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

Counties in Louisiana by median Air Quality Index (US EPA), 2005

East Baton Rouge Parish had the highest median Air Quality Index (US EPA) of 28 counties in 2005, at 61. St. James Parish had the lowest, at 37. The median was 52. Source: the U.S. Environmental Protection Agency.

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Highest61East Baton Rouge Parish
Lowest37St. James Parish
Median5228 counties

Map of counties, 2005

Ascension Parish: 40 indexBeauregard Parish: 40 indexBossier Parish: 54 indexCaddo Parish: 46 indexCalcasieu Parish: 57 indexConcordia Parish: 55 indexEast Baton Rouge Parish: 61 indexGrant Parish: 41 indexIberville Parish: 50 indexJefferson Parish: 59 indexLafayette Parish: 47 indexLafourche Parish: 55 indexLivingston Parish: 55 indexOrleans Parish: 56 indexOuachita Parish: 46 indexPlaquemines Parish: 52 indexPointe Coupee Parish: 41 indexRapides Parish: 53 indexSt. Bernard Parish: 48 indexSt. Charles Parish: 38 indexSt. James Parish: 37 indexSt. John the Baptist Parish: 39 indexSt. Mary Parish: 39 indexSt. Tammany Parish: 59 indexTangipahoa Parish: 57 indexTerrebonne Parish: 52 indexWest Baton Rouge Parish: 59 indexWinn Parish: 52 index
  • Under 40
  • 40 to 48
  • 48 to 53
  • 53 to 57
  • 57 and over
  • No data
index, 2005. 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, 2005

East Baton Rouge Parish: 61 indexEast Baton Rouge Parish61Jefferson Parish: 59 indexJefferson Parish59St. Tammany Parish: 59 indexSt. Tammany Parish59West Baton Rouge Parish: 59 indexWest Baton Rouge Parish59Calcasieu Parish: 57 indexCalcasieu Parish57Tangipahoa Parish: 57 indexTangipahoa Parish57Orleans Parish: 56 indexOrleans Parish56Concordia Parish: 55 indexConcordia Parish55Lafourche Parish: 55 indexLafourche Parish55Livingston Parish: 55 indexLivingston Parish55Bossier Parish: 54 indexBossier Parish54Rapides Parish: 53 indexRapides Parish53Plaquemines Parish: 52 indexPlaquemines Parish52Terrebonne Parish: 52 indexTerrebonne Parish52Winn Parish: 52 indexWinn Parish52Iberville Parish: 50 indexIberville Parish50St. Bernard Parish: 48 indexSt. Bernard Parish48Lafayette Parish: 47 indexLafayette Parish47Caddo Parish: 46 indexCaddo Parish46Ouachita Parish: 46 indexOuachita Parish46Grant Parish: 41 indexGrant Parish41Pointe Coupee Parish: 41 indexPointe Coupee Parish41Ascension Parish: 40 indexAscension Parish40Beauregard Parish: 40 indexBeauregard Parish40St. John the Baptist Parish: 39 indexSt. John the Baptist Parish39St. Mary Parish: 39 indexSt. Mary Parish39St. Charles Parish: 38 indexSt. Charles Parish38St. James Parish: 37 indexSt. James Parish37East Baton Rouge Parish: 61 indexEast Baton Rouge Parish61Jefferson Parish: 59 indexJefferson Parish59St. Tammany Parish: 59 indexSt. Tammany Parish59West Baton Rouge Parish: 59 indexWest Baton Rouge Parish59Calcasieu Parish: 57 indexCalcasieu Parish57Tangipahoa Parish: 57 indexTangipahoa Parish57Orleans Parish: 56 indexOrleans Parish56Concordia Parish: 55 indexConcordia Parish55Lafourche Parish: 55 indexLafourche Parish55Livingston Parish: 55 indexLivingston Parish55Bossier Parish: 54 indexBossier Parish54Rapides Parish: 53 indexRapides Parish53Plaquemines Parish: 52 indexPlaquemines Parish52Terrebonne Parish: 52 indexTerrebonne Parish52Winn Parish: 52 indexWinn Parish52Iberville Parish: 50 indexIberville Parish50St. Bernard Parish: 48 indexSt. Bernard Parish48Lafayette Parish: 47 indexLafayette Parish47Caddo Parish: 46 indexCaddo Parish46Ouachita Parish: 46 indexOuachita Parish46Grant Parish: 41 indexGrant Parish41Pointe Coupee Parish: 41 indexPointe Coupee Parish41Ascension Parish: 40 indexAscension Parish40Beauregard Parish: 40 indexBeauregard Parish40St. John the Baptist Parish: 39 indexSt. John the Baptist Parish39St. Mary Parish: 39 indexSt. Mary Parish39St. Charles Parish: 38 indexSt. Charles Parish38St. James Parish: 37 indexSt. James Parish37
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2005
index		Change on 2004
1East Baton Rouge Parish61+5
2Jefferson Parish59+5
2St. Tammany Parish59n/a
2West Baton Rouge Parish59+3
5Calcasieu Parish57+5
5Tangipahoa Parish57+6
7Orleans Parish56+2
8Concordia Parish55+5
8Lafourche Parish55+3
8Livingston Parish55+6
11Bossier Parish54+3
12Rapides Parish53+5
13Plaquemines Parish52+10
13Terrebonne Parish52+8
13Winn Parish52+9
16Iberville Parish50+6
17St. Bernard Parish48+10
18Lafayette Parish47+5
19Caddo Parish46+3
19Ouachita Parish46+6
21Grant Parish41+4
21Pointe Coupee Parish41+8
23Ascension Parish40+6
23Beauregard Parish40+5
25St. John the Baptist Parish39+7
25St. Mary Parish39+5
27St. Charles Parish38+7
28St. James Parish37+6

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. 2 counties with data in other periods have no value for 2005 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), 2005) [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), 2005. 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. 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), 2005. 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.

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), 2005 [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 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_louisiana_by_2005,
  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), 2005}},
  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. 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), 2005
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
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/louisiana-counties.
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 61 in 2005, according to the U.S. Environmental Protection Agency.

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

St. James Parish, with 37 in 2005.

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. 2 counties have no value for 2005 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Louisiana: more rankings