Data / Rankings / Median Air Quality Index (US EPA) / Counties in Louisiana

Counties in Louisiana by median Air Quality Index (US EPA)

East Baton Rouge Parish had the highest median Air Quality Index (US EPA) of 27 counties in 2002, at 57. St. Mary Parish had the lowest, at 31. The median was 44. Source: the U.S. Environmental Protection Agency.

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Highest57East Baton Rouge Parish
Lowest31St. Mary Parish
Median4427 counties

Map of counties, 2002

Ascension Parish: 32 indexBeauregard Parish: 34 indexBossier Parish: 48 indexCaddo Parish: 44 indexCalcasieu Parish: 48 indexConcordia Parish: 52 indexEast Baton Rouge Parish: 57 indexGrant Parish: 35 indexIberville Parish: 42 indexJefferson Parish: 52 indexLafayette Parish: 40 indexLafourche Parish: 44 indexLivingston Parish: 46 indexOrleans Parish: 53 indexOuachita Parish: 39 indexPlaquemines Parish: 34 indexPointe Coupee Parish: 34 indexRapides Parish: 52 indexSt. Bernard Parish: 40 indexSt. Charles Parish: 32 indexSt. James Parish: 31 indexSt. John the Baptist Parish: 33 indexSt. Mary Parish: 31 indexTangipahoa Parish: 52 indexTerrebonne Parish: 50 indexWest Baton Rouge Parish: 54 indexWinn Parish: 44 index
  • Under 34
  • 34 to 40
  • 40 to 45
  • 45 to 52
  • 52 and over
  • No data
index, 2002. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2002

East Baton Rouge Parish: 57 indexEast Baton Rouge Parish57West Baton Rouge Parish: 54 indexWest Baton Rouge Parish54Orleans Parish: 53 indexOrleans Parish53Concordia Parish: 52 indexConcordia Parish52Jefferson Parish: 52 indexJefferson Parish52Rapides Parish: 52 indexRapides Parish52Tangipahoa Parish: 52 indexTangipahoa Parish52Terrebonne Parish: 50 indexTerrebonne Parish50Bossier Parish: 48 indexBossier Parish48Calcasieu Parish: 48 indexCalcasieu Parish48Livingston Parish: 46 indexLivingston Parish46Caddo Parish: 44 indexCaddo Parish44Lafourche Parish: 44 indexLafourche Parish44Winn Parish: 44 indexWinn Parish44Iberville Parish: 42 indexIberville Parish42Lafayette Parish: 40 indexLafayette Parish40St. Bernard Parish: 40 indexSt. Bernard Parish40Ouachita Parish: 39 indexOuachita Parish39Grant Parish: 35 indexGrant Parish35Beauregard Parish: 34 indexBeauregard Parish34Plaquemines Parish: 34 indexPlaquemines Parish34Pointe Coupee Parish: 34 indexPointe Coupee Parish34St. John the Baptist Parish: 33 indexSt. John the Baptist Parish33Ascension Parish: 32 indexAscension Parish32St. Charles Parish: 32 indexSt. Charles Parish32St. James Parish: 31 indexSt. James Parish31St. Mary Parish: 31 indexSt. Mary Parish31East Baton Rouge Parish: 57 indexEast Baton Rouge Parish57West Baton Rouge Parish: 54 indexWest Baton Rouge Parish54Orleans Parish: 53 indexOrleans Parish53Concordia Parish: 52 indexConcordia Parish52Jefferson Parish: 52 indexJefferson Parish52Rapides Parish: 52 indexRapides Parish52Tangipahoa Parish: 52 indexTangipahoa Parish52Terrebonne Parish: 50 indexTerrebonne Parish50Bossier Parish: 48 indexBossier Parish48Calcasieu Parish: 48 indexCalcasieu Parish48Livingston Parish: 46 indexLivingston Parish46Caddo Parish: 44 indexCaddo Parish44Lafourche Parish: 44 indexLafourche Parish44Winn Parish: 44 indexWinn Parish44Iberville Parish: 42 indexIberville Parish42Lafayette Parish: 40 indexLafayette Parish40St. Bernard Parish: 40 indexSt. Bernard Parish40Ouachita Parish: 39 indexOuachita Parish39Grant Parish: 35 indexGrant Parish35Beauregard Parish: 34 indexBeauregard Parish34Plaquemines Parish: 34 indexPlaquemines Parish34Pointe Coupee Parish: 34 indexPointe Coupee Parish34St. John the Baptist Parish: 33 indexSt. John the Baptist Parish33Ascension Parish: 32 indexAscension Parish32St. Charles Parish: 32 indexSt. Charles Parish32St. James Parish: 31 indexSt. James Parish31St. Mary Parish: 31 indexSt. Mary Parish31
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2002
index		Change on 2001
1East Baton Rouge Parish57-2
2West Baton Rouge Parish54-2
3Orleans Parish53-2
4Concordia Parish52-3
4Jefferson Parish52-2
4Rapides Parish52-3
4Tangipahoa Parish52-2
8Terrebonne Parish50-2
9Bossier Parish48-4
9Calcasieu Parish48-5
11Livingston Parish46-6
12Caddo Parish44-1
12Lafourche Parish44-5
12Winn Parish44-9
15Iberville Parish42-2
16Lafayette Parish40-1
16St. Bernard Parish40-4
18Ouachita Parish39-3
19Grant Parish35-4
20Beauregard Parish34-2
20Plaquemines Parish34-9
20Pointe Coupee Parish34+3
23St. John the Baptist Parish33-3
24Ascension Parish32-4
24St. Charles Parish32-1
26St. James Parish310
26St. Mary Parish31-3

Other periods

About this ranking

Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries.

More on how it is measured
  • The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide).
  • Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.

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 2002 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: median 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: median daily AQI (Counties in Louisiana by median Air Quality Index (US EPA), 2002) [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: median daily AQI, Counties in Louisiana by median Air Quality Index (US EPA), 2002. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/median-air-quality-index/louisiana-counties?period=2002. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Louisiana by median Air Quality Index (US EPA), 2002. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/median-air-quality-index/louisiana-counties?period=2002.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Louisiana by median Air Quality Index (US EPA), 2002 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/louisiana-counties?period=2002 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_louisiana_by_2002,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Louisiana by median Air Quality Index (US EPA), 2002}},
  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/median-air-quality-index/louisiana-counties?period=2002. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median 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: median daily AQI: Counties in Louisiana by median Air Quality Index (US EPA), 2002
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/median-air-quality-index/louisiana-counties?period=2002
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/louisiana-counties?period=2002.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Rank Counties in Louisiana by median Air Quality Index (US EPA) using official data, and cite the source.
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Questions

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

East Baton Rouge Parish, with 57 in 2002, according to the U.S. Environmental Protection Agency.

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

St. Mary Parish, with 31 in 2002.

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: median daily AQI. Retrieved 2026-10-12. 3 counties have no value for 2002 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Louisiana: more rankings