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Particle pollution in Washington's air

Ecology and local clean air agencies monitor particle pollution in the air to ensure it doesn't reach harmful levels.

Particle pollution is a mixture of tiny solids that come from wood stoves, vehicles, dust, and more. It's harmful to your health when breathed in. Strategies to reduce pollution levels have included promoting cleaner wood stoves and reducing outdoor burning  when possible.

Today, all areas of Washington meet the particle pollution air quality standards, but several areas are being watched closely because they are at risk of having unhealthy air.

Image of a fine particle in comparison to a human hair and a grain of sand.

A fine particle next to a human hair and grain of sand.

Particle pollution

Particle pollution, also called particulate matter (PM), is a mixture of tiny solids or liquid droplets that includes smoke, soot, dirt, and dust floating in the air. Common sources are:

  • Wood stoves and fireplaces
  • Vehicles
  • Dust from construction and agriculture
  • Outdoor burning
  • Industrial facilities
  • Wildfires

Some particles in the air are captured in the nose or sinuses, but smaller particles move deeper into lungs, causing health problems. For this reason, we monitor two specific size ranges of small particles:

  • PM10 — particles less than 10 micrometers
  • PM2.5 — particles less than 2.5 micrometers

Particle pollution in Washington

In the late 1980s and early 1990s, PM10 levels in several areas of Washington were high enough to violate national standards. Parts of Benton, King, Pierce, Spokane, Thurston, Yakima, and Walla Walla counties were not able to meet the PM10 standard. This is referred to as "nonattainment" (not meeting the standard).

We and our local partners worked to bring PM10 back to healthy levels with State Implementation Plans (SIPs). By 2005, all areas met the air quality standards.

As recently as 2009, PM2.5 levels in the Tacoma area rose high enough to violate the standard again. Our partners immediately began planning to bring particle pollution back to healthy levels. Key parts of the plan included:

  • Increased enforcement of burn bans.
  • Removal and replacement of older uncertified wood stoves.
  • Education about burn bans and alternatives to wood burning.
By 2015, particle pollution levels had declined enough so that the area once again met the national standard and are considered in attainment. See the areas currently under Maintenance SIPs.
Areas of concern for PM 2.5 map

Maintaining clean air

To make sure the air continues to meet the air quality standard, we and our partners monitor air and plan for the future. Today, we monitor particle pollution at over 50 locations in the state.

We currently have a total of 55 PM2.5 monitoring sites in Washington's Air Monitoring Network, including those that are run by our partner agencies and supported by us.

  • 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 and are used to inform agricultural burning decisions.
  • Six are in tribal areas. These are all run by our tribal partners.
  • One is in a natural rural location (Olympic Peninsula).

What you can do

To reduce pollution:

  • Drive less: carpool, use public transportation, bike, or walk.
  • Pay attention to burn bans. Don’t burn leaves, garbage, plastic, or rubber.
  • Turn off engine when waiting in a line or in a parking lot.
  • Use dry and seasoned wood in your fireplace or wood stove.

To avoid pollution:

  • Pay attention to air quality forecasts and current air quality as you plan outdoor activities. On days when air quality is unhealthy, choose a less difficult, reschedule, or shorten outdoor activity.

To reduce indoor pollution:

Environmental effects

Particle pollution can be transported over long distances by wind and land, in water or on the ground. This causes:

  • Streams to become acidic.
  • A change in the nutrient balance in coastal water and large river basins.
  • Deficiencies in soil nutrients in the soil.
  • Damage to forests and crops.
  • A change in ecosystem diversity.

Health effects