Sulfur dioxide in Washington's air

We monitor air and track emissions from industrial sources to ensure sulfur dioxide levels meet health-based air quality standards.

Sulfur dioxide

Sulfur dioxide (SO2) gets into the air when fuel that contains sulfur is burned. Key sources in Washington include:

  • Industrial facilities such as fossil fuel power plants, aluminum smelters, and pulp mills
  • Ships and locomotives

Sulfur dioxide pollution in Washington

Although sulfur dioxide levels in Washington's air have never violated national standards, past levels would violate today's more stringent standards. Thanks to tighter controls on industrial facilities and cleaner fuels, Washington's sulfur dioxide levels have declined.

Maintaining clean air

To ensure air continues to meet today's standard, we monitor sulfur dioxide at six locations along with local clean air agencies. Locations include:

  • One location in Seattle representing urban and near road conditions.
  • One location in Anacortes.
  • Two locations near Intalco Aluminum Corporation in Whatcom County.
  • One location near Alcoa Wenatchee LLC near Malaga.
  • One location on the Olympic Peninsula representing rural background (or natural) conditions.

In addition to monitoring, we use air dispersion modeling to determine if emissions from TransAlta power plant in Centralia violate air quality standards. TransAlta has emitted high levels of air pollution in the past. 

What you can do

There are some things you can do to protect yourself from sulfur dioxide. You can:

  • Drive cleaner cars.
  • Upgrade old engines to cleaner ones.
  • Limit outdoor activities during times of high air pollution.
  • Close windows and vents during periods of high air pollution.
Environmental effects

Trees and plants can be harmed by sulfur dioxide in high concentrations. It can contribute to acid rain that harms sensitive ecosystems. When it reacts with fine particles in the air it reduces visibility, causing a haze.

Health effects