Department of
Environmental Quality

DEQ is the state agency delegated by the federal government to issue air quality permits in Idaho. Permits are required by the federal Clean Air Act and set the conditions under which facilities that generate air pollution may operate. The purpose of permits is to ensure compliance with all state and federal air pollution control rules, which are designed to protect public health and the environment.

Any business or industry (source) in Idaho that emits, or has the potential to emit, pollutants into the air is required to have an air pollution control permit from DEQ. Permits are issued when new sources begin operation and when existing sources modify their facilities.

Permit Application Process

Read these documents first to gain an understanding of the air quality permitting process:

• Applicant and DEQ Responsibilities
• Standard Process Pre-application Meeting Agenda
• 15-Day Process Pre-application Meeting Agenda
• Emissions Data Hierarchy Guidance

Types of Permits

DEQ's Air Quality Division issues several different types of permits based on the emissions from the facility and/or emitting source. Permits require sources to comply with all health- and technology-based standards established by EPA and the Rules for Control of Air Pollution in Idaho. If an applicant demonstrates compliance with all applicable federal and state air pollution laws and regulations, DEQ is required by law to issue an air permit.

The permit and accompanying statement of basis include detailed information on the type(s) of pollutants released, how much may be released, how the facility will comply with the air pollution control rules, and how the pollutants will be monitored. Violation of the permit provisions can result in enforcement action.

The following four types of permits are issued: permit to construct (PTC), Tier I (Title V) operating permit, Tier II operating permit, and permit by rule (PBR).

Permit to Construct

An air quality PTC is required prior to construction or modification of stationary sources, such as buildings, structures, and other installations that emit, or may emit, pollutants into the air. A PTC is also required for certain portable equipment such as generators, crushing equipment, asphalt plants, and concrete batch plants. General permits to construct may be available for some portable facilities. Learn more.

• General Permit to Construct for Automotive Coating Operations
• General Permit to Construct for Concrete Batch Plants
• Hot-Mix Asphalt Plants
• Permit to Construct Exemptions

Permit by Rule

A PBR is a streamlined registration process that enables qualified applicants to bypass the need to obtain a PTC or Tier II operating permit before beginning operation. Currently, the opportunity to obtain a PBR is available to nonmetallic mineral processing plants (portable rock crushing facilities) and certain dairies. In addition, under the crop residue burning program, growers must obtain approval from DEQ before burning by registering for a Permit-by-Rule at least 30 days in advance of a proposed burn date. PBRs for other industries are being considered. Learn more.

• Permit by Rule for Dairies
• Permit by Rule for Rock Crushers

Tier I Air Quality Operating Permit

A Tier I operating permit (also known as a Title V operating permit) is required by the federal Clean Air Act for major sources. Major sources are sources that emit, or may emit, 100 or more tons of any regulated air pollutant per year, 10 or more tons per year of any one hazardous air pollutant (HAP), or 25 or more tons per year of any combination of hazardous air pollutants. Learn more.

Tier II Air Quality Operating Permit

Certain facilities that emit air pollution in Idaho may choose to limit production and/or hours of operation, thus lowering their potential to emit pollutants below Tier I permit thresholds and qualifying them for a Tier II operating permit. In other cases, DEQ may require certain sources of air pollution to obtain Tier II permits. The fees for Tier II permits are lower and the reporting requirements less complex than those required for Tier I operating permits. Learn more.

Air Quality Permitting Forms & Checklists

Find helpful checklists and required forms for air quality permits here.

Air Quality Emission Inventory Requirements & Forms

Applicants for air quality permits must submit emission inventories based on the type of project being proposed and the type of permit required. Learn more.

Air Quality Dispersion Modeling

Air quality dispersion modeling is used to estimate concentrations of pollutants that new (or existing) emissions sources may emit. Air modeling is required by the state of Idaho to demonstrate compliance with the National Ambient Air Quality Standards (NAAQS), toxic air pollutant (TAP) standards, and Prevention of Significant Deterioration (PSD) increments. Learn more.