Determining if areas in Washington meet national air quality standards

Ecology must designate whether areas of Washington meet six national air quality standards. An area can be classified in one of three categories.

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)
  • Non-attainment (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.

New designations

When EPA sets or revises an air quality standard, we must determine whether the state meets the new standard.

Areas of concern

Currently, 100 percent of the state meets national air quality standards, but we have 12 communities at risk of violating standards.

The purple-shaded regions on the map represent the areas where we are at risk of violating ground level ozone standards.

The orange pentagons on the map represent the areas at risk of violating standards for fine particles (particulate matter). The size of the pentagon indicates the population size and the color intensity indicates the intensity of the fine particle pollution level in the areas.

If these areas don't meet the standard (nonattainment), then about 65 percent of Washington residents would live where air quality does not meet federal standards.

Areas of Concern for fine particles and ozone

Areas of concern for ozone and particle pollution

Ozone (O3)

In 2015, EPA revised the ozone standard. We issued our recommendation in 2016. Although all areas of Washington meet the ozone air quality standard, we are closely watching two problem areas:

  • Western foothills of Cascade Mountains
  • Tri-Cities area (Kennewick, Pasco, Richland)

Particle pollution (PM10 and PM2.5)

Particle pollution in the areas on the map comes primarily from wood stoves used to heat homes.

The 200,000 uncertified wood stoves in Washington are the biggest contributors. It’s important to continue investing in these at-risk communities. Developing local solutions that work for each community can help prevent future violation of federal air quality standards.

Sulfur Dioxide (SO2)

New sulfur dioxide standard coming soon (2017).