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Air Pollution Impacts

Olympic National Park

Natural and scenic resources in Olympic National Park (NP) are susceptible to the harmful effects of air pollution. Mercury, fine particles, nitrogen, and ozone impact natural resources such as lakes, streams, fish, amphibians, and vegetation, and scenic resources such as visibility. Click on the tabs below to learn more about air pollutants and their impacts on natural and scenic resources at Olympic NP.

  • Toxics & Mercury
  • Visibility
  • Nitrogen & Sulfur
  • Ozone
Photo of a rainbow trout at Olympic NP in Washington
Fish such as rainbow trout at Olympic NP, Washington, are susceptible to mercury contamination.

Toxics, including heavy metals like mercury, accumulate in the tissue of organisms and may alter key ecosystem processes. When mercury converts to methylmercury in the environment and enters the food chain, effects can include reduced reproductive success, impaired growth and development, behavioral abnormalities, reduced immune response, and decreased survival. Human activities have greatly increased the amount of mercury in the environment through processes such as burning coal for electricity and burning waste. Other toxic air contaminants of concern include pesticides, industrial by-products, and emerging chemicals. Some of these toxics are also known or suspected to cause cancer or other serious chronic health effects in humans and wildlife, including fish and amphibians.

Effects of mercury and airborne toxics on ecosystems at Olympic NP include:

  • Presence of contaminants including mercury, current-use pesticides, historic-use pesticides, and industrial by-products in snow, sediment, vegetation, and fish (Frenzel et al. 1990; Hageman et al. 2006; Moran et al. 2007; Landers et al. 2010; Landers et al. 2008);
  • Mercury concentrations in fish are among the highest of eight western and Alaskan national parks studied, exceeding safe consumption thresholds for wildlife and humans; levels are associated with tissue damage in fish kidney and spleen (Landers et al. 2010; Landers et al. 2008; Schwindt et al. 2008);
  • Fish from “contaminated” lakes (i.e., elevated mercury, DDE, and PCBs) in Washington’s high elevation national parks including Olympic NP displayed changes in metabolic, endocrine, and immune-related genes, as compared to fish from uncontaminated lakes (Moran et al. 2007);
  • High mercury levels in largemouth bass from Lake Ozette (inside the park) and Lake Dickey (outside the park), a finding that coincides with logging in the lakes’ drainages which has greatly increased the amount of mercury entering the waterbodies (Furl et al. 2009).

Get Toxics Data »


Three images depicting air quality impacts on visibility at Olympic National Park, Washington (clear to hazy from top to bottom).
Air pollutants can affect visibility at Olympic NP, Washington (clear to hazy from top to bottom).

Many visitors come to Olympic NP to enjoy views of the rugged Olympic Mountains. Unfortunately, these vistas are often obscured by haze caused by fine particles in the air. Many of the same pollutants that ultimately fall out as nitrogen and sulfur deposition contribute to this haze and visibility impairment. Organic compounds, soot, and dust reduce visibility as well.

Visibility effects at Olympic NP include:

  • Reduction of the average natural visual range from about 140 miles (without the effects of pollution) to about 70 miles because of pollution at the parks;
  • Reduction of the visual range from about 100 miles to below 45 miles on high pollution days;
  • Human-caused haze sometimes impairs scenic vistas at the park.

(Source: IMPROVE 2010)

Additional Information:

  • Explore scenic vistas through a live webcam at Olympic National Park!
  • Learn about PREVENT, the Pacific Northwest Regional Visibility Experiment Using Natural Tracers special study. This 1990 study investigated the contribution of emission sources to fine particle concentrations and regional haze. more »

Get Visibility Data » 


Nitrogen and sulfur compounds deposited from air pollution may harm lakes, streams, soils, and vegetation. In Olympic NP, rates of nitrogen and sulfur deposition are low. However, even low rates of deposition have been found to harm resources in similar areas. Nitrogen can cause changes to plant communities, with increases in annual grasses and decreases in native species. Over-fertilization by nitrogen can also affect fish and amphibian populations. The eastern side of the park may be most susceptible to harmful effects of nitrogen due to the relative location to pollution sources (urban areas, industry, marine vessels) from the Puget Sound area (Eilers et al. 1994 [pdf, 520 KB]).

How much nitrogen is too much?

Photo of lichen (Cladonia ecmocyna) in Olympic NP in Washington.
While nitrogen deposition at Olympic NP, Washington, is relatively low, even slight loading to the ecosystem can affect sensitive lichen species.

Nitrogen is a fertilizer and some nitrogen is necessary for plants to grow. However, in natural ecosystems, too much nitrogen disrupts the balance of plant and aquatic communities, allowing weedy species to grow faster. In some areas of Washington State, including the Columbia River Gorge and the Willamette Valley, high levels of nitrogen deposition have changed lichen communities. In those areas, lichens adapted to low nitrogen conditions are being replaced by lichens adapted to a more disturbed, polluted environment (Geiser et al. 2010). Surveys in Olympic NP have found that current nitrogen deposition rates in the park are low and have not affected lichens. However, lichens can serve as an early warning system if nitrogen deposition increases on the peninsula. Similarly, the composition of sensitive aquatic communities can provide early warning signs of nitrogen deposition effects to waterbodies.

Get Sulfur & Nitrogen Data »


Photo of spreading dogbane in Olympic NP in Washington.
Spreading dogbane, a species sensitive to ozone injury at Olympic NP, Washington.

Naturally-occurring ozone in the upper atmosphere absorbs the sun’s harmful ultraviolet rays and helps to protect all life on earth. However, in the lower atmosphere, ozone is an air pollutant, forming when nitrogen oxides from vehicles, power plants and other sources combine with volatile organic compounds from gasoline, solvents, and vegetation in the presence of sunlight. In addition to causing respiratory problems in people, ozone can injure plants. Ozone enters leaves through pores (stomata), where it can kill plant tissues, causing visible injury, or reduce photosynthesis, growth, and reproduction.

Ozone is transported to Olympic National Park from the Puget Sound urban zone and trans-Pacific sources (Barna et al. 2000; Jaffe et al. 2003). Marine vessel traffic in the Strait of Juan De Fuca also contributes to ozone pollution in the region. However, ozone transport is limited and the Olympic Peninsula has some of the lowest measured ozone concentrations in the Western U.S. (Bohm 1992). While several park species including Populus tremuloides (quaking aspen) and Apocynum androsaemifolium (spreading dogbane) are known to be sensitive to ozone (Brace et al. 1999), concentrations at the park are below levels known to be harmful to plants (Eilers et al. 1994 [pdf, 520 KB]).

Search the list of ozone-sensitive plant species (pdf, 184 KB) found at each national park.

Get Ozone Data »


Featured Content

Studies and Monitoring icon

Studies and monitoring help the NPS understand the environmental impacts of air pollution. Access air quality data and see what is happening with Studies and Monitoring at Olympic NP.

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Last Updated: December 30, 2016