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

Monroe County had the highest highest daily Air Quality Index (US EPA) of 35 counties in 2009, at 165. St. Lawrence County had the lowest, at 85. The median was 115. Source: the U.S. Environmental Protection Agency.

Highest165Monroe County

Lowest85St. Lawrence County

Median11535 counties

Map of counties, 2009

Under 99
99 to 110
110 to 120
120 to 140
140 and over
No data

index, 2009. 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, 2009

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

Full ranking

Rank	Counties	2009 index	Change on 2008
1	Monroe County	165	+18
2	Jefferson County	154	+14
3	Suffolk County	151	-39
4	Richmond County	150	+35
5	Bronx County	147	-4
5	Franklin County	147	+21
7	Essex County	136	-23
8	Chautauqua County	133	-23
9	Niagara County	129	0
9	Putnam County	129	-37
11	Erie County	126	-3
11	New York County	126	-35
13	Dutchess County	122	-34
13	Rensselaer County	122	-25
13	Saratoga County	122	-34
16	Onondaga County	119	-31
16	Westchester County	119	-71
18	Albany County	115	-41
19	Queens County	112	-44
19	Schenectady County	112	-39
21	Nassau County	108	0
21	Orange County	108	-93
21	Oswego County	108	-35
21	Ulster County	108	-39
25	Hamilton County	105	-17
25	Herkimer County	105	-35
25	Kings County	105	-4
28	Steuben County	101	-42
29	Rockland County	100	n/a
30	Chemung County	97	-50
30	Madison County	97	-64
30	Wayne County	97	-53
33	Tompkins County	93	-57
34	Oneida County	88	-45
35	St. Lawrence County	85	+19

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 2009 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 New York by highest daily Air Quality Index (US EPA), 2009) [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 New York by highest daily Air Quality Index (US EPA), 2009. 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/new-york-counties?period=2009. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Counties in New York by highest daily Air Quality Index (US EPA), 2009. 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/new-york-counties?period=2009.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Counties in New York by highest daily Air Quality Index (US EPA), 2009 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/highest-daily-air-quality-index/new-york-counties?period=2009 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_new_york_2009,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Counties in New York by highest daily Air Quality Index (US EPA), 2009}},
  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/new-york-counties?period=2009. 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 New York by highest daily Air Quality Index (US EPA), 2009
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/new-york-counties?period=2009
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/new-york-counties?period=2009.
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

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

Monroe County, with 165 in 2009, according to the U.S. Environmental Protection Agency.

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

St. Lawrence County, with 85 in 2009.

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 2009 and are not ranked.