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

Median Air Quality Index (US EPA) in Baltimore County

Median Air Quality Index (US EPA) in Baltimore County was 45 in 2025, according to the U.S. Environmental Protection Agency. That is unchanged from 2024. That is the 1st highest of 16 counties in 2025.

2025, index45
Change on 20240
Rank1st of 16Counties in Maryland ranked
Series high612001
Series low341996

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 Baltimore County, 1980 to 2025

304050607019801987199420012008201520251980: 44 index1981: 47 index1982: 50 index1983: 50 index1984: 44 index1985: 50 index1986: 48 index1987: 51 index1988: 47 index1989: 44 index1990: 45 index1991: 46 index1992: 42 index1993: 43 index1994: 45 index1995: 39 index1996: 34 index1997: 36 index1998: 42 index1999: 44 index2000: 55 index2001: 61 index2002: 61 index2003: 58 index2004: 59 index2005: 61 index2006: 60 index2007: 58 index2008: 56 index2009: 54 index2010: 46 index2011: 43 index2012: 44 index2013: 41 index2014: 42 index2015: 43 index2016: 48 index2017: 43 index2018: 46 index2019: 46 index2020: 43 index2021: 47 index2022: 45 index2023: 45 index2024: 45 index2025: 45 index304050607019801996201220251980: 44 index1981: 47 index1982: 50 index1983: 50 index1984: 44 index1985: 50 index1986: 48 index1987: 51 index1988: 47 index1989: 44 index1990: 45 index1991: 46 index1992: 42 index1993: 43 index1994: 45 index1995: 39 index1996: 34 index1997: 36 index1998: 42 index1999: 44 index2000: 55 index2001: 61 index2002: 61 index2003: 58 index2004: 59 index2005: 61 index2006: 60 index2007: 58 index2008: 56 index2009: 54 index2010: 46 index2011: 43 index2012: 44 index2013: 41 index2014: 42 index2015: 43 index2016: 48 index2017: 43 index2018: 46 index2019: 46 index2020: 43 index2021: 47 index2022: 45 index2023: 45 index2024: 45 index2025: 45 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
202545
202445
202345
202245
202147
202043
201946
201846
201743
201648
201543
201442
201341
201244
201143
201046
200954
200856
200758
200660
200561
200459
200358
200261
200161
200055
199944
199842
199736
199634
199539
199445
199343
199242
199146
199045
198944
198847
198751
198648
198550
198444
198350
198250
198147
198044

Baltimore County compared with nearby places

Anne Arundel County: 40 indexBaltimore County: 45 indexCalvert County: 38 indexCarroll County: 38 indexCecil County: 41 indexCharles County: 38 indexDorchester County: 39 indexFrederick County: 41 indexGarrett County: 39 indexHarford County: 42 indexHoward County: 33 indexKent County: 38 indexMontgomery County: 39 indexPrince George's County: 40 indexWashington County: 40 indexBaltimore city: 43 index
  • Under 38
  • 38 to 39
  • 39 to 40
  • 40 to 41
  • 41 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. Baltimore 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), Baltimore 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), Baltimore 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/baltimore-county-maryland. 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), Baltimore 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/baltimore-county-maryland.

Harvard

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

Median Air Quality Index (US EPA) in Baltimore County was 45 in 2025, according to the U.S. Environmental Protection Agency. That is unchanged from 2024. That is the 1st highest of 16 counties in 2025.

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 Baltimore County?

61 in 2001, the highest value since 1980 in this series.

Related statistics for Baltimore County

All statistics for Baltimore County | Baltimore County in figures