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


Ozone Standard Exceedances in National Parks

Map of 2016 Ozone Exceedances - Season to Date
Map of 2016 Ozone Exceedances (Click photo to enlarge)

The National Park Service (NPS) actively monitors ozone at its parks from April to October. Ozone measurements are compared with the National Ambient Air Quality Standard (NAAQS) for ozone. The Environmental Protection Agency (EPA) sets this standard as the level at which the ozone in the air becomes unhealthy.

On October 1, 2015, the EPA strengthened the national ozone standard by setting the new level at 70 ppb, daily maximum 8-hour average. The NPS tracks the days when the standard is exceeded in the parks. In accordance with the new standard, the table below displays the parks and the ozone values along with the number of days where the daily maximum 8-hour average ozone concentration exceeded 70 parts per billion (ppb). The thumbnail on the right links to a map of parks with 2016 ozone exceedances.

2016 Ozone Standard Exceedances

National Park April May June July Aug. Sept. Oct. 2016 Season
Total Count Max 8-hr O3 (ppb) 4th highest max.
8-hr O3 (ppb)
Acadia National Park– Cadillac Mountain 1 0 0 1 71 63
Acadia National Park– McFarland Hill 0 1 0 1 89 60
Cape Cod– 0 1 0 1 75 61
Chamizal– State Monitor 0 0 1 1 84 64
Chickamauga Chatanooga National Military Park– Lookout Mountain 0 0 1 1 75 67
Chiricahua National Monument– Entrance Station 0 1 0 1 71 62
Great Smoky Mountains National Park– Clingmans Dome 0 0 1 1 74 69
Great Smoky Mountains National Park– Cove Mountain 1 1 1 3 73 70
Great Smoky Mountains National Park– Look Rock 1 0 2 3 73 70
Ogden Dunes– Water Treatment Plant 1 0 1 2 78 66
Joshua Tree National Park– Black Rock 2 1 16 19 87 84
Joshua Tree National Park– Cottonwood Canyon 0 0 8 8 82 72
Joshua Tree National Park– Pinto Wells 1 0 2 3 71 70
Kings Mountain National Military Park– RAWS Station 1 0 1 2 71 65
Mojave National Preserve– Kelso Mountains 0 1 4 5 82 75
Rocky Mountain National Park– Long's Peak 0 0 3 3 80 69
Saguaro– East 0 2 0 2 72 67
Saratoga National Historical Park– Stillwater 0 3 0 3 76 67
Sequoia and Kings Canyon National Parks– Ash Mountain 0 2 22 24 96 86
Sequoia and Kings Canyon National Parks– Lower Kaweah 0 1 16 17 87 80
Shenandoah National Park– Big Meadows 1 0 0 1 73 64
Tonto National Monument– 0 2 0 2 71 70
Yosemite National Park– Turtleback Dome 0 0 1 1 75 64

Validation Level *

2

2

1

0

0

0

0

0

0

0


Annual Exceedance Summaries

2016 | 2015 | 2014 | 2013 | 2012 | 2011 | 2010 | 2009 | 2008 | 2007 | 2006 | 2005 | 2004

2003 (pdf, 137 KB) | 2002 (pdf, 146 KB) | 2001 (pdf, 136 KB) | 2000 (pdf, 133 KB)


Compiled Exceedance Summaries


Last Updated: July 08, 2016