We focus our work on six common air pollutants (called "criteria air pollutants") which EPA sets in National Ambient Air Quality Standards (NAAQS):
Using air monitoring data, we must determine whether an area meets each standard. This is called a designation. Then we recommend that designation to EPA.
The federal Clean Air Act says there are three ways to classify air quality:
- Attainment (meeting a standard)
- Nonattainment (not meeting a standard)
- Unclassifiable (not enough information to classify)
Each designation is for a specific air quality standard. An area can be in attainment for one standard, and be in nonattainment or unclassifiable for another. If an area does not meet a standard, then we must follow a state implementation plan to bring that area back into attainment. When EPA sets or revises an air quality standard, we must determine whether the state meets the new standard.
Maintaining clean air
All areas of Washington, except a small area in Whatcom County, currently meet air quality standards. Several areas are being watched closely. We and other clean air agencies monitor the air using Washington's air monitoring network at 55 locations.
- Twenty-two are in urban areas (the Puget Sound region, Vancouver, Spokane and Yakima Counties, and the Tri-Cities).
- Nineteen are in small communities outside of urban areas that have local sources of PM2.5 pollution.
- Seven are in agricultural areas to help us make decisions about agricultural burning.
- Six are in tribal areas.
- One is in a natural rural location (Olympic Peninsula).
Areas of concern for criteria pollutants map