Data / Share of days unhealthy for sensitive groups or worse (US EPA AQI) / Multnomah County

Share of days unhealthy for sensitive groups or worse (US EPA AQI) in Multnomah County

Share of days unhealthy for sensitive groups or worse (US EPA AQI) in Multnomah County was 0% in 2025, according to EPA. That is unchanged from 2024.

20250%
Change on 20240 pts
Series high6.61981
Series low01990

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 unhealthy for sensitive groups or worse (US EPA AQI) in Multnomah County, 1980 to 2025

0246819801987199420012008201520251980: 5.2 %1981: 6.6 %1982: 1.9 %1983: 3.8 %1984: 0.8 %1985: 0.5 %1986: 2.2 %1987: 1.1 %1988: 0.8 %1989: 1.4 %1990: 0 %1991: 1.1 %1992: 0 %1993: 0 %1994: 0 %1995: 0 %1996: 0 %1997: 0 %1998: 0 %1999: 1.6 %2000: 1.4 %2001: 1.1 %2002: 0.8 %2003: 0 %2004: 2.2 %2005: 1.4 %2006: 1.9 %2007: 2.2 %2008: 1.4 %2009: 0.8 %2010: 0 %2011: 1.6 %2012: 0.3 %2013: 1.4 %2014: 0.3 %2015: 0.5 %2016: 0.3 %2017: 1.6 %2018: 2.5 %2019: 0 %2020: 2.5 %2021: 0.3 %2022: 1.4 %2023: 0.3 %2024: 0 %2025: 0 %0246819801996201220251980: 5.2 %1981: 6.6 %1982: 1.9 %1983: 3.8 %1984: 0.8 %1985: 0.5 %1986: 2.2 %1987: 1.1 %1988: 0.8 %1989: 1.4 %1990: 0 %1991: 1.1 %1992: 0 %1993: 0 %1994: 0 %1995: 0 %1996: 0 %1997: 0 %1998: 0 %1999: 1.6 %2000: 1.4 %2001: 1.1 %2002: 0.8 %2003: 0 %2004: 2.2 %2005: 1.4 %2006: 1.9 %2007: 2.2 %2008: 1.4 %2009: 0.8 %2010: 0 %2011: 1.6 %2012: 0.3 %2013: 1.4 %2014: 0.3 %2015: 0.5 %2016: 0.3 %2017: 1.6 %2018: 2.5 %2019: 0 %2020: 2.5 %2021: 0.3 %2022: 1.4 %2023: 0.3 %2024: 0 %2025: 0 %
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12, published 2026-07-13.
All 46 values
Period%
20250
20240
20230.3
20221.4
20210.3
20202.5
20190
20182.5
20171.6
20160.3
20150.5
20140.3
20131.4
20120.3
20111.6
20100
20090.8
20081.4
20072.2
20061.9
20051.4
20042.2
20030
20020.8
20011.1
20001.4
19991.6
19980
19970
19960
19950
19940
19930
19920
19911.1
19900
19891.4
19880.8
19871.1
19862.2
19850.5
19840.8
19833.8
19821.9
19816.6
19805.2

Multnomah County compared with nearby places

Baker County: 0 %Clackamas County: 0.6 %Columbia County: 0 %Crook County: 0.5 %Deschutes County: 0.8 %Grant County: 0 %Harney County: 0 %Jackson County: 0.5 %Jefferson County: 0 %Josephine County: 2.2 %Klamath County: 0.8 %Lake County: 0.3 %Lane County: 1.6 %Linn County: 0.3 %Marion County: 0 %Multnomah County: 0 %Umatilla County: 0 %Union County: 0 %Wallowa County: 0 %Wasco County: 0 %Washington County: 0 %
  • Under 0.3
  • 0.3 to 0.6
  • 0.6 and over
  • No data
Share of days unhealthy for sensitive groups or worse (US EPA AQI), 2025, %. Multnomah 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 above 100 (unhealthy for sensitive groups, unhealthy, very unhealthy or hazardous) 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; the counts are stored with each value.

Use the share rather than the number of days to compare counties, since the days with an AQI differ. 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: days with an AQI above 100 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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts (Share of days unhealthy for sensitive groups or worse (US EPA AQI), Multnomah County, 1980 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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts, Share of days unhealthy for sensitive groups or worse (US EPA AQI), Multnomah County, 1980 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/unhealthy-air-quality-days-share/multnomah-county-oregon. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts. Share of days unhealthy for sensitive groups or worse (US EPA AQI), Multnomah County, 1980 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/unhealthy-air-quality-days-share/multnomah-county-oregon.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts, Share of days unhealthy for sensitive groups or worse (US EPA AQI), Multnomah County, 1980 to 2025 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/unhealthy-air-quality-days-share/multnomah-county-oregon (Accessed: 12 October 2026).

BibTeX
@misc{environmental_share_of_days_unhealthy_2025,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts: Share of days unhealthy for sensitive groups or worse (US EPA AQI), Multnomah County, 1980 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/unhealthy-air-quality-days-share/multnomah-county-oregon. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: days with an AQI above 100 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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts: Share of days unhealthy for sensitive groups or worse (US EPA AQI), Multnomah County, 1980 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/unhealthy-air-quality-days-share/multnomah-county-oregon
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/unhealthy-air-quality-days-share/multnomah-county-oregon.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: days with an AQI above 100 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 unhealthy for sensitive groups or worse (US EPA AQI) in Multnomah County?

Share of days unhealthy for sensitive groups or worse (US EPA AQI) in Multnomah County was 0% in 2025, according to EPA. That is unchanged from 2024.

Where does this figure come from?

U.S. Environmental Protection Agency. EPA AirData annual AQI by county: days with an AQI above 100 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 unhealthy for sensitive groups or worse (US EPA AQI) in Multnomah County?

6.6% in 1981, the highest value since 1980 in this series.

Related statistics for Multnomah County

All statistics for Multnomah County | Multnomah County in figures