National Park Service

Sonoran Desert I&M Network (SODN)

Air Quality

Air Quality graphic

Air Quality at Class I Parks

Monitoring Brief

Monitoring Protocol

Air Quality


Both the Clean Air Act and the National Park Service Organic Act protect air resources in national parks. Park resources affected by air quality include scenery and vistas, vegetation, water, and wildlife. Understanding changes in air quality can aid in interpreting changes in other monitored vital signs and support evaluation of compliance with legislative and reporting requirements. Two SODN parks, Chiricahua NM and Saguaro NP, are designated Class I areas under the Clean Air Act. Over the past three decades, the NPS has developed several internal and cooperative programs for monitoring various measures of air quality. SODN has identified several components of air quality as high-priority vital signs for monitoring. The networks will acquire and analyze data from existing stations and report on data specific to park units.

Parks Monitored

Information on air quality at all SODN parks can be found by visiting the website of the NPS Air Resources Division.

Monitoring Questions

  1. What are the conditions and spatial and temporal trends in ozone, nitrogen deposition, sulfur deposition, and visibility-reducing pollutants in network park units?
  2. How do ozone, nitrogen deposition, sulfur deposition, and visibility-reducing pollutants vary with associated vital signs (e.g., vegetation community composition, exotic plant status, climate)?


  • Annual concentration (mg/L) and deposition (kg/ha) of sulfate, nitrate, ammonium.
  • Diurnal concentration (ppb) of ozone.
  • Mean daily light extinction (%) and aerosol composition (% by class).

Management Applications

Because emission of harmful air pollutants occurs over broad spatial scales, park managers have little direct control over the atmospheric conditions of the parks they manage. However, documenting the status and trends of air quality constituents can provide managers with regulatory and policy tools to influence off-site emitters and indirectly stabilize or improve park air resources. Accounting for the potential effects of air quality may also help clarify the consequences of stressors that park managers can directly affect.

Protocol Status

This protocol, developed in cooperation with the Chihuahuan Desert Network and Southern Plains Network through the Southwest Network Collaboration, has been approved and published.

Status & Trends

Determination of air quality status and trends is ongoing using current and archived data, and is performed primarily by the NPS Air Resources Division, though SODN may produce occasional updates.

Project Cooperators

Chihuahuan Desert Network
Southern Plains Network

Project Contacts

Andy Hubbard, SODN Program Manager
Alice Wondrak Biel, SODN Science Writer and Editor

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Last Updated: May 20, 2016 Contact Webmaster