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Availability of Air Resources (AAR)

The U.S. Environmental Protection Agency (EPA) sets National Ambient Air Quality Standards (NAAQS) to protect public health and welfare. The NAAQS define the maximum acceptable concentrations of certain air pollutants, and thereby the amount of air resources that must be shared by all industrial facilities and other sources of those pollutants.

When the Iowa Department of Natural Resources (DNR) receives an air quality construction permit application, there may be a determination, through computer-aided air dispersion modeling, of the concentration of air pollutants in the ambient air near the facility. This includes any impact the facility may have as well as impacts from nearby facilities. The DNR compares these impacts to the NAAQS to ensure that public health is protected, and summarizes this information in the form of an Availability of Air Resources (AAR) Summary.

When available, an AAR Summary is provided to permit applicants upon permit issuance. The applicant can then use the AAR Summary for planning purposes and to assist in the preparation of future permit applications. AAR Summaries may also be requested using the contact information on this page.

Frequently Asked Questions

How do I request an AAR Summary?

Can I review the information used to produce the AAR Summary?

Is there any cost associated with requesting an AAR Summary?

Can I request an AAR Summary for any location?

How does the AAR assist the DNR in protecting air quality?

I do not have an AAR Summary for my facility. How can we know if our proposed construction project will be required to be modeled?

What sources of air emissions influence the availability of air resources in my area?

How is the amount of available air resources determined?

If the amount of air resources still available in the area is very small, does this mean the area cannot support additional industrial growth?

The total concentration on the AAR Summary exceeds the National Ambient Air Quality Standards (NAAQS). What does this mean?

How can I use the AAR Summary for planning purposes?

What is a Modeling Determination Threshold (MDT)?

What are the National Ambient Air Quality Standards (NAAQS)?

What is a Significant Impact Level (SIL)?

What is a background concentration?

What is ambient air?

Request an AAR Summary
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Alternatively, to request an AAR Summary, contact us directly at: aar@dnr.iowa.gov