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

Median Air Quality Index (US EPA) in DeKalb County

Median Air Quality Index (US EPA) in DeKalb County was 41 in 2025, according to the U.S. Environmental Protection Agency. That is down 2 from 2024.

2025, index41
Change on 2024-2
Series high611999
Series low362018

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 DeKalb County, 1990 to 2025

3540455055606519901996200220082014202020251990: 47 index1991: 41 index1992: 38 index1993: 44 index1994: 38 index1995: 48 index1996: 41 index1997: 37 index1998: 46 index1999: 61 index2000: 54 index2001: 47 index2002: 45 index2003: 47 index2004: 44 index2005: 44 index2006: 49 index2007: 49 index2008: 44 index2009: 38 index2010: 44 index2011: 42 index2012: 42 index2013: 40 index2014: 40 index2015: 38 index2016: 41 index2017: 40 index2018: 36 index2019: 39 index2020: 37 index2021: 37 index2022: 38 index2023: 48 index2024: 43 index2025: 41 index304050607019902002201420251990: 47 index1991: 41 index1992: 38 index1993: 44 index1994: 38 index1995: 48 index1996: 41 index1997: 37 index1998: 46 index1999: 61 index2000: 54 index2001: 47 index2002: 45 index2003: 47 index2004: 44 index2005: 44 index2006: 49 index2007: 49 index2008: 44 index2009: 38 index2010: 44 index2011: 42 index2012: 42 index2013: 40 index2014: 40 index2015: 38 index2016: 41 index2017: 40 index2018: 36 index2019: 39 index2020: 37 index2021: 37 index2022: 38 index2023: 48 index2024: 43 index2025: 41 index
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 36 values
Periodindex
202541
202443
202348
202238
202137
202037
201939
201836
201740
201641
201538
201440
201340
201242
201142
201044
200938
200844
200749
200649
200544
200444
200347
200245
200147
200054
199961
199846
199737
199641
199548
199438
199344
199238
199141
199047

DeKalb County compared with nearby places

Baldwin County: 42 indexClay County: 33 indexDeKalb County: 41 indexElmore County: 34 indexEtowah County: 45 indexJefferson County: 52 indexLawrence County: 30 indexMadison County: 42 indexMobile County: 43 indexMontgomery County: 44 indexMorgan County: 41 indexRussell County: 40 indexShelby County: 36 indexSumter County: 41 indexTuscaloosa County: 41 index
  • Under 36
  • 36 to 41
  • 41 to 43
  • 43 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. DeKalb 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), DeKalb 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: median daily AQI, Median Air Quality Index (US EPA), DeKalb 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/median-air-quality-index/dekalb-county-alabama. 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), DeKalb 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/median-air-quality-index/dekalb-county-alabama.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Median Air Quality Index (US EPA), DeKalb County, 1990 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/dekalb-county-alabama (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), DeKalb 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/median-air-quality-index/dekalb-county-alabama. 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), DeKalb 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/median-air-quality-index/dekalb-county-alabama
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/median-air-quality-index/dekalb-county-alabama.
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 DeKalb County?

Median Air Quality Index (US EPA) in DeKalb County was 41 in 2025, according to the U.S. Environmental Protection Agency. That is down 2 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 DeKalb County?

61 in 1999, the highest value since 1990 in this series.

Related statistics for DeKalb County

All statistics for DeKalb County | DeKalb County in figures