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

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

Highest daily Air Quality Index (US EPA) in Delaware County was 70 in 2017, according to the U.S. Environmental Protection Agency. That is down 11 from 2016.

2017, index70
Change on 2016-11
Series high1402007
Series low351991

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 Delaware County, 1987 to 2017

25507510012515019871992199720022007201220171987: 46 index1988: 69 index1989: 56 index1990: 95 index1991: 35 index1992: 40 index1993: 46 index1994: 39 index1995: 38 index1996: 51 index1997: 48 index1998: 52 index1999: 36 index2000: 46 index2001: 42 index2002: 39 index2003: 35 index2004: 36 index2005: 44 index2006: 45 index2007: 140 index2008: 104 index2009: 44 index2010: 53 index2011: 86 index2012: 79 index2013: 90 index2014: 80 index2015: 76 index2016: 81 index2017: 70 index0501001501987199820171987: 46 index1988: 69 index1989: 56 index1990: 95 index1991: 35 index1992: 40 index1993: 46 index1994: 39 index1995: 38 index1996: 51 index1997: 48 index1998: 52 index1999: 36 index2000: 46 index2001: 42 index2002: 39 index2003: 35 index2004: 36 index2005: 44 index2006: 45 index2007: 140 index2008: 104 index2009: 44 index2010: 53 index2011: 86 index2012: 79 index2013: 90 index2014: 80 index2015: 76 index2016: 81 index2017: 70 index
index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 31 values
Periodindex
201770
201681
201576
201480
201390
201279
201186
201053
200944
2008104
2007140
200645
200544
200436
200335
200239
200142
200046
199936
199852
199748
199651
199538
199439
199346
199240
199135
199095
198956
198869
198746

Delaware County compared with nearby places

Black Hawk County: 84 indexBremer County: 93 indexCerro Gordo County: 65 indexClinton County: 93 indexDelaware County: 70 indexHarrison County: 87 indexJohnson County: 82 indexLee County: 69 indexLinn County: 97 indexMontgomery County: 84 indexMuscatine County: 80 indexPalo Alto County: 115 indexPolk County: 135 indexPottawattamie County: 74 indexScott County: 103 indexVan Buren County: 84 indexWarren County: 67 indexWoodbury County: 72 index
  • Under 71
  • 71 to 82
  • 82 to 85
  • 85 to 95
  • 95 and over
  • No data
Highest daily 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

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), 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: highest daily AQI, Highest daily 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/highest-daily-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: highest daily AQI. Highest daily 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/highest-daily-air-quality-index/delaware-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), Delaware County, 1987 to 2017 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/highest-daily-air-quality-index/delaware-county-iowa (Accessed: 12 October 2026).

BibTeX
@misc{environmental_highest_daily_air_quality_2017,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Highest daily 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/highest-daily-air-quality-index/delaware-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), 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/highest-daily-air-quality-index/delaware-county-iowa
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/highest-daily-air-quality-index/delaware-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 Delaware County?

Highest daily Air Quality Index (US EPA) in Delaware County was 70 in 2017, according to the U.S. Environmental Protection Agency. That is down 11 from 2016.

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 Delaware County?

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

Related statistics for Delaware County

All statistics for Delaware County | Delaware County in figures