CEQA  / Air Permitting

Air Permitting

Projects which include stationary source equipment such as boilers, heaters, gas turbines, internal combustion engines, paint booths, and/or manufacturing processes, must obtain air permits as well as undergo environmental review under the California Environmental Quality Act (CEQA). Although the air permit generally cannot be issued by the air district or other air permitting authority until the CEQA approval is obtained, the air permit application process is best undertaken concurrent with – but separate from – the CEQA analysis.

The project description and emission calculations used in the CEQA analysis are normally used as the starting point for the air permit application to ensure consistency between the efforts. However, there are practical differences between CEQA analyses and permitting processes that can eventually lead to divergence in the project description and hence, different emission estimates for the two regulatory processes. Thoughtful planning and execution of the parallel efforts is needed to ensure that the differences are recognized, while ensuring that permits reflect a consistent set of assumptions and operating constraints – as well as ensuring that the CEQA analysis has analyzed all of the potential impacts.

For projects which comprise stationary sources of air contaminants, permitting tasks can include:

  • Permit to Construct applications;
    • Emissions source characterization and emissions calculations;
    • Regulatory and rule applicability analysis, including calculation of permit fees;
    • Best Available Control Technology (BACT) evaluation;
    • Offset requirement determination and Emission Reduction Credit (ERC) acquisition;
    • Localized Significance Thresholds (LST) analysis;
    • Air Quality Impact Analysis (AQIAs);
    • Health Risk Assessments (HRAs);
  • Permit to Operate (PTO) applications and renewals;
  • Regional Clean Air Incentives Market (RECLAIM) permitting and reporting;
  • Clean Air Act Title V Operating Permit applications and renewals;
  • Acid Rain Program permitting and compliance;
  • New Source Performance Standards (NSPS) compliance; and
  • National Emission Standards for Hazardous Air Pollutants (NESHAPs) compliance.

Yorke Engineering, LLC (Yorke) can provide the full range of air permitting services, see Air Quality Services on our website.

New Source Review

New Source Review (NSR) is a preconstruction permitting program required under both federal and state statutes for new and modified sources of certain pollutant emissions in amounts defined in each air district. NSR applies to both individual pieces of equipment or processes, i.e., “permit units”, and entire facilities. Two of the primary requirements that must be addressed during NSR permitting are BACT and Offsets, which are addressed in detail below. In addition, prior to permit issuance, large facilities are required to give public notice and conduct dispersion modeling analysis to determine whether downwind impacts would cause violations of ambient air quality standards. Additional information on emissions calculations, AQIA, and HRAs that are needed for both CEQA and air permitting can be found on this site at Emissions Calculations, Air Quality Impact Analyses, and Health Risk Assessment.

Best Available Control Technology

Pursuant to NSR, most new sources that require an air permit are required to install Best Available Control Technology. BACT means the most stringent emission limitation or control technique which:

  1. has been achieved in practice for a source category; or
  2. is contained in the state implementation plan (SIP) approved by the EPA for a source category unless it can be demonstrated that a limitation or control technique is not presently achievable; or
  3. is any other emission limitation or control technique which is determined to be technologically feasible and cost effective for a source category.

In California, BACT is the pollution control standard used to determine what air pollution control technology will be used to control a specific pollutant to a specified concentration limit. BACT is typically proposed by the applicant during the permitting phase of a project – nevertheless subject to air district approval prior to permit issuance.

Although BACT is ultimately determined by the air district during NSR, the applicant must identify all applicable emission standards during the CEQA review, including applicable control technology requirements. Use of BACT emissions controls is also generally the minimum requirement for the mitigation of potential air quality impacts under CEQA. Therefore, it is important that the CEQA project description accurately identify the proposed equipment in terms of type, rating, maximum throughput, and potential emissions to determine the appropriate emission standards and control requirements. There may also be ancillary impacts, such as the use of ammonia for the control of NOx emissions, that must also be included in the CEQA analysis. Including BACT as a CEQA mitigation, which will be required for the air permitting, is a good example of why it’s important to conduct these two processes in parallel and maintain consistency.


Facilities in “nonattainment areas” with a net increase in emissions above district-specific thresholds are required to offset the emission increase by the use of ERCs. Nonattainment areas do not meet the federal or California standards for healthy air, and almost the entire state of California is nonattainment of the state and federal standards for ozone and the state standard for respirable particulate matter (PM10). One of the goals of NSR is to ensure that any emission increase of nonattainment pollutants, i.e., typically ozone precursors (NOX and VOC) and PM10, from the operation of any new or modified source does not impede progress in attaining state or federal ambient air quality standards. To accomplish this goal, NSR gives air districts the authority to deny permits unless BACT is implemented and the applicant provides emission offsets to compensate for any emission increases of nonattainment pollutants.

Offsets can be in the form of acquired ERCs or allocations from a community bank or other reserve – subject to availability, conditions, and limitations. Air district NSR regulations provide for the application, eligibility, registration, use and transfer of ERCs. For small or low-emitting facilities and essential public services, some air districts maintain a community bank or reserve that can be used to provide the required offsets. In order to achieve a “net air quality benefit”, NSR requires that offsets be provided in amounts greater than the emissions being generated, typically 10 to 30 percent more than parity. However, for offset allocations from a community bank or priority reserve, parity is typical because allocations are limited and must eventually be re-banked sometime in the future, such as permitting of a significant facility expansion – due to business growth – which would require the acquisition of ERCs on the open market.