Do you need an APEN or air permit?

Update: Potential air permit and air pollutant emissions reporting fees increase.

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.

First, determine if you need an APEN. Then determine if you need a permit.

Application completeness

Your application will be rejected if:

It is filled out incorrectly.
It is missing information.
It is missing required forms.
It lacks payment for the filing fee.

The Form APCD-100 and all applicable forms on that checklist are required with almost every application. The resubmittal will require a new filing fee.

Visit the Application Rejection Frequently Asked Questions page for more information.

The following application types are exempted from the requirement to submit the Permit Application/Registration Checklist (Form APCD-100):

Air Pollutant Emission Notice (APEN) updates only (no changes to permit).
Renewal of 5-year APEN term.
Update to actual annual emissions, per AQCC Regulation 3, Part A, Section II.C.
APEN exempt sources.
Permit exempt sources.
Administrative permit amendments.
Including but not necessarily limited to name changes, changes in contact information, transfers of ownership, and typographical error corrections.

Required APEN updates

You must update your APEN every five years, or if your actual emissions increased from the levels reported on a previous APEN.

Reporting air emissions and applying for air permits: Step-by-step guidance

To report air emissions and apply for a permit, read the detailed guidance document.

Guidance at-a-glance

Below is a summary of the steps outlined in the detailed guidance document. Refer to the full guidance document for more information.

What are the sources of air pollution? What pollutants are being emitted? What federal requirements apply?

“Criteria pollutants” and “non-criteria pollutants” are regulated.

Criteria pollutants include:

Carbon monoxide.
Nitrogen oxides (NOx).
Sulfur dioxide.
Particulate matter (PM10, PM2.5, total suspended particulates).
Ozone.
Volatile organic compounds (VOCs).
Lead
Fluorides.
Sulfuric acid mist.
Hydrogen sulfide.
Total reduced sulfur.
Reduced sulfur compounds
Municipal waste combustor emissions.

Non-criteria pollutants are called hazardous air pollutants (HAPs) and are found in Air Quality Control Commission Regulation 3 Appendix B.

A full list of the sources that don’t need to submit an APEN is in Regulation 3, Part A.II.D. (APEN-exempt) and the APEN and permitting exemptions web page. If your source type is on these lists, you don’t need to submit an APEN or get a permit.

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.

Guidance for calculating your emissions.

We provide resources such as guidance, tools, and policy memos on our APEN, reporting, and air permitting guidance for small businesses web page. Information is categorized by equipment type or source type to help you calculate your emissions.

You must first determine if your source is located in the ozone nonattainment area. The Denver Metro/North Front Range area (DM/NFR) is considered to be nonattainment for the National Ambient Air Quality Standards (NAAQS) for ozone.

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 the air division’s fact sheet or interactive map. If you are still unsure if your facility is in the nonattainment area, contact the CDPHE Air Pollution Control Division.

If your emission rate is higher than APEN thresholds in the table (and your source does not qualify for an exemption based on something other than emissions), you need to submit an APEN. The uncontrolled actual emissions in a calendar year must be compared to the APEN threshold. Uncontrolled actual emissions do not take into account any pollution control equipment that may exist.

If your emission rate is below APEN thresholds, you don't have to submit anything to the air division. Continue to keep track of your emissions and revisit this page if your emissions go above APEN thresholds.

When considering permit thresholds, all sources of emissions at the same site that are above APEN thresholds for a given pollutant must be added together and then compared to the appropriate permit threshold for the pollutant.

APEN and Permit Reporting Thresholds for Attainment and Nonattainment Areas

	Calendar Year Uncontrolled Actual Emissions
	APEN Thresholds		Permit Thresholds1
Pollutant	Attainment	Nonattainment	Attainment	Nonattainment
VOCs (Volatile Organic Compounds)	2 tons	1 ton	5 tons	2 tons
PM-10	2 tons	---2	5 tons	---2
PM-2.5	2 tons	---2	5 tons	---2
TSPs (Total Suspended Particulates)	2 tons	---2	10 tons	---2
CO (Carbon Monoxide)	2 tons	---2	10 tons	---2
SOx (Sulfur Dioxide)	2 tons	---2	10 tons	---2
NOx (Nitrogen Oxide)	2 tons	1 ton	10 tons	---2
Other Criteria Pollutants3	2 tons	---2	2 tons	---2
Pb (Lead)	100 pounds	---2	200 pounds	---2
HAPs (Hazardous Air Pollutants)	250 pounds	---2	N/A	N/A

1These thresholds are for equipment from the entire facility (total facility uncontrolled actual emissions from all sources above APEN thresholds for this pollutant), and not just one individual piece of equipment.
2 Colorado does not have an existing nonattainment area for this pollutant and utilization of the attainment area thresholds is appropriate.
3 Other criteria pollutants: fluorides, sulfuric acid mist, hydrogen sulfide, total reduced sulfur, reduced sulfur compounds, and municipal waste incinerator emissions.

If you do not need an air permit, complete and submit APEN forms and fees.

If you need an air permit, go to Step 9.

If your source requires an APEN, you might need a permit. Just like with APENs, a source can be exempt from permitting based on:

Type of emissions source.
Amount of annual emissions.

If you have multiple sources at your facility, consult the detailed guidance.

A full list of the sources that don’t need a permit is in Regulation 3, Part B.II.D. If your source type is on this list, you don’t need to get a permit. If your source requires an APEN, you must still submit one. For a list of frequent exemptions, visit the APEN or air permitting exemptions web page.

If your source type is not listed as permit-exempt in Regulation 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 emission 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.