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

Median Air Quality Index (US EPA) in Delaware County

Median Air Quality Index (US EPA) in Delaware County was 29 in 2017, according to the U.S. Environmental Protection Agency. That is down 2 from 2016.

2017, index29
Change on 2016-2
Series high522007
Series low121990

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 Delaware County, 1987 to 2017

10203040506019871992199720022007201220171987: 16 index1988: 17 index1989: 16 index1990: 12 index1991: 16 index1992: 16 index1993: 16 index1994: 17 index1995: 20 index1996: 18 index1997: 18 index1998: 17 index1999: 15 index2000: 15 index2001: 14 index2002: 14 index2003: 14 index2004: 12 index2005: 14 index2006: 15 index2007: 52 index2008: 51 index2009: 14 index2010: 15 index2011: 48 index2012: 42 index2013: 46 index2014: 43 index2015: 38 index2016: 31 index2017: 29 index1020304050601987199820171987: 16 index1988: 17 index1989: 16 index1990: 12 index1991: 16 index1992: 16 index1993: 16 index1994: 17 index1995: 20 index1996: 18 index1997: 18 index1998: 17 index1999: 15 index2000: 15 index2001: 14 index2002: 14 index2003: 14 index2004: 12 index2005: 14 index2006: 15 index2007: 52 index2008: 51 index2009: 14 index2010: 15 index2011: 48 index2012: 42 index2013: 46 index2014: 43 index2015: 38 index2016: 31 index2017: 29 index
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 31 values
Periodindex
201729
201631
201538
201443
201346
201242
201148
201015
200914
200851
200752
200615
200514
200412
200314
200214
200114
200015
199915
199817
199718
199618
199520
199417
199316
199216
199116
199012
198916
198817
198716

Delaware County compared with nearby places

Black Hawk County: 54 indexBremer County: 36 indexCerro Gordo County: 15 indexClinton County: 58 indexDelaware County: 29 indexHarrison County: 39 indexJohnson County: 44 indexLee County: 43 indexLinn County: 45 indexMontgomery County: 45 indexMuscatine County: 51 indexPalo Alto County: 49 indexPolk County: 45 indexPottawattamie County: 43 indexScott County: 56 indexVan Buren County: 47 indexWarren County: 39 indexWoodbury County: 37 index
  • Under 38
  • 38 to 43
  • 43 to 45
  • 45 to 50
  • 50 and over
  • No data
Median Air Quality Index (US EPA), 2017, index. Delaware 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), Delaware County, 1987 to 2017) [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), Delaware County, 1987 to 2017. 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/delaware-county-iowa. 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), Delaware County, 1987 to 2017. 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/delaware-county-iowa.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Median Air Quality Index (US EPA), Delaware County, 1987 to 2017 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/median-air-quality-index/delaware-county-iowa (Accessed: 12 October 2026).

BibTeX
@misc{environmental_median_air_quality_index_2017,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Median Air Quality Index (US EPA), Delaware County, 1987 to 2017}},
  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/delaware-county-iowa. 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), Delaware County, 1987 to 2017
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/delaware-county-iowa
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/median-air-quality-index/delaware-county-iowa.
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 Delaware County?

Median Air Quality Index (US EPA) in Delaware County was 29 in 2017, according to the U.S. Environmental Protection Agency. That is down 2 from 2016.

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 Delaware County?

52 in 2007, the highest value since 1987 in this series.

Related statistics for Delaware County

All statistics for Delaware County | Delaware County in figures