Data / Share of days with good air quality (US EPA AQI) / Summit County

Share of days with good air quality (US EPA AQI) in Summit County

Share of days with good air quality (US EPA AQI) in Summit County was 96.7% in 2012, according to EPA. That is down 2 pts from 2011.

201296.7%
Change on 2011-2 pts
Series high99.72010
Series low86.51994

Next release: Tuesday, 13 July 2027, estimated by Invokely from past publication dates (low confidence), not announced by the publisher. Release calendar

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Share of days with good air quality (US EPA AQI) in Summit County, 1992 to 2012

85909510019921995199820012004200720121992: 96.6 %1993: 87.5 %1994: 86.5 %1995: 92.2 %1996: 96.6 %1997: 96.8 %1998: 96.5 %1999: 98.3 %2000: 94.2 %2001: 91.8 %2002: 95.1 %2003: 96.7 %2004: 96.4 %2005: 92.5 %2006: 97.1 %2007: 97.2 %2008: 98.2 %2009: 98.5 %2010: 99.7 %2011: 98.7 %2012: 96.7 %85909510019921999200620121992: 96.6 %1993: 87.5 %1994: 86.5 %1995: 92.2 %1996: 96.6 %1997: 96.8 %1998: 96.5 %1999: 98.3 %2000: 94.2 %2001: 91.8 %2002: 95.1 %2003: 96.7 %2004: 96.4 %2005: 92.5 %2006: 97.1 %2007: 97.2 %2008: 98.2 %2009: 98.5 %2010: 99.7 %2011: 98.7 %2012: 96.7 %
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12, published 2026-07-13.
All 21 values
Period%
201296.7
201198.7
201099.7
200998.5
200898.2
200797.2
200697.1
200592.5
200496.4
200396.7
200295.1
200191.8
200094.2
199998.3
199896.5
199796.8
199696.6
199592.2
199486.5
199387.5
199296.6

Summit County compared with nearby places

Adams County: 58.2 %Alamosa County: 90.2 %Arapahoe County: 54.5 %Archuleta County: 98.2 %Boulder County: 51.5 %Chaffee County: 47.8 %Clear Creek County: 8.7 %Delta County: 98.3 %Denver County: 40.2 %Douglas County: 54.9 %El Paso County: 56.8 %Fremont County: 98.2 %Garfield County: 38.8 %Gunnison County: 69.4 %Jackson County: 90.6 %Jefferson County: 54.9 %La Plata County: 59.6 %Larimer County: 43.7 %Mesa County: 51.9 %Moffat County: 73.7 %Montezuma County: 65 %Park County: 67.9 %Pitkin County: 96.7 %Prowers County: 93.4 %Pueblo County: 87.2 %Rio Blanco County: 47.8 %Routt County: 98 %San Juan County: 97.5 %San Miguel County: 78 %Summit County: 96.7 %Weld County: 53.6 %
  • Under 48
  • 48 to 55
  • 55 to 65
  • 65 to 87
  • 87 to 97
  • 97 and over
  • No data
Share of days with good air quality (US EPA AQI), 2012, %. Summit County is outlined. Same source and period for every area shown. Source: U.S. Environmental Protection Agency. Boundaries: U.S. Census Bureau cartographic boundary files.

Rankings

Definition

Days with a daily Air Quality Index of 0 to 50 (good) as a percentage of the days of the year with an AQI in a US county. Calculated by Invokely from the day counts in the EPA AirData annual summaries; both counts are stored with each value.

United States counties with air quality monitors only, about 1,000 of some 3,100 in recent years; a county without monitors has no value. The number of days with an AQI differs between counties because some monitors run only in the ozone season.

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How to cite

U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Environmental Protection Agency. (2026). EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts (Share of days with good air quality (US EPA AQI), Summit County, 1992 to 2012) [Data set]. Retrieved October 12, 2026, from https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual

MLA 9

EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Share of days with good air quality (US EPA AQI), Summit County, 1992 to 2012. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/en/good-air-quality-days-share/summit-county-colorado. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Share of days with good air quality (US EPA AQI), Summit County, 1992 to 2012. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/en/good-air-quality-days-share/summit-county-colorado.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Share of days with good air quality (US EPA AQI), Summit County, 1992 to 2012 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/good-air-quality-days-share/summit-county-colorado (Accessed: 12 October 2026).

BibTeX
@misc{environmental_share_of_days_with_2012,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts: Share of days with good air quality (US EPA AQI), Summit County, 1992 to 2012}},
  year = {2026},
  howpublished = {Data set},
  url = {https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/en/good-air-quality-days-share/summit-county-colorado. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. https://aqs.epa.gov/aqsweb/airdata/download\_files.html\#Annual. Retrieved 2026-10-12.},
}
RIS
TY  - DATA
AU  - U.S. Environmental Protection Agency
TI  - EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts: Share of days with good air quality (US EPA AQI), Summit County, 1992 to 2012
PY  - 2026
DA  - 2026/07/13
PB  - U.S. Environmental Protection Agency
DB  - Invokely
UR  - https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual
L2  - https://invokely.ai/en/good-air-quality-days-share/summit-county-colorado
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/good-air-quality-days-share/summit-county-colorado.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Questions

What is the share of days with good air quality (US EPA AQI) in Summit County?

Share of days with good air quality (US EPA AQI) in Summit County was 96.7% in 2012, according to EPA. That is down 2 pts from 2011.

Where does this figure come from?

U.S. Environmental Protection Agency. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Retrieved by Invokely on 2026-10-12.

What was the highest share of days with good air quality (US EPA AQI) in Summit County?

99.7% in 2010, the highest value since 1992 in this series.

Related statistics for Summit County

All statistics for Summit County | Summit County in figures