National Park Service

Appalachian Highlands Network (APHN)

Air Quality Monitoring

Air quality comparison photos from the Smoky Mountains
Air quality comparison photos from the Smoky Mountains View from Look Rock Web Cam Looking East (GRSM)

Resource Brief: Air Quality Monitoring in APHN

Air Quality Inventory Reports

Air Quality Monitoring Protocols & Procedures

National & Regional Data & Map Products

NPS Air Atlas
A series of web maps that provide visualization of estimated air quality statistics for parks located in the 48 contiguous United States.

For more information contact: Jim Renfro or Ellen Porter.

Affected Parks

  • Big South Fork National River & Recreation Area (BISO)
  • Blue Ridge Parkway (BLRI)
  • Obed Wild & Scenic River (OBRI)
  • Great Smoky Mountains National Park (GRSM)

Importance / Issues

The National Park Service strives to perpetuate the best possible air quality in units of the National Park System. Progress toward this goal is measured by examining trends for key air quality indicators, including:

  • Ozone
  • Visibility
  • Atmospheric deposition,which affects ecological health through acidification and fertilization of soils and surface waters

The height and physical structure of the Southern Appalachian Mountains (the highest in eastern North America) combined with predominant weather patterns, tend to trap and concentrate anthropogenic pollutants such as those produced by fossil fuel combustion in power plants, factories, and automobiles. Great Smoky Mountains National Park (GRSM) experiences some of the highest deposition rates of sulfur and nitrogen in North America. Despite declining national trends, sulfur dioxide emissions affecting the Southern Appalachians have increased in the past two decades, with deleterious effects on air quality and visibility.

These pollutants are deposited in the form of rainfall, dry particles and cloud water. The average annual pH of rainfall in the Smokies is ten times more acidic than natural rainfall. Clouds with acidity as low as pH 2.0 bathe high elevation forests during much of the growing season. Some high-elevation park streams have the highest nitrate levels of any systems in the U.S. that drain undisturbed watersheds.

Research in the Smokies has shown that some high-elevation soils in the park are receiving so much airborne nitrogen that they are suffering from advanced nitrogen saturation. This limits the availability of nutrients to forest plants and causes the mobilization of toxic ions such as aluminum that can harm vegetation and aquatic biota. It is suspected that similar conditions may exist in the high-elevation portions of BLRI.

In the Appalachian Highlands Network (APHN), Great Smoky Mountain National Park is a designated Class I air quality area, while the other three network parks are Class II air quality areas. GRSM has on-site ambient air quality monitoring; the other parks have nearby monitors. The air pollution issues of most significant concern for the APHN are ozone, acid deposition and visibility are in proposed 8-hour ozone non-attainment areas. An ozone injury risk assessment indicates that the risk of injury is high in the Smokies and on the Blue Ridge Parkway.

Air Quality Monitoring In and Near APHN Parks

Ozone, sulfur dioxide, dry deposition, and meteorology are collected by the Clean Air Status and Trends (CASTNet) and Gaseous Pollutant Monitoring (GPMN) networks. Ozone is also monitored with passive samplers and portable continuous analyzers. Wet deposition is monitored through cooperation with National Atmospheric Deposition Program/National Trends Network (NADP/NTN). The Mercury Deposition Network (MDN), part of NADP, collects precipitation samples that are analyzed for mercury. Visibility is monitored as part of the Interagency Monitoring of Protected Visual Environments (IMPROVE)

Monitoring Objectives

Specific objectives are to:

  1. Report on seasonal and annual trends in nitrogen and sulfur deposition at existing monitoring stations in and near APHN parks.
  2. Report on seasonal and annual trends in fine particle concentration at existing monitoring stations in and near APHN parks.
  3. Report on seasonal and annual trends in ozone concentration near APHN parks using metrics that are indicative of human health (e.g., 8-hour average) and plant response (e.g., SUM06).

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Last Updated: October 05, 2017 Contact Webmaster