Department of
Environmental Quality

Based upon levels of air pollutants, geographic areas are classified by EPA as attainment or nonattainment areas.

• A geographic area that meets or has pollutant levels below the NAAQS is called an attainment area.
• An area with persistent air quality problems is designated a nonattainment area. This means that the area has violated federal health-based standards for outdoor air pollution.

Each nonattainment area is declared for a specific pollutant. Nonattainment areas for different pollutants may overlap each other or share common boundaries.

States strive to achieve attainment with state and federal air quality standards for a number of reasons. First and foremost, remaining in compliance helps protect public health, a key element of Idaho DEQ's mission. In addition, compliance contributes to economic growth. Nonattainment status can potentially limit production capabilities of existing industries and preclude siting of new industries that provide job opportunities. Attainment of air quality standards also helps avoid a potential loss of federal highway funding that can result from nonattainment status. Lastly, it is costly and time-consuming to develop and implement plans to reattain attainment status.

In addition to areas classified as attainment and nonattainment, some areas are described as "maintenance areas." Maintenance areas are those geographic areas that were classified as nonattainment, but are now consistently meeting the NAAQS. Maintenance areas have been re-designated by the EPA from "nonattainment" to "attainment with a maintenance plan"; commonly called "maintenance areas." These areas have demonstrated through monitoring and modeling they have sufficient controls in place to meet and main the NAAQS. They also have contingency measures in place that would be implemented should the areas start showing exceedances.

Nonattainment and Maintenance Areas in Idaho

At present, the four geographical areas described below are classified as nonattainment or maintenance areas in Idaho.

• Idaho Air Quality Planning Areas Map: Shows nonattainment areas, areas of concern, and Class I areas (Class I areas include all national parks greater than 6,000 acres, wilderness areas and national memorial parks greater than 5,000 acres, and certain international parks.)

Sandpoint - PM10

Located in Bonner County, the area rests on the northwest corner of Lake Pend Oreille within the Panhandle National Forest. The topography influences much of the PM buildup in the area. In 1997, the area was designated moderate PM10 nonattainment, and an emissions inventory identified the primary PM10 source as residential wood burning. Fugitive road dust and some industrial sources are also considered significant contributors. Since 1997, significant improvements in air quality have been realized thanks to the efforts of the community. In December 2011, DEQ submitted a request to EPA to re-designate the area to “Attainment” status. 

• Sandpoint PM10 Nonattainment Area Plan
• Sandpoint Nonattainment Area Map
  

Pinehurst - PM10

Located in Shoshone County and rests in the Silver Valley surrounded by the Coeur d'Alene and St. Joe National Forests. The area's topography is a significant factor in the buildup of pollutants that result in poor air quality. The emission inventory identified residential wood burning as the primary PM10 source and fugitive road dust as a secondary source.

• Pinehurst PM10 Nonattainment Area Plan

Portneuf Valley (Maintenance Area) - PM10

This area consists of 96.6 square miles of Pocatello, Chubbuck, and surrounding areas. It was formerly the Power/Bannock County PM10 area, which was split into the Portneuf Valley and federal Fort Hall PM10 areas. It includes federal land managed by the Bureau of Land Management and the Caribou National Forest, as well as privately owned land in the cities of Pocatello and Chubbuck.

• Portneuf Valley PM10 Nonattainment Area State Implementation Plan, Maintenance Plan, and Redesignation Request

Northern Ada County (Maintenance Area) - Carbon Monoxide and PM10

At present, Northern Ada County is a Limited Maintenance Area for CO. Northern Ada County is Idaho's only designated CO Maintenance Area. Mobile and area source emissions are the two major sources of CO. Northern Ada County is also a Maintenance Area for PM10. The main sources of PM10 are fugitive road dust and agriculture.

• Limited Maintenance Plan and Request for Redesignation to Attainment for the Northern Ada County Carbon Monoxide Not-Classified Nonattainment Area | Appendices
• Northern Ada County PM10 SIP Maintenance Plan and Resdesignation Request
  

Redesignating Nonattainment Areas

Several nonattainment areas in Idaho now appear to be meeting NAAQS. This apparent compliance with the federal standards does not automatically bring an area's nonattainment status to an end, however. The Clean Air Act requires states to follow an extensive process to prove that the nonattainment designation should be removed.

DEQ and local governments are working to gain redesignation in all areas that are meeting outdoor air quality standards. Redesignation is a complicated and lengthy process that can take up to two years for each area. To attain reclassification, the nonattainment area must meet national ambient air quality health standards as follows:

• Coarse particulate matter (PM10) and ground-level ozone: No more than an average of one violation of the standard per year for three consecutive years.

• Carbon Monoxide: No more than one violation of the standard each year for two consecutive years (averaging prohibited; cannot have two violations one year and none the next).

Data must be acquired through actual monitoring with equipment located in places likely to have the highest concentrations of the pollutant. A computer modeling analysis also must be completed to show that monitoring occurred in high concentration areas and to support the case that the standard has been met. Following are the steps that must be followed:

Develop a Nonattainment Area Plan

DEQ must complete and obtain EPA approval of a State Implementation Plan (SIP) for bringing each area into attainment. The federal planning process must be completed before completing other redesignation requirements.

Demonstrate Proof of Real Pollution Reduction

DEQ must prove to EPA that the air quality improvements are permanent and enforceable. Improvements cannot be attributed to unusually favorable weather conditions or factors such as economic downturns that resulted in less traffic and industrial activity.

Develop a Maintenance Plan

DEQ must develop and obtain EPA approval of a maintenance plan designed to keep the area's air healthful. This plan must outline the pollution prevention steps that the state will implement to maintain air quality standards for 10 years after redesignation is attained. Circumstances will dictate whether fewer, the same, or additional pollution prevention strategies will be required. The plan also must describe measures that will be taken to correct violations if they occur. DEQ may submit the maintenance plan at the same time it applies for redesignation.

Other Requirements

• Inventory: DEQ must prepare an inventory showing all sources of air pollution and how much they generate. Sources are things such as vehicles, wood stoves, and commercial or industrial facilities that generate air pollution. DEQ must identify the maximum amount of emissions that can be allowed without violating air quality standards.
• Maintenance Demonstration: Using a computer model, DEQ must demonstrate to EPA's satisfaction that the maintenance plan will keep air quality within the federal standards for 10 years, even if the number of pollution sources increases (for example, increased traffic or more industrial areas in the area).
• Monitoring: DEQ must submit a monitoring plan that will show whether the federal standards are being maintained. The plan must allow for special studies in case traffic patterns or other pollution producing patterns change. These studies could lead to new permanent monitoring sites if high pollution persists.