Median AQI
45
Good
Louisiana · County air quality · 2025
St. Bernard County, Louisiana
Median AQI 45 (Good). 69.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 45
- Median AQI
- 69.6%
- Good-air days
- 0
- Unhealthy days
- 31%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, St. Bernard County's air is good on balance, more polluted than the median US county, a median AQI of 45 with 69.6% of 273 monitored days in the Good band, driven mainly by Ozone.
- 45
- median AQI · Good
- 69.6%
- days rated Good
- Ozone
- main pollutant
- 31%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 93.
Data updated July 2026
- Good · 190 d · 69.6%
- Moderate · 83 d · 30.4%
How did St. Bernard County's air break down in 2025?
Across 273 monitored days, 190 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 93 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 273 days monitored. Median AQI: 45 (Good).
Insights: St. Bernard County, Louisiana. EPA monitors recorded a median Air Quality Index of 45 across 273 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 190 (70%) fell in the Good band (AQI 0–50), 83 (30%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 59, while the worst single-day peak hit 93 (Moderate). Residents averaged about 20.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (142 days), PM2.5 (131 days). Across the 2020–2025 trend window, good days shifted by -39 and the median AQI moved +1 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 93, moderate but never Unhealthy. Nearby counties show comparable readings: Ascension (94.1% good, AQI 33); Bossier (86.5% good, AQI 40); Caddo (84.3% good, AQI 38); Calcasieu (61.5% good, AQI 47); East Baton Rouge (49.3% good, AQI 51); Iberville (78.4% good, AQI 41).
Air Quality Summary
Good Days
69.6%
190 of 273 monitored days
-5.4pp vs 75% target
Max AQI Recorded
93
Moderate
Health Grade
Moderate
90th-pct AQI 59
St. Bernard County, Good days share 69.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
St. Bernard County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 273 monitored days across EPA AQI categories.
Good
190
70%
Moderate
83
30%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in St. Bernard County.
- Ozone · 142 days · 52.0%
- PM2.5 · 131 days · 48.0%
Health Impact Assessment
Moderate
St. Bernard County's air quality is rated Moderate based on 69.6% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 69.6% of monitored days in 2025, with a median AQI of 45. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 142 of 273 monitored days.
5-Year Air Quality Trend
Air quality is improving in St. Bernard County. Best year: 2024 (241 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 229 | 128 | 0 | 0 | 44 | 86 |
| 2021 | 206 | 153 | 0 | 0 | 47 | 80 |
| 2022 | 209 | 155 | 1 | 0 | 47 | 108 |
| 2023 | 156 | 207 | 2 | 0 | 52 | 119 |
| 2024 | 241 | 123 | 2 | 0 | 45 | 138 |
| 2025 | 190 | 83 | 0 | 0 | 45 | 93 |
How does St. Bernard County compare?
How St. Bernard County compares
Good-day share worse than US avg
St. Bernard County 69.6%
Ascension County, Louisiana 94.1%
US average 76.5%
Median AQI worse than US avg
St. Bernard County 45
Ascension County, Louisiana 33
US average 38
Unhealthy days / yr about average
St. Bernard County 0
Ascension County, Louisiana 0
US average 0
Other Counties in Louisiana
Air quality comparison for nearby counties in Louisiana.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to St. Bernard County.
Adair County, Oklahoma
AQI 45 · 59.2% good
Allen County, Indiana
AQI 45 · 58.2% good
Atascosa County, Texas
AQI 45 · 58.0% good
Baker County, Florida
AQI 45 · 69.1% good
Carson City County, Nevada
AQI 45 · 79.3% good
Clinton County, Iowa
AQI 45 · 59.9% good
What St. Bernard County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 45 means for exposure. Health guidance
- See how St. Bernard County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare St. Bernard County with its Louisiana neighbours before drawing a conclusion about the region. All of Louisiana
Based on 273 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in St. Bernard County, Louisiana? ▼
St. Bernard County has a median Air Quality Index (AQI) of 45, rated "Good." 69.6% of monitored days (190 out of 273) had good air quality in 2025.
What is the main pollutant in St. Bernard County? ▼
The primary pollutant in St. Bernard County is Ozone (O3), which was the main AQI driver on 142 days (52% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does St. Bernard County have? ▼
In 2025, St. Bernard County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 93.
Is the air quality in St. Bernard County getting better or worse? ▼
Air quality in St. Bernard County is improving based on 5-year trends (2020-2025). Best year: 2024 with 241 good days. Worst year: 2023 with 156 good days.
What does AQI 45 mean for health? ▼
St. Bernard County's median AQI of 45 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does St. Bernard County compare to other counties in Louisiana? ▼
St. Bernard County has 69.6% good air days. Nearby counties in Louisiana: Ascension (94.1% good), Bossier (86.5% good), Caddo (84.3% good), Calcasieu (61.5% good), East Baton Rouge (49.3% good), Iberville (78.4% good).
What is the 90th percentile AQI in St. Bernard County? ▼
The 90th percentile AQI for St. Bernard County is 59, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 93 (Moderate).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer.
Every figure on PlainAir is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.