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Step-by-Step Guide for Facilities

The Cleaner Air Oregon program regulates toxic air contaminant emissions from industrial facilities by modeling these emissions and assessing the public health risk to the surrounding community. This step-by-step guide includes instructions and recommended procedures for facilities going through the CAO program. A video tutorial is available to provide an overview of the resources and Risk Assessment process.

For public transparency, DEQ publishes the status of a facility's Risk Assessment on the CAO Facility Status map and makes publicly available the Risk Assessment materials for all facilities on the Oregon Records Management Solution.

At any point in the process, you can email the CAO program at cleanerair@deq.oregon.gov or contact your permit writer for assistance.

​If you have not already been in contact with CAO and/or regional permitting staff about your proposed project, DEQ recommends scheduling a pre-application meeting prior to submitting an application. Requests for pre-application meetings can be sent to cleanerair@deq.oregon.gov.

Begin your CAO application by accessing the appropriate submittal form and submitting the required fees through Your DEQ Online

  • New or Reconstructed sources applying for Standard or Simple ACDPs or Title V Permits should submit the “CAO – New/Reconstructed Source Risk Assessment Application", along with the “New Source Consulting Fee"
  • Existing sources that have been called-in to CAO should submit the “CAO – Existing Source Risk Assessment Application", along with the “Existing Source Call-in Fee"
  • Sources that have previously completed a CAO Risk Assessment that are proposing to make a change to their facility that requires reassessing risk or applying for a CAO permit modification should submit the “CAO – Risk Reassessment/Modification Application"

Resources available to assist facilities include:

Additional information can be found on the FAQ page.

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The Emissions Inventory (AQ520) identifies all toxic emission units, process activity levels, toxic air contaminants, appropriate emission factors, material balance estimates, and emissions calculations (including assumptions, references and methodologies). At this stage, DEQ or the facility determines if source testing will be conducted to complete the Emissions Inventory.

Provide the following information when submitting your Emissions Inventory:

  • Required Forms:
  • Detailed Process Flow Diagram that indicates:
    • All material flows (e.g., feedstock, fuel, and waste materials)
    • Operational information (e.g., Batch/Continuous, operating temperatures, startup/shutdowns)
    • Emission release points for all toxic air contaminant emissions – these must correspond to stack and fugitive modeling input parameters
  • Activity by TEU (e.g., actual, requested potential, capacity, maximum daily)
  • Identification of:
    • Toxic Air Contaminants by TEU
    • Control devices and efficiencies by TEU
    • Emission factors by TEU
    • Material balance emission approach by TEU
  • Emission factors with references and/or background data and calculations
  • Documentation for material balance emission estimates (e.g., all Safety Data Sheets)
  • Sufficient documentation to determine if an activity qualifies as an Exempt TEU (see Exempt TEU Reporting).
  • Technical documentation related to air pollution control device operation and efficiency (e.g., manufacturer or source test data)
  • Source testing data (if applicable)
  • All toxic air contaminant emissions from all Aggregated and Significant TEUs

Resources available to assist facilities in the Emissions Inventory process include:  

Additional information, including emission factor resources and source testing can be found on the FAQ page.​

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The modeling protocol specifies the risk assessment level selected, facility and source characteristics, modeling assumptions, and receptor placement. The risk assessment level selected is typically based on the complexity of the facility and the amount of toxic air contaminants released. If conducting a level 1 or level 2 Risk Assessment, the Modeling Protocol will include stack height, building information, and the distance to residential, worker, child, and acute exposure locations. For level 3 or level 4 Risk Assessments, some of this information will be included in the Risk Assessment Work Plan (see step 4). A Risk Assessment Work Plan and Modeling Protocol can be submitted as a single document to reduce redundancy.

Resources available to assist facilities include:

    • Dispersion Model Selection (Section 2.5)
    • Project Description (Section 2.1)
    • General Modeling Components including source characterization, downwash considerations (if applicable) and urban/rural designation (Section 2.2)
    • Complex Terrain Considerations (Section 4.3.5)
    • Meteorological Data (Section 2.3)
    • Receptor Placement/Modeling Domain (Section 2.4)
  • Quick Reference Guides

More information can be found on the FAQ page.​

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A Risk Assessment Work Plan is required for a level 3 or a level 4 Risk Assessment. The work plan outlines how exposure locations will be assigned, and how risk will be calculated from modeling results. The work plan and Modeling Protocol can be submitted as a single document to reduce duplication.

Resources available to assist facilities include:

    • Residential
    • Worker
    • Child
    • Acute

​More information can be found on the FAQ page

Risk is calculated following the procedures outlined in the DEQ approved Modeling Protocol and Risk Assessment Work Plan. Please refer to the Health Risk Assessment Recommended Procedures for example risk calculations and information on the following report elements to include.

    • Modeling results by exposure location
    • Risk calculations
    • Reporting risk by Exposure Scenario
    • Reporting risk by target organ (if applicable) (Target Organ Spreadsheet)
    • Comparing calculated risk to RALs ([OAR 340-245-8010] Table 1)
    • Risk Assessment uncertainty analysis

More information can be found on the FAQ page.​

While community engagement may take place throughout the Risk Assessment process, the results of the approved Risk Assessment indicates whether a facility's source risk has exceeded the formal community engagement Risk Action Level [OAR 340-245-8010 Table 1].

If this Risk Action Level is exceeded, the facility must participate in and fund community engagement to inform the public of its potential risk. DEQ will work with the facility to implement community engagement and determine what level and fees are required.

More information can be found on the FAQ page.​

If the results of the approved Risk Assessment indicate risk above the Toxics Best Available Technology (TBACT) or Toxics Lowest Achievable Emission Rate (TLAER) Risk Action Level, for existing or new sources respectively, an analysis of all significant TEUs is required and may lead to the implementation of emission controls – see OAR 340-245-0220 for more details.

If the results of the approved Risk Assessment indicate risk above the Mandatory Risk Reduction level, in addition to TBACT analyses, a risk reduction plan must be approved and implemented. Please note that there are different timelines for chronic or acute risk reductions – see OAR 340-245-0130 for more details. 

More information can be found on the FAQ page.​


A facility may choose to conduct monitoring based on the results of the Risk Assessment. Monitoring data may be used to update the Risk Assessment. For assistance on monitoring, contact cleanerair@deq.oregon.gov or your permit writer.​

More information can be found on the FAQ page.​

​Once DEQ has approved the facility Risk Assessment, the CAO Permit Application Form AQ501 must be submitted with any required additional submittals (e.g., risk reduction plan, ambient monitoring plan) and all applicable fees.

Specific activity fee tables (Activities 4 through 25, as applicable)​

​Once the results of the Risk Assessment are complete, DEQ will develop permit conditions that ensure continued compliance to maintain health protective risk levels - these conditions may vary by facility. Some common permit conditions include limits on emissions, operational parameters, production activities, or fuel/raw material usage. Source testing may also be required to demonstrate compliance with these conditions. CAO does allow for sources to be regulated on risk as well, both cancer and noncancer. In these cases, conditions will be required to demonstrate compliance with modeled risk levels, which may include daily calculations for demonstrating compliance with acute noncancer risk levels. ​