Data / Highest daily Air Quality Index (US EPA) / Montgomery County

Highest daily Air Quality Index (US EPA) in Montgomery County

Highest daily Air Quality Index (US EPA) in Montgomery County was 133 in 2025, according to the U.S. Environmental Protection Agency. That is up 53 from 2024.

2025, index133
Change on 2024+53
Series high1472023
Series low772019

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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Highest daily Air Quality Index (US EPA) in Montgomery County, 2002 to 2025

608010012014016020022006201020142018202220252002: 126 index2003: 119 index2004: 94 index2005: 121 index2006: 119 index2007: 108 index2008: 84 index2009: 133 index2010: 112 index2011: 93 index2012: 112 index2013: 133 index2014: 107 index2015: 97 index2016: 121 index2017: 84 index2018: 93 index2019: 77 index2020: 79 index2021: 112 index2022: 79 index2023: 147 index2024: 80 index2025: 133 index608010012014016020022010201820252002: 126 index2003: 119 index2004: 94 index2005: 121 index2006: 119 index2007: 108 index2008: 84 index2009: 133 index2010: 112 index2011: 93 index2012: 112 index2013: 133 index2014: 107 index2015: 97 index2016: 121 index2017: 84 index2018: 93 index2019: 77 index2020: 79 index2021: 112 index2022: 79 index2023: 147 index2024: 80 index2025: 133 index
index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 24 values
Periodindex
2025133
202480
2023147
202279
2021112
202079
201977
201893
201784
2016121
201597
2014107
2013133
2012112
201193
2010112
2009133
200884
2007108
2006119
2005121
200494
2003119
2002126

Montgomery County compared with nearby places

Black Hawk County: 158 indexBremer County: 115 indexClinton County: 166 indexHarrison County: 119 indexJohnson County: 159 indexLinn County: 163 indexMontgomery County: 133 indexMuscatine County: 141 indexPalo Alto County: 134 indexPolk County: 136 indexPottawattamie County: 87 indexScott County: 159 indexVan Buren County: 129 indexWebster County: 165 indexWoodbury County: 122 index
  • Under 120
  • 120 to 130
  • 130 to 150
  • 150 to 160
  • 160 and over
  • No data
Highest daily Air Quality Index (US EPA), 2025, index. Montgomery 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

Highest daily Air Quality Index (AQI) value recorded in a US county during the year, from the EPA AirData annual summaries. Values above 500 are beyond the AQI scale and are published as EPA computes them.

A single day decides the value, so one wildfire or dust event can set it. Dust from the dry Owens Lake bed puts Inyo and Mono counties in California in the thousands. 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: highest 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: highest daily AQI (Highest daily Air Quality Index (US EPA), Montgomery County, 2002 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: highest daily AQI, Highest daily Air Quality Index (US EPA), Montgomery County, 2002 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/highest-daily-air-quality-index/montgomery-county-iowa. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Highest daily Air Quality Index (US EPA), Montgomery County, 2002 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/highest-daily-air-quality-index/montgomery-county-iowa.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Highest daily Air Quality Index (US EPA), Montgomery County, 2002 to 2025 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/highest-daily-air-quality-index/montgomery-county-iowa (Accessed: 12 October 2026).

BibTeX
@misc{environmental_highest_daily_air_quality_2025,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Highest daily Air Quality Index (US EPA), Montgomery County, 2002 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/highest-daily-air-quality-index/montgomery-county-iowa. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest 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: highest daily AQI: Highest daily Air Quality Index (US EPA), Montgomery County, 2002 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/highest-daily-air-quality-index/montgomery-county-iowa
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/highest-daily-air-quality-index/montgomery-county-iowa.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest 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 highest daily Air Quality Index (US EPA) in Montgomery County?

Highest daily Air Quality Index (US EPA) in Montgomery County was 133 in 2025, according to the U.S. Environmental Protection Agency. That is up 53 from 2024.

Where does this figure come from?

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

What was the highest highest daily Air Quality Index (US EPA) in Montgomery County?

147 in 2023, the highest value since 2002 in this series.

Related statistics for Montgomery County

All statistics for Montgomery County | Montgomery County in figures