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Air Emissions Inventory (EI) Updates, Tutorials, FAQ and Help

ARS Improvements Webinar

DNR will host a webinar on Thursday, Dec. 8 from 10:00 a.m. – 11:00 a.m. to walk through the system updates and answer questions from attendees prior to emissions inventory reporting season. To attend the ARS Improvements webinar, register Here.


NEW REGULATED POLLUTANT: 1-Bromopropane (1-BP) was added to the hazardous air pollutants listed under section 112(b) of the Clean Air Act, effective Feb. 4, 2022. In addition to the air contaminants listed in Table 2 of s. NR 438.03, Wis. Adm. Code, the department requests reporting of 1-BP emissions to the annual emissions inventory. NOTE: A source’s major source status and applicable requirements may have changed as a result of the addition of 1-BP. For more information, see 1bp-q-and-a-document-final.pdf (
REVISED AIR EMISSIONS INVENTORY REPORTING RULE: The following changes were made to Wisconsin’s air emissions inventory reporting rule (ch. NR 438, Wis. Adm. Code) and are effective starting Aug. 1, 2022:
  • Major sources in nonattainment areas, sources with the potential to emit equal to or greater than 100 tons per year of criteria air pollutants or ammonia, and sources with actual emissions of 0.5 ton per year of lead are now required to report annual emissions of all criteria air pollutants and ammonia, regardless of the reporting thresholds in Table 1 of ch. NR 438. Wis. Adm. Code.
  • An emissions reporting requirement was added to the rule for sources that directly emit fine particulate matter (PM2.5).
  • Particulate reporting requirements were clarified to apply to primary emissions, where primary emissions are directly emitted into the atmosphere, rather than secondary particulates formed through atmospheric chemical reactions.
  • An annual emission inventory may exclude emissions from specific emission units, operations, or activities now listed in ss. NR 438.03(1)(am)(3) and (4), Wis. Adm. Code..
  • State administrative code language was aligned with federal emissions reporting terminology and updated to reflect DNR’s current emissions inventory reporting process.
  • The requirement for the emissions inventory certification signature moves from the owner or operator to the Responsible Official under s. NR 438.03(5)(c), Wis. Adm. Code.
Facilities must comply with the updated rule starting with 2023 air emissions inventory reporting for calendar year 2022 emissions.


The instructions, Credentials and Access, cover how to obtain credentials to access the EI in the Air Reporting System (ARS).

The instructions, EI and EI Certification Basic Steps or Under-Thresholds-Notification (UTN) Basic Steps, cover the basic steps for either submitting and certifying an EI or submitting an Under-Thresholds-Notification (UTN).

Relevant directions for reporting in ARS are also provided throughout ARS.


What changes were made to ARS starting with the 2023 reporting season for calendar year 2022 data?

DNR’s Air Emissions Inventory Updates fact sheet lists recent changes made to ARS.

How does a permitting exemption impact EI?

A permitting exemption has no impact on who should report an EI. The EI requirement is driven by the criteria listed in question Who is required to submit an EI?.

Why is a facility included in the annual EI emailing?

All facilities included in the annual EI correspondence may need to submit an EI or UTN and include:

  • Facilities that had an active permit or permit application during the EI year.
  • Facilities that exceeded reporting thresholds for a pollutant in Chapter NR 438, Wis. Adm. Code, for the previous EI year.
  • Facilities DNR has asked to submit an EI.
Who is required to submit an EI?

(a) Except as provided under s. NR 438.03(1)(am), Wis. Adm. Code, any person owning or operating a facility that emits an air contaminant in quantities above applicable reporting levels, except indirect sources of air pollution, shall annually submit to the DNR an emissions inventory of annual, actual emissions or, for primary particulate matter, primary PM10, primary PM2.5, sulfur dioxide, nitrogen oxides, carbon monoxide and volatile organic compounds, throughput information sufficient for the DNR to calculate its annual, actual emissions. The reportable air contaminants and applicable reporting levels are listed in Table 1 in in ch. NR 438, Wis. Adm. Code.

(af) The owner or operator of a facility shall annually submit to the DNR an emissions inventory for sulfur dioxide, nitrogen oxides, carbon monoxide, volatile organic compounds, primary PM10, primary PM2.5, ammonia, and lead and lead compounds, if the facility meets any of the following:

  1. The facility is a Part 70 major source, as defined under 40 CFR 70.2.
  2. The facility is a nonattainment area major source, as defined under s. NR 408.02(21), Wis. Adm. Code.
  3. The facility has the potential to emit equal to or greater than 100 tons per year of ammonia.
  4. The facility has actual emissions equal to or greater than 0.5 ton per year of lead.
Why is the Submit Data button inactive?

The Submit Data button will only become active after the following steps are completed:

  1. Update Facility Information
  2. Update Contacts
  3. Run Emissions Calculator
  4. Review and respond to QA Flags
  5. Checkboxes for having reviewed Estimated Fees and the Draft Report

Note: The checkboxes will not become active until items 1 through 4 are [COMPLETE].

Who is required to submit a UTN?

Any facility that is below all reporting thresholds in ch. NR 438, Wis. Adm. Code, is not otherwise required to submit an EI (see above FAQ), and has or needs a registration operation permit (ROP) is required to submit a UTN. However, the DNR strongly encourages every facility that is below reporting thresholds, and is not otherwise required to submit an EI, to submit a UTN to confirm that an emissions review has been conducted and contact information is current.

Why is there not a UTN option for this facility in ARS?

A UTN may only be submitted if the source is below all applicable reporting thresholds and is not otherwise required to submit an emissions inventory under ch. NR 438, Wis. Adm. Code.

The following sources must submit an annual emissions inventory of all criteria air pollutants and ammonia, regardless of actual emissions amounts, and are not eligible to submit a UTN:

  • major sources in nonattainment areas
  • sources with the potential to emit equal to or greater than 100 tons per year of criteria air pollutants or ammonia
  • sources with actual emissions of 0.5 ton per year of lead
Why is the Create UTN button inactive in the Air Reporting System (ARS)?

Before an Under-Thresholds-Notification (UTN) can be created, the Update Facility Information and Update Contact Info sections must be completed and saved or marked complete in ARS. For comprehensive directions on how to review/revise contact data, visit the Update Contacts Instructions.

Who is required to certify an EI or submit a UTN?

Every facility that either has or needs a permit or emits NOx or VOC above reporting levels in an ozone nonattainment area must either certify an emissions inventory or, if appropriate, submit a UTN instead of an emissions inventory and certification.

Why are UTNs not certifiable?

UTNs are submitted instead of an EI and EI certification.

Why is the Create Certification button inactive in ARS?

All of the following must be done for the Create Certification button to become active:

  1. the steps indicated on the Submit Data tab (Update Facility Information, Update Contacts, Run Emissions Calculator, Review and respond to QA Flags, ARS Not Already Submitted, and UTN Not Already Submitted) must be marked [COMPLETE]
  2. the two boxes confirming Estimated Fees were viewed and Draft Report reviewed must be checked
  3. the Submit Data button must have been clicked
How is a two-week submittal extension (until March 15 for an EI or UTN) requested?

EI submittal extensions will not be granted via email.

Starting in calendar year 2023 for data year 2022, EI submittal extensions from March 1 to March 15 will not be honored unless they are requested directly in the Air Reporting System (ARS).

To request an extension from March 1 to March 15, follow these steps:

  1. log in to ARS
  2. click Review QA Flags/Draft Report/Estimated Fees/Submit Data/Final Report/Certification/Submit Data Extension Request
  3. click Request Extension
  4. the extension will automatically be approved via email

The EI Certification due date of June 30 may not be extended. UTN submittals do not require separate certification.

How is a device and/or process deleted in ARS?

Devices cannot be deleted, but they can be end-dated. To end-date a device and/or process in ARS, email the facility ID (nine-digit number), device/process ID and end date (the date the device/process should be deleted) to either:

How is a North American Industry Classification System (NAICS) code changed?

To change a NAICS code, email the following information:

  • the facility's identification number (FID)
  • the facility's name
  • the new NAICS code
  • the start date for the new code
How are the air contacts changed (i.e., facility air management contact, facility billing contact, facility air permit contact and responsible corporate official)?

For facility air contact, facility billing contact, and/or facility air permit contact non-submittal roles:

For the responsible corporate official (RCO):

How are the air submittal contacts changed or roles granted (i.e., air compliance submittal, air emission inventory submittal and air permit action submittal)?

See Credentials and Access presentation for detailed directions with screenshots.

How is a control efficiency added and revised in ARS?

See Adding and Revising Controlling Devices and Processes tutorial for detailed directions with screenshots.

Why is a selected device or process missing?

It is likely that an end date was inadvertently added. Email information about the missing device and/or process to either:

Can device or process IDs be changed?

No. Once a device or process is created, its ID is created and cannot be changed. However, a device and/or process can be end-dated and then recreated under another ID if necessary.

How is a facility's name changed?

To change a facility's name, follow the directions on the Notifying the Air Program About Administrative Facility Changes page.

How is a permit revoked?

To revoke an air permit, follow the directions on the Notifying the Air Program About Facility Closings page.

How is a permit application withdrawn?

To withdraw a permit application, the facility’s responsible official (person legally responsible for the operation of the permitted air pollution source [see NR 400.02(136), Wis. Adm. Code]) must submit a written request to DNR by email or letter. This request should be sent to:

    - or -
  • Wisconsin Department of Natural Resources
    Air Program, AM/7
    Attention: Permits
    PO Box 7921
    Madison WI 53707-7921
How does a facility correct a mistake in a submitted EI, either the most recent or from previous years?

Email the DNR the exact corrections that need to be made. One way to do this would be to mark up the draft report or final report and email the redlined version to the appropriate person, which is either:

If it is before March 15 and the edits are for the EI year currently due, the DNR may opt to un-submit the EI and have the facility make the changes instead.

If it is not before March 15 and/or the changes are not for the current EI year, ARS will not be reopened. The DNR will make necessary changes.


For assistance with Switchboard credentials, click on Need Assistance? to request help or Instructions, FAQ and Troubleshooting for detailed instructions and troubleshooting tips.

For EI questions and concerns, contact:

Direct EI related feedback to the Metrics and Emissions Inventory Coordinator: Megan Corrado, 608-405-0327