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

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

Share of days with good air quality (US EPA AQI) in Cascade County was 59.8% in 2024, according to EPA. That is up 9.7 pts from 2023.

202459.8%
Change on 2023+9.7 pts
Series high1001999
Series low50.12023

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

Get an email when a new figure is out or this one is revised.
Keep it in a collection in your library.

Share of days with good air quality (US EPA AQI) in Cascade County, 1980 to 2024

506070809010019801987199420012008201520241980: 84.7 %1981: 90.2 %1982: 99.6 %1983: 89.1 %1984: 91.6 %1985: 90.2 %1986: 86.3 %1987: 87.5 %1988: 84.6 %1989: 92.5 %1990: 97.1 %1991: 94.1 %1992: 96.3 %1993: 95.9 %1994: 98.1 %1995: 96.8 %1996: 98.8 %1997: 98.1 %1998: 99.4 %1999: 100 %2000: 93.4 %2001: 95.5 %2002: 96.5 %2003: 93.2 %2004: 97.8 %2005: 93.2 %2006: 94 %2007: 94 %2008: 87.9 %2009: 62.7 %2010: 71.2 %2011: 65.4 %2012: 64.2 %2013: 77.7 %2014: 67.3 %2015: 78.1 %2016: 89.6 %2017: 69.9 %2018: 84.2 %2019: 89.8 %2020: 87.5 %2021: 81.1 %2022: 90 %2023: 50.1 %2024: 59.8 %40608010019801995201020241980: 84.7 %1981: 90.2 %1982: 99.6 %1983: 89.1 %1984: 91.6 %1985: 90.2 %1986: 86.3 %1987: 87.5 %1988: 84.6 %1989: 92.5 %1990: 97.1 %1991: 94.1 %1992: 96.3 %1993: 95.9 %1994: 98.1 %1995: 96.8 %1996: 98.8 %1997: 98.1 %1998: 99.4 %1999: 100 %2000: 93.4 %2001: 95.5 %2002: 96.5 %2003: 93.2 %2004: 97.8 %2005: 93.2 %2006: 94 %2007: 94 %2008: 87.9 %2009: 62.7 %2010: 71.2 %2011: 65.4 %2012: 64.2 %2013: 77.7 %2014: 67.3 %2015: 78.1 %2016: 89.6 %2017: 69.9 %2018: 84.2 %2019: 89.8 %2020: 87.5 %2021: 81.1 %2022: 90 %2023: 50.1 %2024: 59.8 %
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12, published 2026-07-13.
All 45 values
Period%
202459.8
202350.1
202290
202181.1
202087.5
201989.8
201884.2
201769.9
201689.6
201578.1
201467.3
201377.7
201264.2
201165.4
201071.2
200962.7
200887.9
200794
200694
200593.2
200497.8
200393.2
200296.5
200195.5
200093.4
1999100
199899.4
199798.1
199698.8
199596.8
199498.1
199395.9
199296.3
199194.1
199097.1
198992.5
198884.6
198787.5
198686.3
198590.2
198491.6
198389.1
198299.6
198190.2
198084.7

Cascade County compared with nearby places

Beaverhead County: 86.1 %Cascade County: 59.8 %Custer County: 90.9 %Dawson County: 89.9 %Fergus County: 85.2 %Flathead County: 69.1 %Gallatin County: 90.1 %Glacier County: 88.4 %Hill County: 92.6 %Lake County: 93.9 %Lewis and Clark County: 63.7 %Lincoln County: 50.7 %Missoula County: 64.8 %Phillips County: 89.2 %Powell County: 88.6 %Ravalli County: 70.2 %Richland County: 83.9 %Roosevelt County: 88.8 %Rosebud County: 96.4 %Sanders County: 93.1 %Sheridan County: 87.4 %Silver Bow County: 70.5 %Teton County: 92.3 %Yellowstone County: 76.2 %
  • Under 70
  • 70 to 85
  • 85 to 89
  • 89 to 91
  • 91 and over
  • No data
Share of days with good air quality (US EPA AQI), 2024, %. Cascade 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.

Report a problem with this figure

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), Cascade County, 1980 to 2024) [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), Cascade County, 1980 to 2024. 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/cascade-county-montana. 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), Cascade County, 1980 to 2024. 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/cascade-county-montana.

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), Cascade County, 1980 to 2024 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/good-air-quality-days-share/cascade-county-montana (Accessed: 12 October 2026).

BibTeX
@misc{environmental_share_of_days_with_2024,
  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), Cascade County, 1980 to 2024}},
  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/cascade-county-montana. 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), Cascade County, 1980 to 2024
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/cascade-county-montana
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/good-air-quality-days-share/cascade-county-montana.
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  -
Embed this chart

Paste this code into a web page or a blog post. The chart shows the latest figures as they are published, with the source and a link back to this page.

Sites that read oEmbed links, such as WordPress, can show the chart when you paste the link to this page.

Use this data in your AI agent

Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:

What is the latest share of days with good air quality (US EPA AQI) in Cascade County? Cite the source.
get_value {"indicator":"aqi_good_days_share","place":"us-county-30013"}
GET https://invokely.ai/api/v1/value?indicator=aqi_good_days_share&place=us-county-30013

Connect Claude, ChatGPT or Cursor in one step. The trial answers 25 calls a day without an account.

Questions

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

Share of days with good air quality (US EPA AQI) in Cascade County was 59.8% in 2024, according to EPA. That is up 9.7 pts from 2023.

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 Cascade County?

100% in 1999, the highest value since 1980 in this series.

Related statistics for Cascade County

All statistics for Cascade County | Cascade County in figures