Counties in Florida by highest daily Air Quality Index (US EPA)

Duval County had the highest highest daily Air Quality Index (US EPA) of 39 counties in 2018, at 156. Putnam County had the lowest, at 51. The median was 100. Source: the U.S. Environmental Protection Agency.

Highest156Duval County

Lowest51Putnam County

Median10039 counties

Map of counties, 2018

Under 80
80 to 90
90 to 100
100 to 110
110 to 130
130 and over
No data

index, 2018. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2018

index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2018 index	Change on 2017
1	Duval County	156	+55
2	Orange County	151	+4
3	Seminole County	150	+17
4	Brevard County	129	+32
4	Pasco County	129	+17
6	Bay County	126	+29
6	Miami-Dade County	126	-10
6	Osceola County	126	-7
9	Hillsborough County	122	-28
10	Manatee County	119	-14
11	Martin County	112	-3
11	Polk County	112	-31
13	Columbia County	111	+11
14	Highlands County	108	+18
15	Lee County	106	+16
16	Indian River County	101	0
16	Lake County	101	-21
18	Broward County	100	-43
18	Pinellas County	100	-40
18	St. Lucie County	100	-12
21	Wakulla County	98	+5
22	Leon County	97	+8
22	Sarasota County	97	-18
24	Escambia County	93	-22
25	Palm Beach County	91	-21
26	Alachua County	90	-3
26	Marion County	90	-11
26	Santa Rosa County	90	-7
29	Baker County	87	-3
30	Nassau County	86	-7
31	Holmes County	81	-2
32	Collier County	80	-13
32	Okaloosa County	80	-7
32	Volusia County	80	-15
35	Flagler County	77	-16
36	Citrus County	73	-23
37	Liberty County	71	+10
38	Hamilton County	69	-15
39	Putnam County	51	-2

Other periods

About this ranking

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.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. 3 counties with data in other periods have no value for 2018 and are left out rather than filled from another source. Equal values share a rank.

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 (Counties in Florida by highest daily Air Quality Index (US EPA), 2018) [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, Counties in Florida by highest daily Air Quality Index (US EPA), 2018. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/florida-counties?period=2018. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Counties in Florida by highest daily Air Quality Index (US EPA), 2018. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/florida-counties?period=2018.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Counties in Florida by highest daily Air Quality Index (US EPA), 2018 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/highest-daily-air-quality-index/florida-counties?period=2018 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_florida_by_2018,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Counties in Florida by highest daily Air Quality Index (US EPA), 2018}},
  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/rankings/highest-daily-air-quality-index/florida-counties?period=2018. 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: Counties in Florida by highest daily Air Quality Index (US EPA), 2018
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/rankings/highest-daily-air-quality-index/florida-counties?period=2018
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/florida-counties?period=2018.
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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Rank Counties in Florida by highest daily Air Quality Index (US EPA) using official data, and cite the source.

rank_places {"indicator":"aqi_max","level":"province","within":"Florida","limit":10}
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Questions

Which county has the highest highest daily Air Quality Index (US EPA)?

Duval County, with 156 in 2018, according to the U.S. Environmental Protection Agency.

Which county has the lowest highest daily Air Quality Index (US EPA)?

Putnam County, with 51 in 2018.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12. 3 counties have no value for 2018 and are not ranked.