Data / Median Air Quality Index (US EPA) / Chittenden County

Median Air Quality Index (US EPA) in Chittenden County

Median Air Quality Index (US EPA) in Chittenden County was 38 in 2025, according to the U.S. Environmental Protection Agency. That is up 1 from 2024.

2025, index38
Change on 2024+1
Series high432011
Series low201980

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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Median Air Quality Index (US EPA) in Chittenden County, 1980 to 2025

20253035404519801987199420012008201520251980: 20 index1981: 23 index1982: 25 index1983: 27 index1984: 31 index1985: 31 index1986: 34 index1987: 36 index1988: 34 index1989: 36 index1990: 34 index1991: 34 index1992: 33 index1993: 33 index1994: 37 index1995: 35 index1996: 34 index1997: 34 index1998: 35 index1999: 38 index2000: 36 index2001: 41 index2002: 38 index2003: 38 index2004: 37 index2005: 41 index2006: 36 index2007: 35 index2008: 42 index2009: 41 index2010: 41 index2011: 43 index2012: 37 index2013: 42 index2014: 41 index2015: 39 index2016: 36 index2017: 37 index2018: 40 index2019: 39 index2020: 39 index2021: 40 index2022: 41 index2023: 42 index2024: 37 index2025: 38 index2030405019801996201220251980: 20 index1981: 23 index1982: 25 index1983: 27 index1984: 31 index1985: 31 index1986: 34 index1987: 36 index1988: 34 index1989: 36 index1990: 34 index1991: 34 index1992: 33 index1993: 33 index1994: 37 index1995: 35 index1996: 34 index1997: 34 index1998: 35 index1999: 38 index2000: 36 index2001: 41 index2002: 38 index2003: 38 index2004: 37 index2005: 41 index2006: 36 index2007: 35 index2008: 42 index2009: 41 index2010: 41 index2011: 43 index2012: 37 index2013: 42 index2014: 41 index2015: 39 index2016: 36 index2017: 37 index2018: 40 index2019: 39 index2020: 39 index2021: 40 index2022: 41 index2023: 42 index2024: 37 index2025: 38 index
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 46 values
Periodindex
202538
202437
202342
202241
202140
202039
201939
201840
201737
201636
201539
201441
201342
201237
201143
201041
200941
200842
200735
200636
200541
200437
200338
200238
200141
200036
199938
199835
199734
199634
199535
199437
199333
199233
199134
199034
198936
198834
198736
198634
198531
198431
198327
198225
198123
198020

Chittenden County compared with nearby places

Bennington County: 37 indexChittenden County: 38 indexRutland County: 37 indexWindham County: 15 index
  • Under 37
  • 37 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. Chittenden 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

Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries.

More on how it is measured
  • The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide).
  • Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.

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: median daily AQI. 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: median daily AQI (Median Air Quality Index (US EPA), Chittenden 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: median daily AQI, Median Air Quality Index (US EPA), Chittenden 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/median-air-quality-index/chittenden-county-vermont. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Median Air Quality Index (US EPA), Chittenden 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/median-air-quality-index/chittenden-county-vermont.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Median Air Quality Index (US EPA), Chittenden County, 1980 to 2025 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/median-air-quality-index/chittenden-county-vermont (Accessed: 12 October 2026).

BibTeX
@misc{environmental_median_air_quality_index_2025,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Median Air Quality Index (US EPA), Chittenden 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/median-air-quality-index/chittenden-county-vermont. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. 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: median daily AQI: Median Air Quality Index (US EPA), Chittenden 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/median-air-quality-index/chittenden-county-vermont
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/median-air-quality-index/chittenden-county-vermont.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Questions

What is the median Air Quality Index (US EPA) in Chittenden County?

Median Air Quality Index (US EPA) in Chittenden County was 38 in 2025, according to the U.S. Environmental Protection Agency. That is up 1 from 2024.

Where does this figure come from?

U.S. Environmental Protection Agency. EPA AirData annual AQI by county: median daily AQI. Retrieved by Invokely on 2026-10-12.

What was the highest median Air Quality Index (US EPA) in Chittenden County?

43 in 2011, the highest value since 1980 in this series.

Related statistics for Chittenden County

All statistics for Chittenden County | Chittenden County in figures