First determine if you need an APEN, then determine if you need a permit. The steps to do this are outlined below.
What is an APEN?
An APEN is an Air Pollutant Emission Notice, and is used to:
Report your emissions.
Apply for a permit.
Modify an existing permit.
Your APEN will be rejected if it is filled out incorrectly, is missing information, or lacks payment for the filing fee. The re-submittal will require a new filing fee. See our Application Rejection Frequently Asked Questions page for more information.
You must update your APEN every five years, or if your actual emissions increased from the levels reported on a previous APEN. Our APEN update guidance explains the emission increase amounts that require an APEN update.
Video guide If you're new to this process, watch this video for an introduction to emissions reporting and permit applications.
Steps 1-3: Determine your sources of air pollution, what pollutants are being emitted, and what federal requirements apply.
“Criteria pollutants” and “non-criteria pollutants” are regulated.
Criteria pollutants include: carbon monoxide, nitrogen oxides, sulfur dioxide, PM10, PM2.5, total suspended particulates, ozone, volatile organic compounds, lead, fluorides, sulfuric acid mist, hydrogen sulfide, total reduced sulfur, reduced sulfur compounds, and municipal waste combustor emissions.
Non-criteria pollutants are called hazardous air pollutants (HAPs) and are found in Regulation No. 3 Appendix B.
Step 4: Check if your source is exempt.
A full list of the sources that don’t need to submit an APEN is in Regulation No. 3, Part A.II.D. (APEN-exempt). If your source type is on this list, you don’t need to submit an APEN or get a permit - and you’re done here.
If your source is not on the list, your emissions still may be below the threshold for requiring an APEN. Calculate your emissions to determine if you need to submit an APEN.
We provide resources (including guidance, tools, and policy memos) on our website, categorized by equipment type or source type, to help you calculate your emissions.
Step 6: Determine if you need to submit an APEN based on your emissions.
You must first determine if your source is in the nonattainment area.
Sources in the 8-hour ozone nonattainment area must submit an APEN if VOC and/or NOx emissions are above their nonattainment area thresholds. The nonattainment threshold only applies to VOC and NOx; emissions for all other pollutants should be compared to the attainment threshold. Sources outside the 8-hour ozone nonattainment area should compare emissions to the attainment thresholds.
For more information about the 8-hour ozone nonattainment area, refer to this fact sheet or look at our interactive map. If you are still unsure if your facility is in the nonattainment area, contact us.
If your emission rate is higher than APEN thresholds in the table (and your source isn’t exempt), you need to submit an APEN. The uncontrolled actual emissions in a calendar year must be compared to the APEN threshold.
If your emission rate is below APEN thresholds, you don't have to submit anything to us. Continue to keep track of your emissions and revisit this page if they go above APEN thresholds.
APEN and Permit Reporting Thresholds for Attainment and Nonattainment Areas
A full list of the sources that don’t need a permit is in Regulation No. 3, Part B.II.D. If your source type is on this list, you don’t need to get a permit. But, if your source requires an APEN, you still must submit an APEN. We have listed frequent exemptions on Common APEN or air permit exemptions.
If your source type is not listed as permit-exempt in Regulation No. 3, Part B.II.D., your emissions still may be below the threshold for requiring a permit. The permit emissions thresholds are in the table above. Note that the permit thresholds apply to your entire facility, not just the source you are reporting.
Add the emissions you calculated to the emissions from all other emissions sources at that same facility that require an APEN. If that total meets or exceeds the permit thresholds in the table above, a permit is required.
In Colorado, an air permit is required before you start constructing a new source (except for new oil & gas exploration and production operations, per Regulation No. 3 Part B Section II.D.1.lll) or before you start modifying an existing source.