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How DEQ Protects the Air

DEQ uses a variety of programs and tools to protect public health and Idaho’s air quality. We monitor air quality throughout the year so we can accurately report information to the public and support community efforts to improve air quality. Our technical staff is trained in a variety of disciplines to ensure the data we collect and report are timely and reliable.

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DEQ staff monitor air quality at more than 35 locations across Idaho to help the public make informed decisions about their health. Our locations include one or more of the following: particulate (PM10 and PM2.5) monitors, gas (ozone, carbon monoxide, sulfur dioxide, and nitrogen oxide) monitors, and various meteorological sensors, and the data is used to support multiple programs such as assessing compliance with the NAAQS, supporting our smoke management programs, developing air quality forecasts, and providing current air quality to the public.

An emission inventory (EI) estimates the amount of pollutants emitted within a specified area and time. DEQ uses EIs to identify the primary sources impacting air quality and to ensure that public health is protected.

We use four types of emission inventories:

Permit EI—Developed to support our industrial source permits.

Point Source EI—Compiled annually to estimates emissions for most major sources, calculate Tier I fees, and fulfill annual EPA reporting requirements.

National Emission Inventory (NEI) —Prepared every three years to develop a comprehensive inventory of Idaho emissions, which includes industrial sources, vehicles, residential wood heating, open burning, smaller industrial sources, and natural sources. See EPA for additional information about the NEI.

Area or Project-Specific EI—Prepared when a more detailed emission inventory is needed for specific areas in Idaho to meet EPA nonattainment redesignation requirements, identify the primary emission sources impacting air quality, and verify that areas are still meeting the NAAQS when redesignated to attainment.

Meteorological conditions can cause air pollutant concentrations to increase or decrease by transporting, dispersing, or trapping air pollution near the ground. We use meteorological data to develop daily air quality forecasts for the public and to support the smoke management program.

We use air quality models to help protect Idaho’s air and ensure that areas of the state do not violate the NAAQS. These models incorporate meteorological  data and emission inventories to estimate air quality impacts from a single source or many sources within a large area. We use modeling for SIPs, establishing , background concentrations, and evaluating the effectiveness of the monitoring network.

Permitting Process

We use air quality models during the permitting process to verify emission sources will not cause a NAAQS violation and during the development of implementation plans for nonattainment areas to demonstrate the effectiveness of control strategies.

Background Concentration Tool

Through collaboration with other air quality agencies in the Pacific Northwest and Washington State University, a background concentration tool has been developed that combines modeling and monitoring data to provide information that is used to support the permitting process.

Monitoring Network

Modeling is used to evaluate the effectiveness of our monitoring network. Modeling can help identify whether we need additional monitors or to move an existing monitor or confirm that the current location is adequate.

State Implementation Plan (SIP)

During the development of a SIP or maintenance plan, we use modeling to identify the primary emissions source causing the elevated concentration and then to identify what control measures are needed to improve the air quality and demonstrate that the area will meet the NAAQS. When used to support SIPs we compare the modeling results to the actual monitoring data to help us know how to evaluate the modeling data.

EPA’s Regional Haze Program started in 1999 and requires state and federal agencies to work together to improve visibility in 156 national parks and wilderness areas, which are referred to as Class I areas. This includes popular areas throughout the Northwest such as Craters of the Moon National Monument, Sawtooth Wilderness Area, and the Selway-Bitterroot Wilderness Area, which Idaho is responsible for addressing visibility.

Haze pollution comes from a variety of natural and human-made sources such as windblown dust and smoke from wildfires, smoke from prescribed fire and other open burning, vehicles, electric utilities, industrial fuel burning, and manufacturing operations. Particulate matter pollution is the major cause of reduced visibility in many parts of the United States, including our national parks.

Idaho submitted a regional haze plan to EPA in 2010 that addressed specific emissions from a subset of industrial sources. We are developing the second 10-year regional haze plan that evaluates all current emissions sources and improves Idaho’s Class I areas. DEQ will submit the plan to EPA by July 31, 2021.

Exceptional events are events like smoke from wildfires or dust from extremely high winds that degrade air quality but are not controllable. Other examples of allowable exceptional events are prescribed fires, stratospheric ozone intrusions, and volcanic and seismic activities.

We continually evaluate air quality monitoring data to determine if elevated concentrations were caused by exceptional events. After an evaluation, we highlight all days that meet the initial criteria for exceptional event definition. If we determine that air quality data that has been impacted by exceptional events could impact a regulatory decision, such as designated an area as nonattainment we submit a full demonstration to EPA that documents how the event meets all EPA requirements. When EPA concurs, the data influenced by the exceptional events are not included when making regulatory decisions.

Motor vehicle emissions are one of the primary sources of air pollution in Idaho, particularly in urban areas such as the Treasure Valley. Areas that have violated the NAAQS need to develop an air quality plan, called a State Implementation Plan (SIP), to improve the air quality in that area. Pollution from transportation must be considered in the development of a SIP.

A collaborative process called transportation conformity ensures that transportation planning in the area is consistent with the air quality goals outlined in the SIP. Transportation conformity relies on the coordination of local, county, state and federal agencies through a workgroup called the interagency consultation committee (ICC). The ICC evaluates emissions from transportation plans, programs and projects to confirm that they will not worsen air quality.

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