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

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

Share of days with good air quality (US EPA AQI) in Union County was 100% in 2016, according to EPA. That is up 5.8 pts from 2015.

2016100%
Change on 2015+5.8 pts
Series high1001988
Series low65.61998

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 Union County, 1988 to 2016

607080901001988199319982003200820161988: 100 %1989: 91.8 %1990: 86.9 %1991: 87.9 %1992: 98.2 %1993: 98.3 %1994: 88.3 %1995: 86.7 %1996: 89.4 %1997: 68.5 %1998: 65.6 %1999: 73.6 %2000: 83 %2001: 82.7 %2002: 83.6 %2003: 76.1 %2004: 75.6 %2005: 87.6 %2006: 83.8 %2007: 83.8 %2008: 86.3 %2009: 98.9 %2010: 93.1 %2011: 94.2 %2012: 97 %2013: 98.6 %2014: 97.3 %2015: 94.2 %2016: 100 %6070809010019881998200820161988: 100 %1989: 91.8 %1990: 86.9 %1991: 87.9 %1992: 98.2 %1993: 98.3 %1994: 88.3 %1995: 86.7 %1996: 89.4 %1997: 68.5 %1998: 65.6 %1999: 73.6 %2000: 83 %2001: 82.7 %2002: 83.6 %2003: 76.1 %2004: 75.6 %2005: 87.6 %2006: 83.8 %2007: 83.8 %2008: 86.3 %2009: 98.9 %2010: 93.1 %2011: 94.2 %2012: 97 %2013: 98.6 %2014: 97.3 %2015: 94.2 %2016: 100 %
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12, published 2026-07-13.
All 29 values
Period%
2016100
201594.2
201497.3
201398.6
201297
201194.2
201093.1
200998.9
200886.3
200783.8
200683.8
200587.6
200475.6
200376.1
200283.6
200182.7
200083
199973.6
199865.6
199768.5
199689.4
199586.7
199488.3
199398.3
199298.2
199187.9
199086.9
198991.8
1988100

Union County compared with nearby places

Anderson County: 83 %Blount County: 74.6 %Claiborne County: 93.3 %Davidson County: 40.4 %DeKalb County: 94 %Dyer County: 79.2 %Hamilton County: 62.2 %Jefferson County: 66.1 %Knox County: 45.6 %Lawrence County: 84.5 %Loudon County: 60.7 %McMinn County: 63.9 %Madison County: 76.5 %Maury County: 80.9 %Montgomery County: 70.8 %Putnam County: 71.3 %Roane County: 59.8 %Sevier County: 83 %Shelby County: 58.5 %Sullivan County: 77.3 %Sumner County: 73.3 %Union County: 100 %Williamson County: 89.8 %Wilson County: 82.7 %
  • Under 62
  • 62 to 72
  • 72 to 79
  • 79 to 84
  • 84 and over
  • No data
Share of days with good air quality (US EPA AQI), 2016, %. Union 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), Union County, 1988 to 2016) [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), Union County, 1988 to 2016. 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/union-county-tennessee. 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), Union County, 1988 to 2016. 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/union-county-tennessee.

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), Union County, 1988 to 2016 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/good-air-quality-days-share/union-county-tennessee (Accessed: 12 October 2026).

BibTeX
@misc{environmental_share_of_days_with_2016,
  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), Union County, 1988 to 2016}},
  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/union-county-tennessee. 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), Union County, 1988 to 2016
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/union-county-tennessee
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/good-air-quality-days-share/union-county-tennessee.
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 Union County?

Share of days with good air quality (US EPA AQI) in Union County was 100% in 2016, according to EPA. That is up 5.8 pts from 2015.

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 Union County?

100% in 1988, the highest value since 1988 in this series.

Related statistics for Union County

All statistics for Union County | Union County in figures