For more information about National Park Service air resources, please visit http://www.nature.nps.gov/air/.


Health Advisories Issued for National Parks

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Whenever ozone or particulate matter concentrations exceed or are predicted to exceed health standards, National Park Service (NPS) staff post health advisories cautioning visitors of the potential health risks associated with exposures to elevated levels. Most air pollution in National Parks is created outside park boundaries. When air quality conditions reach unhealthy levels in parks, conditions in the surrounding areas are usually similar.

Ozone Advisories

The NPS issues ozone health advisories when ozone concentrations are predicted to or exceed the National Ambient Air Quality Standard. The ozone health standard is based on an 8-hour average concentration set at 70 parts per billion (ppb). Due to rounding, EPA considers an exceedance of the 8-hour standard when the ozone concentration exceeds 75 ppb. Using the EPA air quality index , the NPS ozone health advisories are based on the levels shown below. Health Effects of Ozone »

Air Quality Index (ppb) diagram for ozone

Fine Particulate Matter Advisories

Air quality in some parks may at times exceed the National Ambient Air Quality Standard for fine particulate matter (PM 2.5 ), particles less than or equal to 2.5 micrometers (µm). The 24-hour public health standard set at 35 micrograms per cubic meter parts (µg/m 3 ) is used as a basis for health advisories in the parks. Using the EPA air quality index , the NPS PM 2.5 health advisories are based on the levels shown below. Health Effects of Particulate Matter »

Air Quality Index (ppb) diagram for particulate matter

Participating Parks

The NPS issues air quality health advisories at several national parks. These parks include:

  • Acadia NP
  • Great Smoky Mountains NP
  • Mammoth Cave NP
  • Pinnacles NM
  • Rocky Mountain NP
  • Sequoia & Kings Canyon NPs
  • Shenandoah NP
  • Yosemite NP

Ozone Health Advisory Program Summaries

2013 | 2012 | 2011 | 2010 | 2009 | 2008 | 2007 | 2006 | 2005 | 2004

Related Links

Last Updated: August 11, 2014