EnviroNearby

St. Mary Parish, Louisiana air quality history

Daily Air Quality Index summaries from EPA monitors in St. Mary, Louisiana, 1983–2005.

75%
Good days in 2005
39
Median daily AQI, 2005
18
Days above 100 in 2005
358
Days with an AQI in 2005 (of 365)

In 2005, EPA reported a daily Air Quality Index (AQI) for St. Mary, Louisiana on 358 days. 270 of those days (75%) were in the Good range, and the median daily AQI was 39. That median is lower than the typical monitored county in Louisiana (median 48 across 23 counties), and lower than the typical monitored U.S. county (44). The main pollutant was ozone on 358 days. Across the years with fuller monitoring, the share of Good days fell: an average of 82% in 1983–1990 versus 80% in 2003–2005.

The most recent year with data for this county is 2005; EPA's files for 2006–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1984, 1988) are shown in the table but left out of comparisons and trend statements.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Share of monitored days in each AQI category, by year0%25%50%75%100%1983: Good 100 of 129 days1983: Moderate 19 of 129 days1983: Unhealthy for Sensitive Groups 10 of 129 days19831984: Good 94 of 101 days1984: Moderate 5 of 101 days1984: Unhealthy for Sensitive Groups 2 of 101 days1988: Good 89 of 92 days1988: Moderate 3 of 92 days19881989: Good 290 of 344 days1989: Moderate 45 of 344 days1989: Unhealthy for Sensitive Groups 8 of 344 days1989: Unhealthy 1 of 344 days1990: Good 304 of 356 days1990: Moderate 41 of 356 days1990: Unhealthy for Sensitive Groups 10 of 356 days1990: Unhealthy 1 of 356 days19901991: Good 343 of 358 days1991: Moderate 14 of 358 days1991: Unhealthy for Sensitive Groups 1 of 358 days1992: Good 340 of 363 days1992: Moderate 23 of 363 days19921993: Good 323 of 365 days1993: Moderate 37 of 365 days1993: Unhealthy for Sensitive Groups 4 of 365 days1993: Unhealthy 1 of 365 days1994: Good 332 of 364 days1994: Moderate 29 of 364 days1994: Unhealthy for Sensitive Groups 3 of 364 days19941995: Good 207 of 267 days1995: Moderate 27 of 267 days1995: Unhealthy for Sensitive Groups 26 of 267 days1995: Unhealthy 7 of 267 days1996: Good 302 of 357 days1996: Moderate 49 of 357 days1996: Unhealthy for Sensitive Groups 6 of 357 days19961997: Good 271 of 363 days1997: Moderate 61 of 363 days1997: Unhealthy for Sensitive Groups 30 of 363 days1997: Unhealthy 1 of 363 days1998: Good 286 of 353 days1998: Moderate 40 of 353 days1998: Unhealthy for Sensitive Groups 21 of 353 days1998: Unhealthy 5 of 353 days1998: Very Unhealthy 1 of 353 days19981999: Good 267 of 352 days1999: Moderate 60 of 352 days1999: Unhealthy for Sensitive Groups 20 of 352 days1999: Unhealthy 5 of 352 days2000: Good 282 of 358 days2000: Moderate 48 of 358 days2000: Unhealthy for Sensitive Groups 23 of 358 days2000: Unhealthy 5 of 358 days20002001: Good 297 of 362 days2001: Moderate 47 of 362 days2001: Unhealthy for Sensitive Groups 18 of 362 days2002: Good 314 of 353 days2002: Moderate 36 of 353 days2002: Unhealthy for Sensitive Groups 3 of 353 days20022003: Good 288 of 342 days2003: Moderate 41 of 342 days2003: Unhealthy for Sensitive Groups 13 of 342 days2004: Good 277 of 349 days2004: Moderate 62 of 349 days2004: Unhealthy for Sensitive Groups 9 of 349 days2004: Unhealthy 1 of 349 days20042005: Good 270 of 358 days2005: Moderate 70 of 358 days2005: Unhealthy for Sensitive Groups 18 of 358 days2005
  • Good
  • Moderate
  • Unhealthy for Sensitive Groups
  • Unhealthy
  • Very Unhealthy
  • Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median and 90th-percentile daily AQI, by year0501001501983: 90th percentile AQI 931984: 90th percentile AQI 441988: 90th percentile AQI 441989: 90th percentile AQI 581990: 90th percentile AQI 641991: 90th percentile AQI 451992: 90th percentile AQI 461993: 90th percentile AQI 531994: 90th percentile AQI 501995: 90th percentile AQI 1051996: 90th percentile AQI 671997: 90th percentile AQI 931998: 90th percentile AQI 841999: 90th percentile AQI 872000: 90th percentile AQI 842001: 90th percentile AQI 772002: 90th percentile AQI 512003: 90th percentile AQI 672004: 90th percentile AQI 772005: 90th percentile AQI 871983: Median AQI 281984: Median AQI 221988: Median AQI 291989: Median AQI 291990: Median AQI 311991: Median AQI 251992: Median AQI 281993: Median AQI 331994: Median AQI 301995: Median AQI 341996: Median AQI 351997: Median AQI 361998: Median AQI 351999: Median AQI 362000: Median AQI 352001: Median AQI 342002: Median AQI 312003: Median AQI 332004: Median AQI 342005: Median AQI 3919831988199019921994199619982000200220042005
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2005

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

PollutantDays as main pollutantShare of monitored days
Ozone358100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
200535827070180003987136Ozone
20043492776291003477154Ozone
200334228841130003367133Ozone
20023533143630003151105Ozone
200136229747180003477126Ozone
200035828248235003584190Ozone
199935226760205003687159Ozone
199835328640215103584210Ozone
199736327161301003693182Ozone
19963573024960003567140Ozone
1995267207272670034105177Ozone
19943643322930003050112Ozone
19933653233741003353156Ozone
1992363340230000284693Ozone
19913583431410002545129Ozone
199035630441101003164151Ozone
19893442904581002958151Ozone
1988928930000294458Ozone
198410194520002244143Ozone
198312910019100002893143Ozone

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

Counties in Louisiana with a similar median AQI in 2005

All monitored counties in Louisiana

Source: U.S. EPA AirData, “Annual AQI by County” files for 1983–2005 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem