outlined in air district rules and policies.
For more information on the BACT please visit CARB’s BACT program page.
Related questions include B2, B5, R5 and D6.Back to Top
Related questions include B1, B5, R5 and D6.Back to Top
Air districts generally use two types of documents to assist in the identification of BACT - determinations and guidelines. It is important to note that not all air districts have BACT determinations or guidelines. Unless an air district has a unique source, many smaller air districts rely upon the BACT determinations and guidelines from other air districts and the BACT clearinghouse of other agencies such as CARB or U.S. EPA to ensure their permits comply with air district BACT requirements.
BACT determinations contain emissions limits that a specific piece of equipment (or process) has been required to meet within the air district. Typically, air districts develop BACT determinations to document the installation of technology cleaner than previously permitted that has achieved its required effectiveness. This information allows permit engineers to confirm that an emissions limit has been achieved in practice, which is a critical step for ensuring that the most stringent emissions controls are required (and sets a new floor for required emissions limits for sources that trigger Lowest Achievable Emissions Rate, or LAER). For this reason, CARB's BACT database only contains determinations that have been verified by operational or pre-construction permits.
BACT guidelines provide an overview of the limits that may be required when a source type is permitted. Guidelines are helpful for assisting permit engineers and source engineers initially determine the limits and associated technologies that may constitute BACT. The information contained in guidelines may come from multiple sources including permits from within and outside of the air district or state, regulations, or as a result of a literary review. Guidelines may also contain information on conventional and alternative equipment that has been determined to be technologically feasible but is not yet required as BACT. Air districts in California commonly use guidelines when determining emissions limits for minor sources.
Related questions include B4, B5, N12 and D6.Back to Top
When air districts issue permits for new, modified or relocated emissions sources they must first determine if BACT is triggered, and if so, the level of control required. Air districts’ individual New Source Review (NSR) permitting rules and policies define their process for identifying BACT. The most common process air districts use to identify BACT includes the following steps:
Step 1: Identify all potential control technologies
Step 2: Eliminate technically infeasible options
Step 3: Rank remaining control technologies by control effectiveness
Step 4: If most effective controls are not achieved in practice, perform cost-effectiveness analysis and document results
Step 5: Select BACT
To support this process, CARB is required to maintain a Technology Clearinghouse that contains BACT and T-BACT determinations. These determinations are used by air districts when writing or updating NSR permits. This system also helps air districts determine which technologies have been achieved in practice for a class and category of source, which is the minimum level of control required when a source triggers BACT.
Related questions include B3, B5, D6 and A6.Back to Top
There are three levels of control that may apply to new and modified sources with an emissions increase in California:
- Federal BACT: Required on major new or modified sources in areas that are meeting national ambient air quality standards (i.e., attainment areas).
- Federal Lowest Achievable Emissions Rate (LAER): Required on major new or modified sources in areas that are not meeting national ambient air quality standards (i.e., non-attainment areas).
- California BACT: Allows air districts to require more stringent controls beyond LAER on sources if technologically feasible and cost effective.
The stringency of each level of control required varies, based on a region's air pollution challenges.
Further information on how each level of control is defined and determined in California can be found on the BACT definitions page.
Related questions include R5, B5 and N13.Back to Top
Cost thresholds are used differently based on the level of BACT stringency triggered.
- Federal BACT is an emission limitation (including opacity limits) based on the maximum degree of reduction which is achievable for each pollutant, taking into account energy, environmental, and economic impacts, and other costs1. Many air districts have established BACT cost-effectiveness thresholds in their rules or policies that determine when the cost of controls are considered economically infeasible.
- Federal Lowest Achievable Emissions Rate (LAER) is defined as the most stringent emissions limitation contained in the SIP for any State, or the most stringent emissions limitation achieved in practice by a class or category of source, whichever is most stringent2. In 1989 U.S. EPA provided guidance on the economic feasibility of LAER stating that costs should not be considered unless a given control strategy is so great that a new major source could not be built or operated. The guidance also clarifies that “if some other plant in the same (or comparable) industry uses that control technology, then such use constitutes de facto evidence that the economic cost to the industry of that technology control is not prohibitive.”
- CA BACT allows air districts to require more stringent controls beyond LAER on sources if technologically feasible and cost effective. This level of BACT allows air districts to require new technologies that are technically feasible but not yet determined to be achieved in practice.
Legal Citations:1Title 42 Code of Federal Regulations § 7479(3), 2Title 42 Code of Federal Regulations § 7501(a)(3)
Related questions include C1, G5 and A8.Back to Top
The Technology Clearinghouse is an online database that contains current regulatory emissions limits and associated control technologies in the form of rules, regulations, and BACT determinations for sources statewide. Additionally, U.S. EPA maintains a federal RACT, BACT, LAER Clearinghouse (RBLC) that contains emissions limits and associated control technologies for emissions sources across the country. While these systems can help users understand the types of technologies available and potentially required today, they do not provide information on the actual technologies installed on equipment statewide. Air district permits contain information on the equipment installed at each facility, permitted emissions limits, and required control technology. The stringency of control required in individual permits may vary statewide based on considerations such as air district attainment status, cost-effectiveness, and timing.
Related questions include D2, A16 and D9.Back to Top
Historically, CARB has developed guidance for consideration throughout the State such as suggested control measures for existing sources and permitting guidance for new sources. More recently, Assembly Bill (AB) 617 requires CARB to establish and maintain a statewide clearinghouse that identifies the best technologies for reducing emissions, namely BACT, best available retrofit control technologies (BARCT), and best available control technologies for toxics (T-BACT)1. The statute also requires that air districts use this statewide clearinghouse, also referred to as the Technology Clearinghouse, when making BACT determinations and updating BACT guidelines.
Air district determinations of what is considered BACT are not consistent across the state. While the Technology Clearinghouse can help users identify the cleanest technologies available for a particular class or category of source, state and federal law contains requirements for specific levels of control based on regional attainment status. Because of this, a small source in an extreme non-attainment area may be required to install more stringent controls than a larger source in an attainment area. Additionally, the air districts have further defined emissions trigger levels and cost-effectiveness thresholds in their individual BACT policies, which help to determine the technologies that are ultimately required. To provide more transparency on this process, CARB and air districts have been working together to try and further explain air district BACT programs and are evaluating opportunities to enhance consistency when possible.
Legal Citation: 1California Health & Safety Code § 40920.8
Related questions include A7, A8, A16 and D7.Back to Top
Although BACT and LAER programs are defined by state and federal law many of the underlying terms associated with these programs are not formally defined and are instead defined by air districts in their individual rules and policies. To implement Assembly Bill (AB) 617, CARB and air districts have been working closely together to enhance the transparency of the permitting process, including the creation of new CARB webpages to explain the BACT program and associated definitions.
Related questions include A7, A13, N13 and D1.Back to Top
The Technology Clearinghouse contains emissions limits and associated control technologies identified by air districts as best available control technology (BACT) and best available retrofit control technology (BARCT). It is up to the individual air districts to review this information and determine the appropriate BACT and BARCT standards for their individual circumstances. Historically CARB has developed recommendations for statewide standards for existing sources via suggested control measures, which air districts can voluntarily adopt. Additionally, CARB is working with air districts to determine ways to clearly identify technologies that have been achieved in practice for new, modified, or relocated sources that trigger BACT.
Related questions include A6, A7, A8 and A16.Back to Top
Air districts have historically submitted BACT determinations to CARB, which is subsequently provided to U.S. EPA to satisfy federal requirements to add this information to U.S. EPA’s RACT BACT LAER Clearinghouse (RBLC).
In addition to federal requirements, Assembly Bill (AB) 617 requires1 CARB to “establish and maintain a statewide clearinghouse that identifies the best available control technology and best available retrofit control technology for criteria air pollutants, and related technologies for the control of toxic air contaminants.”
Air districts are subsequently required to “use the information in the statewide clearinghouse established and maintained by the state board [CARB]” when “updating best available control technology [BACT] determinations.” CARB has interpreted this requirement to mean that the air districts must submit BACT determinations and/or any additional information that supports the use of technology that results in emissions limits lower than previously required.
Legal Citation: 1 California Health & Safety Code § 40920.8
Related questions include B3, B4, B5 and D6.Back to Top
When air districts receive a permit application from an operator, they typically begin evaluating potential emissions control options by reviewing technology commercially available today. To support this process, AB 617 requires air districts to consider and use the information in the Technology Clearinghouse established and maintained by CARB when updating BACT determinations1. These BACT determinations help to establish the minimum level of control required for new or modified sources.
Legal Citation: 1California Health & Safety Code § 40920.8(b)Back to Top
CARB is required by statute1to develop and maintain a Technology Clearinghouse that identifies BACT, T-BACT, and BARCT. This system contains information on existing limits required by air districts and a Next Generation Technology module where CARB and air districts work together to identify promising technologies that reduce emissions beyond existing regulatory requirements.
Legal Citation: 1California Health & Safety Code § 40920.8
Related questions include D2, D8, D9 and D10.Back to Top
To support continued advancement of technology, CARB and air districts are working together to build out the Next Generation Technology module of the Technology Clearinghouse which contains alternative technology options that are cleaner than currently required. This module of the system is required by Appendix F of the AB 617 Blueprint and is intended to highlight available and installed technology. The public can use this information to support future state and local regulatory actions or to identify opportunities to utilize available incentive funds.
Related questions include D2, A16, D9 and D10.Back to Top
CARB and air districts will continue to work together to expand the Next Generation Technology module of the Technology Clearinghouse to include alternative and zero emissions technologies for prioritized equipment types. Prior to publishing a new Next Generation Technology tool to identify alternative technologies for a specific type of equipment, CARB and air districts conduct extensive outreach with technology manufacturers, facility operators, and local permitting authorities, to ensure the technologies identified are technically feasible. If the public has an interest in technology available for a source not yet covered in the Technology Clearinghouse that you would like us to prioritize, please email us at TechnologyClearinghouse@arb.ca.gov.
Related questions include D2, D8, A16 and D10.Back to Top
State law1 directs the CARB to implement a program to assist districts to improve the efficiencies in the issuance of permits. Additionally, CARB has broad oversight authority2 over air district permitting and enforcement programs.
Historically CARB and the California Air Pollution Control Officers Association (CAPCOA) have worked together to develop guidance documents to help enhance consistency between air district programs, including the 2001 CAPCOA Best Available Control Technology (BACT) Guidance and the 1990 CARB Cost-Effectiveness Guidance. CARB has also developed suggested control measures, that air districts can electively adopt to control specific equipment addressed in each of these model rules.
Legal Citations: 1 California Health & Safety Code § 39620, 2California Health & Safety Code § 41500
Related questions include A7, A13 and N13.Back to Top
There are various statutory requirements and exemptions depending on the process. Permitting, best available control technology (BACT) determinations, rulemaking, best available retrofit control technology (BARCT) rulemaking, and State Implementation Plan (SIP) attainment may have different requirements. The California Health & Safety Code Division 26 contains these requirements for air districts.
State law1 provides the following guidance surrounding application of cost-effectiveness: "Districts shall also consider the cost-effectiveness of their air quality programs, rules, regulations, and enforcement practices in addition to other relevant factors, and shall strive to achieve the most efficient methods of air pollution control. However, priority shall be placed upon expeditious progress toward the goal of healthful air."
For rulemaking, state law contains the requirements for air district rulemaking cost-effectiveness2,3, and socioeconomic analysis4,5.
Minor Source BACT in South Coast Air Quality Management District (SCAQMD) is required to analyze cost effectiveness6 to ensure minor source BACT determinations are cost effective. It is the only air district in the state that is required by state statute to analyze cost effectiveness for minor source BACT.
Legal Citations: 1California Health & Safety Code § 40910, 2California Health & Safety Code § 40703,3California Health & Safety Code § 40920.6, 4California Health & Safety Code § 40728.5, 5California Health & Safety Code § 40440.8, and 6California Health & Safety Code § 40440.11
Related questions include N13, G5 and A8.Back to Top
Air districts are responsible for developing rules for stationary and area-wide sources that emit criteria pollutants or toxic air contaminants. The air districts’ rule books contain a variety of rule types which can be accessed using the CARB’s Technology Clearinghouse, including the following: Air district administrative rules, general rules, New Source Review (NSR) rules, incentive rules, prohibitory rules, federal rules, state airborne toxic control measures (ATCMs), and transportation control measures.
The air district’s prohibitory rules contain emissions limits that meet a specific stringency level at the time the rule is adopted, that is required based on state, local, and federal rules, and statutes. The following webpages contain more information on rule stringency levels for criteria air pollutants:
Best Available Control Technology (BACT)
Best Available Retrofit Control Technology (BARCT)
Reasonably Achievable Control Technology (RACT)
Related questions include G5, B1, O1 and R7.Back to Top
BARCT is an emissions limit stringency level that is typically required through the rulemaking process. State law1 defines BARCT as “an emissions limitation that is based on the maximum degree of reduction achievable, taking into account environmental, energy, and economic impacts by each class or category of source.”
Legal Citation: 1California Health & Safety Code § 40406
Related questions include R3, R7 and X10.Back to Top
According to the California Supreme Court1, BARCT is technology forcing. The court has held that BARCT is especially rigorous and has a “technology-forcing character” that is “designed to compel the development of new technologies to meet public health goals.”
Legal Citation: 1American Coatings Ass’n v. South Coast Air Quality Dist. (2012) 54 Cal. 4th 446, 465, 466
Related questions include R2, R7 and X10.Back to Top
The Technology Clearinghouse contains an air district rules tool that includes a filter labeled "rule stringency" that can be used to identify the rules air districts have determined to be at BARCT stringency level at the time the rule was adopted.
Related questions include R2, R3 and X10.Back to Top
Related questions include R2, X3 and X6.Back to Top
The bill analysis and other documents associated with legislative proposals often contain descriptions that convey the intent of proposed bills and can help agencies and courts interpret legislation, though these background materials do not create binding interpretations or requirements. The Assembly Bill (AB) 617 Assembly Floor Analysis states the following: “Section 2, working in conjunction with Section 3, which requires ARB to update BARCT standards to guide air districts’ determinations, will result in the installation of available emissions control technologies and equipment upgrades, so that real emissions reductions in nonattainment pollutants will be achieved from the dirtiest units located at industrial sources. These being the same industrial sources that will continue to receive free GHG emissions allowances under the cap-and-trade regulation. The provision is not intended to permit the use of emission reduction credits in lieu of installation of BARCT, including marketable emission reduction credits issued under RECLAIM, which is being phased out by [South Coast Air Quality Management District] SCAQMD.”
Related questions include R2, X8 and X10.Back to Top
Although the term “source” is not explicitly defined in the statute, the term source is often generically used to describe the collective emissions from an individual facility or is used interchangeably with the terms device or unit to describe equipment level emissions. In AB 617 the bill requires consideration of both the broader facility-level emissions with the use of the term “industrial source1” and equipment-level sources with the term “permitted units2.”
Legal Citations: 1California Health & Safety Code § 40920.6 (c)(2), 2California Health & Safety Code § 40920.6 (c)(3)
Related questions include X1, X2 and X3.Back to Top
Industrial sources are defined as sources (e.g., facilities) subject to the Cap-and-Trade Program as of January 1, 20171, that are eligible for free allowance allocation (i.e., excludes energy generating facilities and opt-in covered facilities). Industrial sources subject to the Expedited BARCT statutory requirements are further defined as sources that emit a nonattainment pollutant and that are located in an air districts in nonattainment for one or more air pollutants2. Individual emissions units operating at industrial sources are not subject to Expedited BARCT requirements if they have “implemented BARCTdue to a permit revision or a new permit issuance since 2007.” 3
For more information, please visit CARB’s air pollution mapping tool and select "yes" under the AB 617 Expedited BARCT Facilities filter (shown circled in red below).
Legal Citations: 1California Health & Safety Code § 40920.6 (c)(2); 2California Health & Safety Code § 40920.6 (c)(1); 3California Health & Safety Code § 40920.6 (c)(3).Back to Top
Assembly Bill (AB) 617’s Expedited BARCT requirements refer to “nonattainment” generally; CARB therefore understands them to apply to air districts in nonattainment with either state or federal ambient air quality standards for criteria pollutants1. AB 617 BARCT requirements are triggered when an air district is in nonattainment “for one or more air pollutants” (id.), and CARB therefore understands the statute to require BARCT specifically for those “one or more [criteria] air pollutants” for which the air district is in nonattainment.
Legal Citation: 1California Health & Safety Code § 40920.6(c)
Related questions include X1, X3 and X4.Back to Top
Assembly Bill (AB) 617 Expedited BARCT requirements only apply to “nonattainment” pollutants, which are criteria air pollutants designated by CARB or U.S. EPA under state or federal law1. The direct control of non-attainment pollutants, including VOCs and PM-2.5, may result in co-benefits, including a reduction in toxic air contaminants.
Legal Citation: 1California Health & Safety Code § 40920.6(c)
Related questions include X1, X2 and X4.Back to Top
Assembly Bill (AB) 617 Expedited BARCT requirements contain only one exemption for individual “emissions unit[s]” that have “implemented BARCT in response to a permit revision or new permit issuance since 20071.” Thus, for an entire Cap-and-Trade industrial source to be exempt from the BARCT schedule, all of its emissions units would need to have implemented BARCT due to a new permit or permit revision since 2007 for each non-attainment pollutant. Although this exemption does not explicitly include emissions units that have implemented best available control technology (BACT) since 2007, some districts have determined that their BACT limits are equivalent to BARCT.
Legal Citation: 1California Health & Safety Code § 40920.6(c)(2)
Related questions include X1, X7 and X8.Back to Top
AB 617 is focused on securing “expedited” emission reductions from certain Cap-and-Trade industrial sources and requires the implementation of BARCT at those sources “by the earliest feasible date, but in any event not later than December 31, 2023.”1. Given the purposes of AB 617, its directive language, and legislative history, CARB understands this requirement to mean the full installation of required BARCT controls by December 31, 2023. However, it should be acknowledged that the timelines established in the bill were extremely ambitious and that the expectation to evaluate, propose and adopt rule amendments as appropriate, and install BARCT-level controls on nearly 10,000 emissions units subject to these requirements is a significant undertaking, especially for complex sources.
Legal Citation: 1California Health & Safety Code § 40920.6
Related questions include X1 and X11.Back to Top
The statute does not explicitly define the term “schedule”, but the term generally means a “procedural plan that indicates the time and sequence of each operation.” State law1 already requires air districts to develop “a list of regulatory measures scheduled or tentatively scheduled for consideration during the following year.” Assembly Bill (AB) 617 can be read in concert with this existing requirement to additionally require air districts to outline when BARCT measures, including rules or individual permitting actions, will be considered and/or implemented on an expedited schedule.
Legal Citation: 1California Health & Safety Code § 40923(a)
Related questions include X1, X6 and X10.Back to Top
Generally, air districts have the authority to adopt rules to implement state laws for the use of emission credits, which includes the authority to limit or proscribe uses. However, for Expedited BARCT specifically, CARB views the use of regional offsets to comply with BARCT rules adopted to implement AB 617 as inconsistent with the requirements and intent of AB 617.
Related questions include X1, X4 and X8.Back to Top
Statute requires BARCT-level controls to be installed on permitted units at certain Cap-and-Trade industrial sources that have not “implemented BARCT due to a permit revision or a new permit issuance since 20071.” Emissions units that have not been modified with an increase of emissions for decades thus have not triggered best available control technology (BACT) or New Source Review (NSR) over that same time period, and in some cases, rules may not have been recently amended or adopted addressing these sources. AB 617 requires current BARCT-level controls to be installed on these units if BARCT-level controls are not already permitted and installed.
Legal Citation: 1California Health & Safety Code § 40920.6(c)(2)
Related questions include X1, X4, X6 and X8.Back to Top
Assembly Bill (AB) 617 does not define a specific role for CARB in the implementation of Expedited BARCT beyond the agency’s general oversight powers. CARB has broad, ongoing oversight authority for air district implementation of state air quality laws. To summarize the status of Expedited BARCT implementation, CARB and the air districts maintain an Expedited BARCT webpage that contains air district commitments and anticipated rule adoption dates.
Related questions include X1, A8, A9 and A13.Back to Top
Individuals and communities can participate through public participation and comment during development of air district rules and any permitting activities that are noticed for public comment that relate to Expedited BARCT implementation. Most air districts offer list serve notifications where the public can sign up to be notified about any permitting or rulemaking activities.
In the early stage of Expedited BARCT, each air district implementing the law also held a public meeting prior to adopting their Expedited BARCT schedules before January 1, 2019, to “take into account the local public health and clean air benefits to the surrounding community, the cost-effectiveness of each control option", and the "air quality and attainment benefits of each control option” as required by the statute1. The schedules developed through this public process are available on CARB’s Expedited BARCT webpage, which includes links to each air district’s Expedited BARCT staff reports (click the district name for more information).
Legal Citation: 1California Health & Safety Code §40920.6(d)
Related questions include X1.Back to Top
Due to the transient nature of many air pollution complaints, complaints related to stationary sources should be promptly filed with the air district to facilitate the investigation of the matter. Air pollution complaints related to stationary sources should be filed with the air district online or by calling the air district’s compliant line. For more information, please visit the air district’s website. CARB also receives complaints related to stationary sources of air pollution. When CARB receives a complaint, staff forward that complaint to the air district for investigation and requests a summary of that investigation. Complaints can be submitted to CARB online or by calling (800) 952-5588.
Related questions include E3 and E5.Back to Top
There is no centralized database that contains all the statewide air district compliance data. For Title V facilities, the U.S. EPA maintains their Enforcement and Compliance History Online tool that provides information on violations related to air, water, biosolids, industrial stormwater, hazardous waste, and drinking water. Stationary source inspections conducted by CARB will be included in CARB’s Enforcement Data Visualization System. For information on inspections conducted and violations identified by the air district, please contact the air districts directly.
You may contact the air district to request such documents. Please note that for active investigations, some information cannot legally be shared. In South Coast AQMD, enforcement history for each facility can be accessed through the South Coast AQMD Facility INformation Detail (FIND) web application.
Related questions include E1, E5 and D2.Back to Top
Stationary sources’ compliance with permit conditions are continually assessed by air district inspectors. To request compliance history on a specific facility of interest, contact your local air district. Some air districts maintain lists of stationary sources that have recently been out of compliance and publish this information online. For example, South Coast Air Quality Management District (SCAQMD) makes all compliance information for a facility in its jurisdiction available on its Facility Information Detail web application.
Related questions include G3, G4 and G9.Back to Top
Air districts determine the inspection frequency based on several criteria, including the facility’s compliance history and relative risk that a facility may cause if it is found operating out of compliance. Inspections can also result from air quality complaints. In most cases, air districts seek to inspect all permitted equipment at facilities annually. For larger sources, this may mean that an air district inspector is at the facility multiple times per year. For example, Bay Area AQMD has compliance and enforcement staff that are dedicated to performing inspections fulltime at the Bay Area refineries. In some cases, sources may be inspected less frequently than once per year. Sources that might be inspected less than once per year include, but are not limited to remote unmanned back-up generators, such as those found at remotely located cellular towers or smaller sources with low emission potential.
Related questions include E3 and E5.Back to Top
Air districts aim to perform unannounced inspections in the vast majority of cases. Although rare, in some situations, facilities may receive notice before inspections are performed. For example, remote or unmanned facilities might require coordination in advance so that access to equipment or process areas can be granted, such as a backup generator serving a cellular telephone tower. In these instances, the inspector may still make initial contact through an unannounced inspection, perform as much as the inspection as possible, and schedule the remainder of the inspection for such areas. Should an inspection need to be scheduled, it is scheduled as soon as possible following the initial outreach, often within a few hours of being notified.
Related questions include E2, E8 and E9.Back to Top
The outcomes of inspections are documented in inspection reports. If any compliance issues are identified, the inspector’s observations are documented in a notice to comply or a notice of violation. Inspection reports can be obtained through a Public Records Request. For more information on a specific facility of interest, contact your local air district.
Related questions include E2, E3 and E9.Back to Top
In general, inspection reports, notices to comply, and notices of violation are a public record but may contain some confidential (redacted) information or may not be available while an active investigation is ongoing. If a member of the public is interested in viewing these documents, you can submit a public records request to your local air district. In many cases, air districts may also include a monthly notice of violation report to their Board of Directors.
South Coast Air Quality Management District (SCAQMD) makes all records of Notices to Comply an Notices of Violation for a facility available to the public and they can be accessed through their Facility Information Detail, or FIND, web application.
Related questions include E2, E3 and E8.Back to Top
State law vests air districts with the primary authority to regulate stationary sources of air pollution. Air districts may also implement federal Clean Air Act requirements, if they are delegated to do so by the U.S. EPA. As such, air districts regularly inspect stationary sources to ensure that the sources are operating in compliance with air pollution control rules, regulations, and permit conditions. CARB has broad air district oversight1 to ensure that air district programs are implemented effectively. In exercising this oversight, CARB may participate in inspections with air districts to ensure facilities are operating in compliance and that air district enforcement programs effectively support California’s clean air goals. Similarly, U.S. EPA has authority to inspect stationary sources subject to federal requirements, including facilities with Title V permits, for compliance and to address violations directly. U.S. EPA maintains a public tool, ICIS-AIR, which contains compliance and inspection data on major stationary sources of air pollution.
Legal Citation: 1California Health & Safety Code § 41500
Related questions include A9, A10 and A13.Back to Top
CARB staff prioritizes its stationary source activities in a number of ways. During air district program audits, CARB staff inspects a variety of industry types to evaluate how effective the air district programs are in ensuring compliance with local, state, and federal rules and regulations. CARB staff also conducts inspections of facilities in disadvantaged communities that bear the disproportionate burden from environmental pollution. Additionally, CARB and air district staff may conduct inspections of facilities emitting air toxics and facilities that are of interest to the public in coordination with other local, state, and federal agencies. These stationary source inspections include evaluating compliance at facilities that have been the subject of local air pollution complaints and reviewing corrective actions taken to ensure those facilities return and remain in compliance. When conducting stationary source inspections, CARB staff works closely with air district enforcement staff, since air districts have primary authority over stationary sources of air pollution.
Related questions include A2 and A10.Back to Top
State law vests air districts with the primary authority to regulate stationary sources of air pollution. However, CARB has broad oversight authority1 over air district permitting and enforcement programs. CARB is responsible to ensure that air district programs are implemented effectively. CARB performs audits of air district programs at the direction of the Board or when legislation specifically requires CARB to conduct such an audit. To support the effectiveness of stationary source enforcement programs at the state and local levels, CARB also provides online training to air districts and responds to air district support requests.
Legal Citation: 1 California Health & Safety Code § 41500
Related questions include A2, A8 and A10.Back to Top
State law vests air districts with the primary authority to regulate stationary sources of air pollution. CARB has broad oversight authority over air districts to ensure that air district programs are developed and implemented effectively to achieve state ambient air quality standards1. To that end, CARB is charged with reviewing air districts’ attainment plans, rules and regulations, and enforcement practices. Comprehensive air district program audits are also a way that CARB exercises this authority. Other ways include targeted joint inspections with air district staff and records evaluations – including records maintained by regulated facilities and records maintained by air districts documenting their activities. When concerns are identified, CARB works with the air district to develop a plan to address those concerns. In the case of comprehensive program audits, this work may involve public meetings during both the planning stages and as a report-back to the community. For Title V and Major New Source Review (NSR) permit actions, U.S. EPA is involved in the oversight and review as required in the air district’s regulations.
Legal Citation: 1 California Health & Safety Code § 41500
Related questions include A13, A14 and A15.Back to Top