SLO County APCD evaluates new land use development projects that are large or concerning under the California Environmental Quality Act (CEQA) to review the adequacy of the air quality and GHG analysis, the significance of the impacts predicted by the analysis, and the mitigation measures to reduce overall air quality and GHG impacts. Use the tools below to help guide your project through the CEQA process.
All projects, even those not subject to CEQA review, are subject to certain local, state and federal air quality rules and regulations. Review these lists of regulations to determine if they apply to the construction or operational phases of your project.
Land uses that generate air emissions may be subject to APCD permitting requirements. Review this list of land use types to determine if your project is subject to an APCD permit.
Local planning agencies and developers can use these tools to help identify when a project’s air quality and GHG impacts may be insignificant and when APCD review of a project may be required.
The SLO County APCD 2012 CEQA Air Quality Handbook defines the criteria used by the SLO County APCD when evaluating development projects, and includes administrative updates from 2017, 2021/22, and 2023 that provide clarity on certain sections of the handbook and greenhouse gas guidance.
To quantify emission impacts from new land-use developments that exceed the significance levels in the APCD screening tools, APCD recommends using CalEEMod, the California Air Pollution Control Officers’ Association (CAPCOA) web-based land use planning emissions estimator model. The CalEEMod website includes video tutorials on how to run the model, a User Guide and answers to Frequently Asked Questions, and a Contact page for questions and to report bugs or issues with the model. The model includes air quality and GHG mitigation measures that are described in the 2021 CAPCOA Handbook for Analyzing GHG Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity.
1. The Lead Agency, as defined by CEQA, is the public agency that has the primary responsibility for carrying out or approving a project (State CEQA Guidelines Section 15367). To be a CEQA Lead Agency, the public agency must have discretionary authority over the proposed project. The Lead Agency also has the primary responsibility for determining what level of CEQA review is required for a project and for preparing and approving the appropriate document.
As a Lead Agency the SLO County APCD would prepare environmental documents for its own discretionary actions, such as air quality plans and rules, however the SLO County APCD rarely acts as a lead agency.
2. A Responsible Agency under CEQA is a public agency with some discretionary authority over a project or a portion of it, but which has not been designated the Lead Agency (State CEQA Guidelines Section 15381). Because Responsible Agencies will take discretionary actions regarding a project, they are also required to comply with CEQA. For efficiency, CEQA allows Responsible Agencies to rely on a CEQA document prepared by the Lead Agency to meet their CEQA compliance requirements. However, Responsible Agencies must independently review and approve the CEQA document, and not rely automatically on the Lead Agency’s judgments. According to CEQA, a Responsible Agency complies with CEQA: “By considering the EIR or negative declaration prepared by the Lead Agency and by reaching its own conclusions on whether and how to approve the project involved” (State CEQA Guidelines Section 15096(a)).
The SLO County APCD is rarely a Responsible Agency and should seldom be named as a Responsible Agency in CEQA documents because the SLO County APCD does not usually independently review and approve CEQA documents.
3. As a Commenting Agency the SLO County APCD reviews projects that may have air quality impacts and evaluates whether the environmental document provides sufficient information and adequate mitigation to alleviate adverse impacts.
The SLO County APCD usually acts as a Commenting Agency. Comments are submitted to Lead Agencies for their consideration. However, the Lead Agency has the primary responsibility for determining what level of CEQA review is required for a project and for preparing and approving the appropriate document.
Health Risk from Nearby Diesel Trucks and Locomotives
Development adjacent to high-volume roadways and railroads where mobile sources produce diesel particulate matter can present health risks to sensitive receptors. Diesel particulate matter has been classified by the California Air Resource Board’s (CARB) as a toxic air contaminant and a carcinogen. Because of this, the APCD does not support sensitive receptor development near Highway 101 and railroads. Non-sensitive uses and developments such as commercial, parking lots and offices in which occupants are exposed to the health risk for a shorter duration—are better suited to be nearest to Highway 101 and railroads. Health risk decreases with decreased rate of exposure to the toxic source.
Should projects continue, the APCD recommends the following:
Further, residential units sited near pollution sources are generally lower in market value, indicating it is possible residential homes would become affordable to lower-income populations. Low-income community members often face existing health disparities, so siting housing near pollution sources which has a possibility to become affordable may need further consideration (See Page 57 of the CARB’s 2017 Scoping Plan update). To be in alignment with State goals, specifically Assembly Bill 617 which aims to reduce exposure of toxic air contaminants in low-income and disadvantaged communities and protect public health, housing that could become affordable should be sited in a fair environmentally just way meaning “No group of people should bear a disproportionate share of the negative environmental consequences resulting from industrial, governmental and commercial operations or policies” (See EPA webpage – Learn about Environmental Justice). It is important to consider that land use decisions now could create a neighborhood that may bear more of the environmental consequences that come from pollution sources.
Infill within Urban Reserve Lines & Village Reserve Lines
The APCD encourages balance of residential and commercial infill within the existing urban reserve lines (URLs) and village reserve lines (VRLs), as this is consistent with the land use goals and policies of the APCD’s Clean Air Plan. Increasing density can reduce emissions and vehicle miles traveled (VMT) by minimizing the number of trips and travel distances and encourage active transportation. The APCD supports the use of infill development, as it is consistent with SLOCOG’s Regional Transportation Plan and Sustainable Communities Strategy.
Subdivision or Lot Splits Outside Urban & Village Reserve Lines
The APCD is concerned with the continued small lot fracturing of lands outside of the urban and village reserve line which is inconsistent with the land use planning strategies in our Clean Air Plan (CAP). Our CAP calls for these parcels to not be split below 20 acres in size and instead promotes the concept of urban infill by directing growth to areas within the existing URL/VRL boundaries. Mobile sources are the largest contributor to air pollution in our county and rural parcel split projects fosters continued dependency on private auto use as the primary means of accessing essential services and other destinations. For these reasons, the APCD does not support this type of projects.
Support of Mixed-Use Development
The APCD encourages mixed-use development. When people can walk or bike to nearby businesses or parks, traffic is reduced, and we create healthy communities. This is consistent with several of the APCD's land use goals and policies in the Clean Air Plan and helps meet the SB 32 and SB 375 emission reduction targets set by California legislation and the California Air Resources Board.
Incompatible Mix of Land Uses
As individual projects move forward; it is important to keep in mind that some uses may not be compatible and could result in potential nuisance problems (i.e. odors and/or dust). Therefore, it is essential that individual uses be carefully evaluated prior to issuance of a use permit. The following uses could be problematic if residential quarters are included in the same building.
New School Sites
The Public Resources Code Sec. 21151.8 requires any agency preparing an Environmental Impact Report or negative declaration for a proposed school site to consult with the city, county, and the APCD to identify both permitted and non-permitted facilities within one-quarter mile of the proposed school site which may emit hazardous air emissions or handle hazardous materials (e.g., pipelines). Impacts from such a facility may be significant due to increased cancer risk for the affected population, even at a very low level of emissions. If a potentially hazardous facility is within one-quarter mile of the new school site, the APCD may require a risk assessment to determine the potential level of risk associated with that school location. Information on permitted facilities is available by contacting the APCD Engineering & Compliance Division.
School Notification - APCO Required to Notify Nearby Sensitive Receptors
Projects within 1,000 feet from the outer boundary of a school site are subject to California Health & Safety Code 42301.6. The APCO is required by law to take several actions before a final decision is made on the applicant’s permit to construct. These actions include preparing and sending a public notice to parents or guardians of children enrolled in a school that is located within one-quarter mile of the proposed new or modified source and to each address within a radius of 1,000 feet of the source at least 30 days prior to the date final action on the application is to be taken by the officer. To minimize potential delays, prior to the start of the project, please contact the APCD Engineering & Compliance Division for more specific information regarding permitting requirements.
Cannabis Waste Burning is Prohibited
The Federal Government categorizes cannabis as a controlled substance; therefore, crop waste from the agricultural growing of cannabis is not eligible for an APCD burn permit and cannabis waste burning is prohibited. Verified burning of cannabis is subject to enforcement action.
Nuisance – Manufacturing/Processing & Masking/Neutralizing of Cannabis
The following are subject to the APCD’s Nuisance Rule 402 and may result in enforcement action:
Permit – Manufacturing/Processing & Masking/Neutralizing of Cannabis
The following are subject to the APCD’s permitting requirements:
Nuisance Odors from Wineries
Wine production facilities can generate nuisance odors during various steps of the process. Proven methods for handling wastewater discharge and grape skin waste need to be incorporated into the winery practices to reduce off-site odor. Odor complaints could result in a violation of the SLO County APCD Rule 402, Nuisance.
Permit - Agricultural Burning
An APCD Agricultural Burn Permit is required to burn agricultural vegetation on Permissive Burn Days. For more information on agricultural burning, visit the following APCD webpage: slocleanair.org/rules-regulations/agriculture/burning.
Operational Permit Requirements
New wineries or expanding wineries with the capacity of 26,000 gallons (10,000 cases at twelve 750 milliliter bottles per case) year or more require a Permit to Operate for fermentation and storage of wine.
Operational Phase Exceedance From Dirt Roads
Based on the APCD’s spreadsheet modeling for estimating operational dust emissions from daily traffic on unmitigated unpaved roads,driveways, parking areas, and special events, winery projects could exceed the APCD’s daily operational particulate matter (PM10) emissions threshold identified in Table 3-2 of the CEQA Air Quality Handbook (April 2012). The modeling uses the California Air Resources Board’s unpaved road emission factor that is used in their statewide emissions inventory and there is a screening table reference available at: slocleanair.org/rules-regulations/land-use-ceqa.php. If a project will exceed the threshold, the APCD recommends that the project implement the on-site PM10 mitigation measures listed below.
Mitigate the unpaved access roads, driveways, and parking areas by implementing one of the following:
In addition, special events can also trigger a PM10 exceedance. The following special event mitigation shall be implemented for unpaved access roads, driveways, and parking areas on the day(s) of a special event:
If the project’s access involves a city or county owned and maintained road, the applicant shall work with the applicable Public Works Department to ensure that the mitigation follows the agency’s road standards for that section of road. The applicant may propose other measures of equal effectiveness as replacements by contacting the APCD’s Planning Division.
If your project requires an air quality analysis, use this guide to complete the analysis and mitigation for both the construction and operation phases. Quick Guides for Construction and Operational Mitigation Measures can be found in the “Comparing Construction Emissions to Thresholds and Applying Mitigation” section and the “Comparing Operational Emissions to Thresholds and Applying Mitigation” section, respectively.
A Clean Air Plan (CAP) consistency analysis is generally required for a Program Level Environmental Impact Report (EIR), and may be necessary for a Project Level EIR, depending on the project being considered. Examples of projects and programs requiring a consistency analysis include: General Plan Updates and Amendments, Specific Plans, Area Plans, large residential developments and large commercial or industrial developments.
The consistency analysis should evaluate the following questions:
If the answer to all of the above questions is yes, then the proposed project or plan is considered to be consistent with the CAP. If the answer to any one of the questions is no, then the emissions reductions projected in the CAP may not be achieved, which could delay or preclude attainment of the state ozone standard. This would be considered inconsistent with the CAP.
The most recent version of the California Emissions Estimator Model (CalEEMod) should be used to calculate construction emissions. This model contains emission factors for a variety of construction equipment. It will automatically generate default values for various parameters. When modeling project emissions, the user must specify that the project is located in SLO County so that the appropriate default values are used for the modeling. If more detailed information about the construction phase of the project is known, the default values should be modified to more accurately reflect the anticipated emissions from the project. CalEEMod reports submitted as part of a CEQA evaluation need to include the following:
CalEEMod will not automatically calculate import or export off-site hauling trips and associated emissions. If soil or demolition materials will need to be hauled off-site or materials will be imported, cubic yards of material and the number of truck trips will need to be entered into the model. The trip length associated with hauling also needs to be entered into the model along with a detailed explanation of the trip length. Specific truck emission factors for the hauling fleet should be included in the simulation if known. If the specific fleet is unknown at time of modeling, then a defensible worst case set of hauling fleet emission factors shall be used. This hauling component is an important step and is often overlooked resulting in under estimation of emissions.
The grading area and the calculated construction emissions should be compared to SLO County APCD Thresholds of Significance displayed in the table below:
If the above thresholds are exceeded, mitigation measures for construction emissions shall be applied to reduce construction impacts. Please see the SLO County APCD Quick Guide for Construction Mitigation Measures to determine appropriate mitigation for your project.
The most recent version of the California Emissions Estimator Model (CalEEMod) should be used to calculate operational emissions. This software incorporates the most recent vehicle emission factors from the EMFAC model (EMission FACtors) provided by the California Air Resources Board (CARB), and average trip generation factors published by the Institute of Transportation Engineers. This model will automatically generate default values for various parameters. When modeling project emissions, the user must specify that the project is located in SLO County so that the appropriate default values are used for the modeling. If more detailed information about the operational phase of the project is known, the default values should be modified to more accurately reflect the anticipated emissions from the project.
The pending web version of CalEEMod will include 3CE electricity emission factors (lbs of CO2/MWh) associated with the current and future electricity 3CE provides to their customers. The current version of CalEEMod (2020.4.0) does not include these 3CE emission factors and only allows the entry of one emission factor at a time. Therefore, when using the current CalEEMod version to complete an air quality assessment for a project served by 3CE, please use the following carbon dioxide emission factors when defining the project’s “Utility Information” in CalEEMod. Note: These emission factors must be changed to account for project phasing being implemented in different years or when impacts over time are to be evaluated.
|Project Year||3CE Electricity Emission Factors (lbs of CO2/MWh)|
CalEEMod reports submitted as part of a CEQA evaluation need to include the following:
Defaults that may need to be evaluated and modified based on the project location and specifications include:
The calculated operational emissions should be compared to SLO County APCD Thresholds of Significance displayed in the table below:
If the above thresholds are exceeded, mitigation measures for operational emissions should be applied to reduce operational impacts below the significance thresholds listed above. Please see the SLO County APCD Quick Guide for Operational Mitigation Measures to determine appropriate mitigation for your project.
If a project has the potential to cause an odor or other nuisance problem which could impact a considerable number of people, then it may be considered significant. A project may emit a pollutant in concentrations that would not otherwise be significant except as a nuisance. Odor impacts to residential areas and other sensitive receptors warrant the closest scrutiny, but consideration should also be given to other land uses where people may congregate, such as recreational facilities, work sites and commercial areas.
If a project includes any of the proposed operations as detailed in Table 3-3 below and is within the screening level distances stated to sensitive receptors or other areas where people may congregate, the SLO County APCD Compliance Division should be contacted for information regarding potential odor problems. For new odor sources located near existing receptors, the information request and analysis should be based on a review of odor complaints for similar facilities. The Lead Agency should evaluate facilities not included in Table 3-3 or projects separated by greater distances than indicated in Table 3-3 if warranted by local conditions or special circumstances. The list is provided as a guide and, as such, is not all-inclusive.
A CEQA air quality analysis must include an analysis of the project’s greenhouse gas impacts. This guidance for the analysis and mitigation of greenhouse gas impacts should be considered in conjunction with the SLO County APCD 2021 Interim CEQA Greenhouse Gas Guidance document.
The SLO County APCD recommends using the most recent version of the California Emissions Estimator Model (CalEEMod) to calculate greenhouse gas emissions for both construction and operational phases. This software incorporates the most recent vehicle emission factors from the EMFAC model (EMission FACtors) provided by the California Air Resources Board (CARB), and average trip generation factors published by the Institute of Transportation Engineers. For guidance on how to install this model if you have Windows 11, click here.
The SLO County APCD recommends amortizing construction related GHG emissions over the life of the plan/project and adding amortized construction emissions to annual operational emissions for the purpose of providing a mechanism for the plan/project to mitigate these impacts alongside operational impacts. In the 2021 Interim CEQA GHG Guidance document, the SLO County APCD recommends a project lifetime for residential projects of 30 years and establishes a recommended project life for mixed use projects to also be 30 years. This aligns with recommendations from South Coast AQMD, project lives used by Environmental Leadership Land Use Development Projects seeking judicial CEQA streamlining under AB 900, and recommendations by the International Energy Agency in their March 2008 Information Paper entitled, Energy Efficiency Requirements in Building Codes, Energy Efficiency Policies for New Buildings. The SLO County APCD Handbook’s 25-year project life for strictly commercial projects is still recommended by APCD. Lead agencies can consider allowing appropriate alternative project lives.
CalEEMod will automatically generate default values for various parameters. When modeling project emissions, the user must specify that the project is located in SLO County so that the appropriate default values are used for the modeling. If more detailed information about the construction and operational phase of the project is known, the default values should be modified to more accurately reflect the anticipated emissions from the project. CalEEMod reports submitted as part of a CEQA evaluation need to include the following:
Defaults that may need to be evaluated and modified based on the project location and specifications include:
On March 28th, 2012, the SLO County APCD Board adopted the Greenhouse Gas thresholds shown in the table below. The SLO County APCD’s bright-line threshold of 1,150 MT CO2e /yr and the efficiency threshold of 4.9 MT CO2e /yr per service population were applicable to residential and commercial projects. These thresholds were based on a gap analysis and were used in CEQA evaluations for projects to demonstrate their consistency with the state’s 2020 GHG emission reduction goal from the Global Warming Solutions Act (AB 32) and the 2008 California Air Resources Board’s (CARB) Climate Change Scoping Plan. In 2015, the California Supreme Court issued an opinion in the Center for Biological Diversity vs California Department of Fish and Wildlife (Newhall Ranch) which determined that AB 32 based thresholds derived from a gap analysis are invalid for projects with a planning horizon beyond 2020. Since the bright-line and service population GHG thresholds in the SLO County APCD Handbook are AB 32 based and project horizons are now beyond 2020, the SLO County APCD does not recommend the use of these thresholds in CEQA evaluations.
SLO County APCD Greenhouse Gas Thresholds (1)
(1) Supporting substantial evidence for the March 28th, 2012 adoption of these thresholds can be found through the following links: Greenhouse Gas CEQA Thresholds of Significance Initial Study; Greenhouse Gas Emission Thresholds for CEQA Board Staff Report; Board Presentation, March 28, 2012
SLO County APCD staff developed a 2021 Interim CEQA GHG Guidance document to provide administrative clarification on the SLO County APCD Handbook’s thresholds of significance for GHG emissions and to provide information on current trends, best practices, and legislation. The document also provides guidance on analyzing project consistency with GHG reducing plans, policies, or regulations. This document may evolve over time as land use and related GHG reduction strategies, executive orders, legislation, etc. change. It is the responsibility of lead agencies to determine if a project is adequately mitigated or if findings of significant and unavoidable impacts are necessary.