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Regional Haze InformationHave you ever looked up expecting to see a breathtaking view of Mount Rainier, the Columbia River Gorge, or the Palouse Falls, and been disappointed to see an ugly brown or white haze ruining the view? It's called "regional haze," and it's air pollution. Regional haze has reduced scenic views in national parks and wilderness areas from an average of 140 miles down to 35-90 miles in the western U.S.; and from an average of 90 miles down to 15-25 miles in the eastern U.S. The photos below show the same view, looking west from the slopes of Mt. Rainier, with and without regional haze.
Haze is caused when tiny particles in the air absorb and scatter sunlight between the object we are looking at (such as Mt. Rainier) and our eyes. More particles means more light is either absorbed or scattered, reducing the clarity and color of what we see. Where do fine particles come from? The particles that cause haze come from both natural and human-caused sources. Natural sources include windblown dust and soot from wildfires or other burning. Human-caused sources include motor vehicles, electric utility and industrial fuel burning, and manufacturing operations. Some of the particles that cause haze are emitted directly to the air. Others are formed from gases that are carried many miles from their source. This is why we often see haze in areas that don't usually have other kinds of air pollution. Fine particles have also been linked to serious health problems and environmental damage. Learn more about fine particle pollution.
We measure visibility by collecting and analyzing particles in
the air as part of the Interagency Monitoring of Protected
Visual Environments (IMPROVE) monitoring network. In
Washington, there are 10 IMPROVE monitoring sites. One 24-hour
air sample is collected at each site every three days, providing
a total of 121 samples each year from each site.
Once the samples are collected, we analyze them for substances such as sulfate, nitrate, carbon-containing particles, and dirt and sand, all of which affect visibility. We calculate visibility based on the types and amounts of substances in the particles. We show visibility in one of two ways:
Another way to measure visibility is by using an instrument such as a nephelometer. What are we doing about regional haze? The federal Clean Air Act requires states to protect and improve visibility in national parks and wilderness area. The Clean Air Act has set a goal of returning visibility in these areas to natural conditions by the year 2064. Congress designated 156 national parks and wilderness areas as "mandatory federal Class 1 areas" where visibility is especially important. All states must submit plans to EPA to reduce air pollutants that affect visibility in their Class 1 areas. Washington has eight Class 1 areas, totaling more than 3.3 million acres of land. They are:
What is Ecology doing to improve visibility in Washington? Ecology is writing a regional haze State Implementation Plan (SIP). This plan will document current conditions at our Class 1 areas and define a strategy for returning visibility at these sites to natural conditions by 2064, as required by the Clean Air Act. Ecology is working closely with other states and organizations to write this plan, mostly through the Western Air Regional Partnership (WRAP). More information on visibility and regional haze You can find more information at the following web sites:
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Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.html.
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