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

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

Share of days with good air quality (US EPA AQI) in Nevada County was 79.8% in 2025, according to EPA. That is down 6 pts from 2024.

202579.8%
Change on 2024-6 pts
Series high93.41993
Series low23.62007

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 Nevada County, 1990 to 2025

2040608010019901996200220082014202020251990: 58.9 %1991: 62.3 %1992: 66.2 %1993: 93.4 %1994: 64.6 %1995: 64 %1996: 54.1 %1997: 27.1 %1998: 51.2 %1999: 35.3 %2000: 41.5 %2001: 42.7 %2002: 45.8 %2003: 44.7 %2004: 44 %2005: 49.6 %2006: 45.5 %2007: 23.6 %2008: 47.3 %2009: 63.7 %2010: 66.3 %2011: 63.8 %2012: 61.7 %2013: 55.8 %2014: 57.8 %2015: 58.5 %2016: 63.4 %2017: 53.2 %2018: 63.6 %2019: 69.5 %2020: 60.9 %2021: 50.1 %2022: 50.7 %2023: 77.7 %2024: 85.8 %2025: 79.8 %2040608010019902002201420251990: 58.9 %1991: 62.3 %1992: 66.2 %1993: 93.4 %1994: 64.6 %1995: 64 %1996: 54.1 %1997: 27.1 %1998: 51.2 %1999: 35.3 %2000: 41.5 %2001: 42.7 %2002: 45.8 %2003: 44.7 %2004: 44 %2005: 49.6 %2006: 45.5 %2007: 23.6 %2008: 47.3 %2009: 63.7 %2010: 66.3 %2011: 63.8 %2012: 61.7 %2013: 55.8 %2014: 57.8 %2015: 58.5 %2016: 63.4 %2017: 53.2 %2018: 63.6 %2019: 69.5 %2020: 60.9 %2021: 50.1 %2022: 50.7 %2023: 77.7 %2024: 85.8 %2025: 79.8 %
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12, published 2026-07-13.
All 36 values
Period%
202579.8
202485.8
202377.7
202250.7
202150.1
202060.9
201969.5
201863.6
201753.2
201663.4
201558.5
201457.8
201355.8
201261.7
201163.8
201066.3
200963.7
200847.3
200723.6
200645.5
200549.6
200444
200344.7
200245.8
200142.7
200041.5
199935.3
199851.2
199727.1
199654.1
199564
199464.6
199393.4
199266.2
199162.3
199058.9

Nevada County compared with nearby places

Amador County: 87.4 %Butte County: 65.2 %Calaveras County: 82.2 %Colusa County: 79.2 %Del Norte County: 81.8 %El Dorado County: 87.7 %Fresno County: 28.8 %Glenn County: 80 %Humboldt County: 78.1 %Imperial County: 27.7 %Inyo County: 37.3 %Kern County: 17.5 %Kings County: 34.5 %Lake County: 99.2 %Los Angeles County: 10.7 %Madera County: 50.4 %Marin County: 91.6 %Mariposa County: 80.6 %Mendocino County: 73.7 %Merced County: 51 %Mono County: 90.1 %Monterey County: 86 %Nevada County: 79.8 %Orange County: 37.8 %Placer County: 45.8 %Plumas County: 52.9 %Riverside County: 10.7 %Sacramento County: 54.2 %San Benito County: 91.5 %San Bernardino County: 12.6 %San Diego County: 17.5 %San Joaquin County: 60 %San Luis Obispo County: 52.3 %Santa Barbara County: 44.9 %Santa Cruz County: 87.7 %Shasta County: 75.6 %Siskiyou County: 78.2 %Solano County: 99.2 %Sonoma County: 100 %Stanislaus County: 49.9 %Sutter County: 63.2 %Tehama County: 77.8 %Trinity County: 69.6 %Tulare County: 24.1 %Tuolumne County: 87 %Ventura County: 52.1 %Yolo County: 58.4 %
  • Under 33
  • 33 to 51
  • 51 to 65
  • 65 to 80
  • 80 to 88
  • 88 and over
  • No data
Share of days with good air quality (US EPA AQI), 2025, %. Nevada 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), Nevada County, 1990 to 2025) [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), Nevada County, 1990 to 2025. 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/nevada-county-california. 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), Nevada County, 1990 to 2025. 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/nevada-county-california.

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), Nevada County, 1990 to 2025 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/good-air-quality-days-share/nevada-county-california (Accessed: 12 October 2026).

BibTeX
@misc{environmental_share_of_days_with_2025,
  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), Nevada County, 1990 to 2025}},
  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/nevada-county-california. 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), Nevada County, 1990 to 2025
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/nevada-county-california
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/good-air-quality-days-share/nevada-county-california.
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 Nevada County?

Share of days with good air quality (US EPA AQI) in Nevada County was 79.8% in 2025, according to EPA. That is down 6 pts from 2024.

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 Nevada County?

93.4% in 1993, the highest value since 1990 in this series.

Related statistics for Nevada County

All statistics for Nevada County | Nevada County in figures