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 2003, at 59. St. James Parish had the lowest, at 32. The median was 45. Source: the U.S. Environmental Protection Agency.

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Highest59East Baton Rouge Parish
Lowest32St. James Parish
Median4527 counties

Map of counties, 2003

Ascension Parish: 32 indexBeauregard Parish: 33 indexBossier Parish: 55 indexCaddo Parish: 44 indexCalcasieu Parish: 56 indexConcordia Parish: 54 indexEast Baton Rouge Parish: 59 indexGrant Parish: 36 indexIberville Parish: 45 indexJefferson Parish: 54 indexLafayette Parish: 43 indexLafourche Parish: 52 indexLivingston Parish: 53 indexOrleans Parish: 55 indexOuachita Parish: 44 indexPlaquemines Parish: 43 indexPointe Coupee Parish: 36 indexRapides Parish: 52 indexSt. Bernard Parish: 41 indexSt. Charles Parish: 32 indexSt. James Parish: 32 indexSt. John the Baptist Parish: 33 indexSt. Mary Parish: 33 indexTangipahoa Parish: 53 indexTerrebonne Parish: 52 indexWest Baton Rouge Parish: 56 indexWinn Parish: 50 index
  • Under 34
  • 34 to 43
  • 43 to 52
  • 52 to 54
  • 54 and over
  • No data
index, 2003. 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, 2003

East Baton Rouge Parish: 59 indexEast Baton Rouge Parish59Calcasieu Parish: 56 indexCalcasieu Parish56West Baton Rouge Parish: 56 indexWest Baton Rouge Parish56Bossier Parish: 55 indexBossier Parish55Orleans Parish: 55 indexOrleans Parish55Concordia Parish: 54 indexConcordia Parish54Jefferson Parish: 54 indexJefferson Parish54Livingston Parish: 53 indexLivingston Parish53Tangipahoa Parish: 53 indexTangipahoa Parish53Lafourche Parish: 52 indexLafourche Parish52Rapides Parish: 52 indexRapides Parish52Terrebonne Parish: 52 indexTerrebonne Parish52Winn Parish: 50 indexWinn Parish50Iberville Parish: 45 indexIberville Parish45Caddo Parish: 44 indexCaddo Parish44Ouachita Parish: 44 indexOuachita Parish44Lafayette Parish: 43 indexLafayette Parish43Plaquemines Parish: 43 indexPlaquemines Parish43St. Bernard Parish: 41 indexSt. Bernard Parish41Grant Parish: 36 indexGrant Parish36Pointe Coupee Parish: 36 indexPointe Coupee Parish36Beauregard Parish: 33 indexBeauregard Parish33St. John the Baptist Parish: 33 indexSt. John the Baptist Parish33St. Mary Parish: 33 indexSt. Mary Parish33Ascension Parish: 32 indexAscension Parish32St. Charles Parish: 32 indexSt. Charles Parish32St. James Parish: 32 indexSt. James Parish32East Baton Rouge Parish: 59 indexEast Baton Rouge Parish59Calcasieu Parish: 56 indexCalcasieu Parish56West Baton Rouge Parish: 56 indexWest Baton Rouge Parish56Bossier Parish: 55 indexBossier Parish55Orleans Parish: 55 indexOrleans Parish55Concordia Parish: 54 indexConcordia Parish54Jefferson Parish: 54 indexJefferson Parish54Livingston Parish: 53 indexLivingston Parish53Tangipahoa Parish: 53 indexTangipahoa Parish53Lafourche Parish: 52 indexLafourche Parish52Rapides Parish: 52 indexRapides Parish52Terrebonne Parish: 52 indexTerrebonne Parish52Winn Parish: 50 indexWinn Parish50Iberville Parish: 45 indexIberville Parish45Caddo Parish: 44 indexCaddo Parish44Ouachita Parish: 44 indexOuachita Parish44Lafayette Parish: 43 indexLafayette Parish43Plaquemines Parish: 43 indexPlaquemines Parish43St. Bernard Parish: 41 indexSt. Bernard Parish41Grant Parish: 36 indexGrant Parish36Pointe Coupee Parish: 36 indexPointe Coupee Parish36Beauregard Parish: 33 indexBeauregard Parish33St. John the Baptist Parish: 33 indexSt. John the Baptist Parish33St. Mary Parish: 33 indexSt. Mary Parish33Ascension Parish: 32 indexAscension Parish32St. Charles Parish: 32 indexSt. Charles Parish32St. James Parish: 32 indexSt. James Parish32
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2003
index		Change on 2002
1East Baton Rouge Parish59+2
2Calcasieu Parish56+8
2West Baton Rouge Parish56+2
4Bossier Parish55+7
4Orleans Parish55+2
6Concordia Parish54+2
6Jefferson Parish54+2
8Livingston Parish53+7
8Tangipahoa Parish53+1
10Lafourche Parish52+8
10Rapides Parish520
10Terrebonne Parish52+2
13Winn Parish50+6
14Iberville Parish45+3
15Caddo Parish440
15Ouachita Parish44+5
17Lafayette Parish43+3
17Plaquemines Parish43+9
19St. Bernard Parish41+1
20Grant Parish36+1
20Pointe Coupee Parish36+2
22Beauregard Parish33-1
22St. John the Baptist Parish330
22St. Mary Parish33+2
25Ascension Parish320
25St. Charles Parish320
25St. James Parish32+1

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 2003 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), 2003) [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), 2003. 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=2003. 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), 2003. 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=2003.

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), 2003 [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=2003 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_louisiana_by_2003,
  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), 2003}},
  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=2003. 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), 2003
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=2003
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/louisiana-counties?period=2003.
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 59 in 2003, according to the U.S. Environmental Protection Agency.

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

St. James Parish, with 32 in 2003.

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 2003 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Louisiana: more rankings