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

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

Share of days with good air quality (US EPA AQI) in San Francisco County was 76% in 2024, according to EPA. That is down 5.9 pts from 2023. That is the 15th highest of 52 counties in 2024.

202476%
Change on 2023-5.9 pts
Rank15th of 52Counties in California ranked
Series high971998
Series low312009

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.

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

2040608010019801987199420012008201520241980: 76.5 %1981: 77.3 %1982: 74.2 %1983: 73.7 %1984: 69.9 %1985: 71.5 %1986: 72.6 %1987: 81.6 %1988: 77.3 %1989: 77.5 %1990: 84.4 %1991: 80.3 %1992: 91 %1993: 86.6 %1994: 88.2 %1995: 91.2 %1996: 92.1 %1997: 93.2 %1998: 97 %1999: 72.9 %2000: 66.9 %2001: 68.2 %2002: 67.1 %2003: 70.4 %2004: 46.7 %2005: 63.6 %2006: 59.2 %2007: 58.1 %2008: 42.6 %2009: 31 %2010: 46.8 %2011: 52.1 %2012: 65.4 %2013: 52.9 %2014: 68.2 %2015: 67.4 %2016: 64.5 %2017: 57.8 %2018: 60.8 %2019: 68.8 %2020: 62 %2021: 69.9 %2022: 71.4 %2023: 81.9 %2024: 76 %
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12, published 2026-07-13.
All 45 values
Period%
202476
202381.9
202271.4
202169.9
202062
201968.8
201860.8
201757.8
201664.5
201567.4
201468.2
201352.9
201265.4
201152.1
201046.8
200931
200842.6
200758.1
200659.2
200563.6
200446.7
200370.4
200267.1
200168.2
200066.9
199972.9
199897
199793.2
199692.1
199591.2
199488.2
199386.6
199291
199180.3
199084.4
198977.5
198877.3
198781.6
198672.6
198571.5
198469.9
198373.7
198274.2
198177.3
198076.5

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.

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), San Francisco 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), San Francisco 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/san-francisco-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), San Francisco 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/san-francisco-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), San Francisco 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/san-francisco-county-california (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), San Francisco 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/san-francisco-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), San Francisco 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/san-francisco-county-california
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/good-air-quality-days-share/san-francisco-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  -
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 San Francisco County? Cite the source.
get_value {"indicator":"aqi_good_days_share","place":"us-county-06075"}
GET https://invokely.ai/api/v1/value?indicator=aqi_good_days_share&place=us-county-06075

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 San Francisco County?

Share of days with good air quality (US EPA AQI) in San Francisco County was 76% in 2024, according to EPA. That is down 5.9 pts from 2023. That is the 15th highest of 52 counties in 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 San Francisco County?

97% in 1998, the highest value since 1980 in this series.

Related statistics for San Francisco County

All statistics for San Francisco County | San Francisco County in figures