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

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

Share of days with good air quality (US EPA AQI) in Marshall County was 68.7% in 2002, according to EPA. That is up 5.6 pts from 2001.

200268.7%
Change on 2001+5.6 pts
Series high68.72002
Series low52.61999

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 Marshall County, 1999 to 2002

505560657019992000200120021999: 52.6 %2000: 62 %2001: 63.1 %2002: 68.7 %5055606570199920021999: 52.6 %2000: 62 %2001: 63.1 %2002: 68.7 %
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12, published 2026-07-13.
All 4 values
Period%
200268.7
200163.1
200062
199952.6

Marshall County compared with nearby places

Adair County: 72.6 %Caddo County: 64.3 %Canadian County: 73.6 %Carter County: 63.6 %Cherokee County: 75.1 %Cleveland County: 80.2 %Comanche County: 71.2 %Custer County: 65.7 %Dewey County: 86.1 %Ellis County: 72.7 %Garfield County: 57.5 %Jefferson County: 68.8 %Kay County: 65.8 %Lincoln County: 62.5 %McClain County: 79.7 %Marshall County: 68.7 %Mayes County: 41.7 %Muskogee County: 73.4 %Oklahoma County: 43 %Ottawa County: 74.1 %Pawnee County: 77.6 %Payne County: 56.7 %Pittsburg County: 60.4 %Seminole County: 60.3 %Tulsa County: 30.1 %
  • Under 60
  • 60 to 65
  • 65 to 72
  • 72 to 74
  • 74 and over
  • No data
Share of days with good air quality (US EPA AQI), 2002, %. Marshall 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), Marshall County, 1999 to 2002) [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), Marshall County, 1999 to 2002. 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/marshall-county-oklahoma. 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), Marshall County, 1999 to 2002. 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/marshall-county-oklahoma.

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), Marshall County, 1999 to 2002 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/good-air-quality-days-share/marshall-county-oklahoma (Accessed: 12 October 2026).

BibTeX
@misc{environmental_share_of_days_with_2002,
  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), Marshall County, 1999 to 2002}},
  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/marshall-county-oklahoma. 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), Marshall County, 1999 to 2002
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/marshall-county-oklahoma
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/good-air-quality-days-share/marshall-county-oklahoma.
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 Marshall County?

Share of days with good air quality (US EPA AQI) in Marshall County was 68.7% in 2002, according to EPA. That is up 5.6 pts from 2001.

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 Marshall County?

68.7% in 2002, the highest value since 1999 in this series.

Related statistics for Marshall County

All statistics for Marshall County | Marshall County in figures