2004 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 level of the National Ambient Air Quality Standard (NAAQS) for ozone in 2004 was 80 part per billion (ppb), daily maximum 8-hour average. The ozone standard was exceeded at an ambient air quality monitoring site when the 3-year average of the annual fourth-highest daily maximum 8-hour average ozone concentration was greater than 85 ppb, which occurred when the 3-year average equaled or exceeded 85 ppb. The table below counts the number of days when the daily maximum 8-hour average ozone concentration equaled or exceeded 85 ppb in 2004.

2003–2005 Average Annual 4th Highest Daily Maximum for
NPS Units (pdf, 130 KB) »

2004 Ozone Standard Exceedances
National Park	April	May	June	July	Aug.	Sept.	Oct.	2004 Season
								Total Count	Max 8-hr O3 (ppb)	4th highest max. 8-hr O3 (ppb)
Acadia NP – McFarland Hill	0	0	0	0	0	0	0	0	79	73
Big South Portable	0	0	0	1	3	0	0	4	115	87
Black Canyon Portable	0	1	0	0	0	0	0	1	91	80
Great Smoky Mountains – Cades Cove	0	0	0	0	0	0	0	0	70	66
Great Smoky Mountains – Clingman’s Dome	0	0	0	0	0	0	0	0	83	76
Great Smoky Mountains – Cove Mountain	0	0	0	1	0	0	0	1	86	74
Great Smoky Mountains – Look Rock	0	2	0	0	0	0	0	2	86	82
Gulf Island Portable	0	0	0	0	2	0	0	2	96	73
Joshua Tree – Yucca Valley	1	6	12	8	3	1	0	31	107	102
Lake Mead – Meadview	1	1	0	0	0	0	0	2	90	80
Mammoth Cave – Houchin Meadow	0	0	0	0	0	0	0	0	72	70
Pinnacles – East Entrance Station	0	0	0	0	0	0	0	0	83	77
Rocky Mountain – Long’s Peak Station	0	0	0	0	0	0	0	0	76	73
Sequoia & Kings Canyon – Ash Mountain	0	3	14	7	15	8	5	52	103	99
Sequoia & Kings Canyon – Lookout Point	0	4	12	18	11	4	1	50	101	95
Sequoia & Kings Canyon – Lower Kaweah	0	0	0	10	8	5	1	24	99	95
Shenandoah – Big Meadows	0	0	0	1	0	0	0	1	87	75
Yosemite – Turtleback Dome	0	1	1	5	0	1	0	8	124	89
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 85 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.

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