Data / Highest daily Air Quality Index (US EPA) / St. Johns County

Highest daily Air Quality Index (US EPA) in St. Johns County

Highest daily Air Quality Index (US EPA) in St. Johns County was 39 in 1998, according to the U.S. Environmental Protection Agency. That is down 104 from 1997.

1998, index39
Change on 1997-104
Series high1821994
Series low241983

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 St. Johns County, 1983 to 1998

05010015020019831993199519981983: 24 index1992: 90 index1993: 147 index1994: 182 index1995: 161 index1996: 154 index1997: 143 index1998: 39 index0501001502001983199419981983: 24 index1992: 90 index1993: 147 index1994: 182 index1995: 161 index1996: 154 index1997: 143 index1998: 39 index
index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 8 values
Periodindex
199839
1997143
1996154
1995161
1994182
1993147
199290
198324

St. Johns County compared with nearby places

Alachua County: 192 indexBaker County: 147 indexBay County: 60 indexBrevard County: 210 indexBroward County: 195 indexCitrus County: 91 indexCollier County: 57 indexDuval County: 214 indexEscambia County: 212 indexGulf County: 59 indexHamilton County: 184 indexHillsborough County: 218 indexHolmes County: 166 indexLake County: 57 indexLee County: 174 indexLeon County: 143 indexLiberty County: 161 indexManatee County: 209 indexMarion County: 166 indexMartin County: 23 indexMiami-Dade County: 185 indexMonroe County: 65 indexNassau County: 73 indexOrange County: 203 indexOsceola County: 182 indexPalm Beach County: 161 indexPasco County: 185 indexPinellas County: 207 indexPolk County: 200 indexPutnam County: 91 indexSt. Johns County: 39 indexSt. Lucie County: 156 indexSarasota County: 203 indexSeminole County: 174 indexVolusia County: 205 index
  • Under 63
  • 63 to 150
  • 150 to 170
  • 170 to 190
  • 190 to 210
  • 210 and over
  • No data
Highest daily Air Quality Index (US EPA), 1998, index. St. Johns 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), St. Johns County, 1983 to 1998) [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), St. Johns County, 1983 to 1998. 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/st-johns-county-florida. 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), St. Johns County, 1983 to 1998. 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/st-johns-county-florida.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Highest daily Air Quality Index (US EPA), St. Johns County, 1983 to 1998 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/highest-daily-air-quality-index/st-johns-county-florida (Accessed: 12 October 2026).

BibTeX
@misc{environmental_highest_daily_air_quality_1998,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Highest daily Air Quality Index (US EPA), St. Johns County, 1983 to 1998}},
  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/st-johns-county-florida. 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), St. Johns County, 1983 to 1998
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/st-johns-county-florida
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/highest-daily-air-quality-index/st-johns-county-florida.
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 St. Johns County?

Highest daily Air Quality Index (US EPA) in St. Johns County was 39 in 1998, according to the U.S. Environmental Protection Agency. That is down 104 from 1997.

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 St. Johns County?

182 in 1994, the highest value since 1983 in this series.

Related statistics for St. Johns County

All statistics for St. Johns County | St. Johns County in figures