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Major Businesses

Businesses that emit the largest amounts of air pollutants in our jurisdiction, and other businesses as required by the U.S. Environmental Protection Agency, are regulated under Title V of the federal Clean Air Act. Each Title V business is required to hold an air operating permit.

These comprehensive permits roll together air-related regulations, emission limits, monitoring, record keeping, and reporting requirements into a single document. Like all of our permits, air operating permits help businesses know what they need to do to be in compliance, and they help us and the public hold these businesses accountable.

Emission totals listed for the Title V businesses on the map below are 2022 numbers (including CO2 emissions, which were updated in January 2024).


AOP: air operating permits. They collect existing requirements into one comprehensive document. They do not add requirements or change emission limits. These permits must be renewed every five years.

SOB: statement of basis. A background document that provides a description of the facility and details the conditions and history of the air operating permit.

OAC: order of approval to construct. A construction permit required for projects that would emit pollutants over a certain threshold.

PSD: prevention of significant deterioration. A permit required for new major sources of air pollutants and for major modifications at existing sources of air pollutants. These permits are issued by the Washington Department of Ecology.

CD: consent decree. A legal agreement entered into court record.

BT: means emissions are below the reporting threshold of 10,000 metric tons CO2e

SO2 sulfur dioxide

PM10 particulate matter with a diameter of 10 micrometers or smaller

O3 ozone (in this case, ground level, not stratospheric)

NOx nitrogen oxides

CO2 carbon dioxide

Major Businesses Permit, CD, Orders Permit Status Contact PM10(Tons Per Year) SO2(Tons Per Year) NOx(Tons Per Year) VOC
(Tons Per Year)
(Tons Per Year)
CO2e(Tons Per Year)

Emissions Inventories

What is an Air Operating Permit?

The federal Clean Air Act requires us to renew air operating permits every five years. These comprehensive permits compile air-related regulations and other permits in one place and spell out monitoring, recordkeeping and reporting requirements that businesses must meet. and emissions requirements.

Like all of our permits, air operating permits help businesses know what they need to do to be in compliance, and help us and the public hold them accountable for abiding by the laws, rules, regulations and conditions of their permits. Together, we can be partners in keeping the air clean.

Who needs an air operating permit?
Most businesses don’t need one, but air operating permits are required if a facility has the potential to emit:

  • More than 100 tons per year of any pollutant.
  • More than 10 tons per year of any hazardous air pollutant.
  • More than 25 tons per year of a combination of hazardous air pollutants.
  • A handful of other special cases listed in federal regulations.


Air Operating Permits Do:

  • Collect and record a business’s air quality related requirements in one document.
  • Require the facility to regularly monitor sources of air pollutants, fix leaks and problems promptly, and keep records of what is being done.
  • Require the facility to regularly report any failures to follow the air operating permit terms.
  • Require the facility to report releases of excess emissions.
  • Clarify monitoring, testing, recordkeeping and reporting requirements.
  • Require the facility to certify yearly whether they’ve met the terms of the air operating permit.
  • Make the terms of the air operating permit federally enforceable.

Air Operating Permits Do Not:

  • Increase or decrease emission limits for a facility.
  • Permit or approve new construction.
  • Require environmental impact statements or other reviews under the State Environmental Policy Act

What permits does my major business need?


We work to ensure that major businesses meet the terms of their permits and air quality regulations to protect health and the environment. We use various methods to monitor these facilities’ compliance, including:

  • Monitoring air emissions and processes, and reviewing records and reports submitted by the facility, as required by their permits.
  • Requiring emissions tests.
  • Conducting compliance evaluations.
  • Inspecting facilities.

As the primary air quality agency in our jurisdiction, we strive to meet U.S. Environmental Protection Agency policy for compliance monitoring activities.


Semi-Annual Air Operating Permit Certification Form

Annual Air Operating Permit Compliance Certification Form

initial excess emissions notification (Part 1) form

Excess emission (Part 2) form

EPA Delegation Letter — NESHAP


You can find more information about EPA’s compliance policies and program on the compliance page of EPA’s website.

Our compliance monitoring work provides us with necessary evidence if we need to pursue enforcement against the facilities we regulate. We report our compliance monitoring activities and enforcement actions for major businesses and some non-major businesses to the EPA national database: Enforcement and Compliance History Online (ECHO).

If your air quality is affected at home or work by activities at a major business, you can submit a complaint. (See below.) Because of the number of complaints we receive, we focus our responses on incidents that affect multiple people and properties.

Authorized Representative Form

emissions test summary



EPA Delegation Letter — NSPS


Additional Resources