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

Miami-Dade County had the highest highest daily Air Quality Index (US EPA) of 38 counties in 2021, at 135. Putnam County had the lowest, at 46. The median was 84. Source: the U.S. Environmental Protection Agency.

Highest135Miami-Dade County

Lowest46Putnam County

Median8438 counties

Map of counties, 2021

Under 74
74 to 79
79 to 84
84 to 88
88 to 95
95 and over
No data

index, 2021. 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, 2021

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

Full ranking

Rank	Counties	2021 index	Change on 2020
1	Miami-Dade County	135	+45
2	Hillsborough County	129	+17
3	Broward County	103	-39
4	Marion County	101	+1
5	Lee County	97	-3
5	Seminole County	97	+13
7	Pinellas County	95	-5
8	Duval County	94	-31
9	Highlands County	93	+19
9	Manatee County	93	-4
9	Osceola County	93	+3
12	Sarasota County	90	0
13	Martin County	88	-8
14	Baker County	87	-53
14	Lake County	87	0
14	Orange County	87	-6
14	Pasco County	87	+10
18	Alachua County	84	-21
18	Brevard County	84	-1
18	Polk County	84	-3
21	Citrus County	83	-42
21	Palm Beach County	83	-10
23	Collier County	81	-6
23	Wakulla County	81	-83
25	Leon County	80	-83
26	Santa Rosa County	79	-7
27	Bay County	78	-68
28	Columbia County	77	-83
28	Volusia County	77	0
30	Escambia County	75	-7
31	Holmes County	74	-64
31	Indian River County	74	-13
31	St. Lucie County	74	0
34	Hamilton County	69	-86
35	Flagler County	67	+3
36	Liberty County	61	+10
36	Okaloosa County	61	-13
38	Putnam County	46	-21

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. 4 counties with data in other periods have no value for 2021 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), 2021) [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), 2021. 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=2021. 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), 2021. 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=2021.

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), 2021 [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=2021 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_florida_by_2021,
  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), 2021}},
  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=2021. 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), 2021
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=2021
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/florida-counties?period=2021.
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)?

Miami-Dade County, with 135 in 2021, according to the U.S. Environmental Protection Agency.

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

Putnam County, with 46 in 2021.

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. 4 counties have no value for 2021 and are not ranked.