Protecting Public Health and the Environment.

Air Quality Emission Inventory Requirements and Forms

Applicants for air quality permits must submit emission inventories to satisfy applicable rules. If emission inventories are not sufficiently documented, the application will be determined incomplete or denied.

Prior to preparing any emission inventory or application materials, it is strongly recommended that the applicant request a meeting or teleconference with DEQ to discuss the applicant’s responsibilities. Contact DEQ’s Air Quality Permit Hotline at 1-877-5PERMIT (1-877-573-7648) to schedule a meeting. Applicants are also encouraged to call the hotline to ask questions as they prepare the application.

Required Types of Emission Inventories

The type of inventory that must be submitted depends on the type of project being proposed and the type of permit required (e.g., new facility or modified facility).

The table below lists the types of emission inventories that must be submitted for each application type and provides links to applicable application templates. Applicants must use the templates, document all calculations, and follow all instructions. 

All emission inventories must be submitted with sufficient documentation that the public and DEQ can verify the validity of the emission estimates. The emission inventories will be subjected to technical review.

Types of Emission Inventories
(Follow link to applicable required application.)

Application Type Facility Wide PTE Inventory Proposed Modification at a Minor Facility Inventory Proposed Modification at a Major Facility Inventory Ambient Impact Assessment Inventory Toxic Air Pollutant Inventory Hazardous Air Pollutant Inventory
New Facility Construction (non-PSD) X     X X X
Proposed Modification to an Existing Minor Facility X X   X X X
Proposed Modification to an Existing Major Facility (non-PSD) X (1)   X X X X
Tier I Operating Permit (New and Renewal) X         X
Tier II Operating Permit (New and Renewal) X     X   X

(1) Under certain circumstances, an existing facility wide PTE inventory may not be required. Contact DEQ to determine if one must be submitted. Under all circumstances, the applicant must prove the existing facility classification.

Emission Inventory Instructions


  1. Use the same emission unit name throughout the application (i.e., in air pollution control equipment forms and for modeling purposes).
  2. On the application, show in detail all calculations used to develop the PTE summary and include the following:
    • Electronic copies of spreadsheets used to estimate emissions. If a spreadsheet is used, submit an electronic copy of spreadsheet (Excel format).
    • Documentation of all calculations conducted by hand (i.e., show all calculations).
    • Clear statements on all assumptions relied upon in estimating emissions.
    • Documentation of the emission factors used to estimate emissions. If the emission factor documentation is readily available to DEQ, such as an EPA AP-42 emission factor, a simple reference to the emission factor suffices. If the emission factor documentation is not readily available to DEQ, the applicant must submit the documentation with the application; ask DEQ if you are uncertain. Documentation may consist of manufacturer guarantees, research conducted by trade organizations, published emission factors, and source test results. If multiple factors are provided for a given operation, note why the factor used is the most representative. Applications without sufficient documentation are incomplete.
    • Copies of manufacturer guarantees upon which emission inventories are based.
    • The best available emission information (see DEQ’s Guidance on Emissions Data Hierarchy).
    • If source tests are used as the basis for emission estimates, the source test report must be submitted. If the source test report is on file with DEQ, provide the date the source test was submitted along with the name of the facility and the emission unit that was tested. Source data from similar emission units may be considered reliable provided it is clearly described why the sources are similar. Similar sources are those that the applicant has shown serve a similar function, use similar raw materials, and have similar processing rates.

Compliance Buffer Component

Air quality permits often include emission rate limits equivalent to estimated emissions included in the application; these are the rates that the applicant has shown demonstrate compliance. If the source exceeds the permitted emission rate limit, it is operating in violation of its permit. In estimating emissions that are used to demonstrate compliance, it may be wise for the facility to request a compliance buffer component of up to 120% of what would have otherwise been estimated (i.e., increase emissions by a factor of 1.2).

If a compliance buffer component is requested, all compliance demonstrations provided by the applicant (i.e., modeling and toxic air pollutant assessments) must include the buffer.