2010 Ozone Standard Exceedances in National Parks

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.

The NPS tracks the days when the standard is exceeded in the parks. The table below displays the parks and the ozone values along with the number of days when the daily maximum 8-hour average ozone concentration exceeded the standard of 75 parts per billion (ppb)†. The fourth highest ozone column has been color-coded for easier viewing. The thumbnail on the right links to a map of parks with 2010 ozone exceedances.

2010 Ozone Standard Exceedances
National Park	April	May	June	July	Aug.	Sept.	Oct.	2010 Season
								Total Count	Max 8-hr O3 (ppb)	4th highest max. 8-hr O3 (ppb)
Acadia– Cadillac Mountain	0	1	0	0	0	2	0	3	89	75
Acadia– McFarland Hill	0	0	0	0	0	1	0	1	90	70
Assateague– Maintenance Area	0	0	0	2	1	0	0	3	100	75
Cape Cod– State Site	0	0	1	1	0	1	0	3	86	73
Canyonlands– Island in the Sky	0	0	1	0	0	0	0	1	76	68
Chickamauga/Chatanooga– Lookout Mountain	3	1	0	0	0	3	1	8	83	80
Cowpens– State Monitor	3	0	0	0	0	0	0	3	77	72
Death Valley– Park Village	0	0	0	0	0	1	0	1	76	69
Great Basin– Maintenance Yard	0	0	0	0	1	0	0	1	77	69
Great Smoky Mountains– Clingman's Dome	0	2	0	3	0	1	1	7	84	77
Great Smoky Mountains– Cade's Cove	1	0	0	0	0	1	0	2	78	73
Great Smoky Mountains– Cove Mountain	5	3	0	0	0	1	2	11	81	79
Great Smoky Mountains– Look Rock	4	2	0	2	0	2	1	11	84	81
Joshua Tree– Black Rock	2	8	17	16	9	1	0	53	105	97
Joshua Tree– Cottonwood Canyon	0	1	7	0	0	0	0	8	80	78
Joshua Tree– Pinto Wells	0	1	4	1	0	0	0	6	82	76
Mammoth Cave– Houchin Meadow	2	0	0	0	0	0	0	2	78	75
Mesa Verde– Resource Management Area	0	1	0	0	0	0	0	1	77	66
Mojave– Kelso Mountains	0	0	3	1	0	0	0	4	80	77
Pinnacles– SW of East Entrance Stn.	0	0	0	0	0	1	0	1	77	71
Rocky Mountain– Long's Peak	1	0	3	1	1	0	0	6	82	77
Sequoia and Kings Canyon– Ash Mountain	0	0	8	23	19	14	2	66	99	94
Sequoia and Kings Canyon– Lower Kaweah	0	0	2	4	2	1	0	9	79	77
Shenandoah– Big Meadows	0	0	0	2	0	0	1	3	82	74
Yosemite– Mobile	0	0	0	0	1	1	0	2	81	73
Yosemite– Turtleback Dome	0	0	0	1	2	4	0	7	85	77
Validation Level *	2	2	2	2	2	2	2
*Validation level 0 indicates raw data. Validation level 1 indicates preliminary data. Validation level 2 indicates final, validated data. Counts of days with 8-hr average ozone greater than 75 ppb may change after the data is fully validated. The ozone season runs from April to October for the detailed current ozone conditions. During the winter, more limited numbers of locations and web products are available. †The current NAAQS is 75 ppb, daily maximum 8-hour average. The ozone standard is violated when the 3-year average of the annual fourth-highest daily maximum 8-hour average ozone concentration is greater than 75 ppb, which occurs when the 3-year average exceeds 75 ppb. An exceedance occurs when the daily maximum 8-hour average is greater than 75 ppb.

Archived Exceedance Summaries (pdf’s)

2006–1983 | 2003 | 2002 | 2001 | 2000

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Related Links

• Ozone Health Advisories
• Current Ozone & Weather Data
• Map of current ozone conditions across the United States
• Ozone Concentrations 1983–2006 (pdf, 20 KB)
• Ozone Health Effects