Median AQI
33
Good
Louisiana · County air quality · 2025
Ascension County, Louisiana
Median AQI 33 (Good). 94.1% of monitored days rated Good, direct from EPA Air Quality System stations.
- 33
- Median AQI
- 94.1%
- Good-air days
- 0
- Unhealthy days
- 86%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Ascension County's air is good on balance, cleaner than most US counties, a median AQI of 33 with 94.1% of 272 monitored days in the Good band, driven mainly by Ozone.
- 33
- median AQI · Good
- 94.1%
- days rated Good
- Ozone
- main pollutant
- 86%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 108.
Data updated July 2026
- Good · 256 d · 94.1%
- Moderate · 15 d · 5.5%
- USG · 1 d · 0.4%
How did Ascension County's air break down in 2025?
Across 272 monitored days, 256 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 108 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 272 days monitored. Median AQI: 33 (Good).
Insights: Ascension County, Louisiana. EPA monitors recorded a median Air Quality Index of 33 across 272 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 256 (94%) fell in the Good band (AQI 0–50), 15 (6%) registered Moderate readings, and 1 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 48, while the worst single-day peak hit 108 (USG). Residents averaged about 28.2 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (267 days), NO2 (5 days). Across the 2020–2025 trend window, good days shifted by -94 and the median AQI moved +2 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 108, usg but never Unhealthy. Nearby counties show comparable readings: 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); Jefferson (58.6% good, AQI 48).
Air Quality Summary
Good Days
94.1%
256 of 272 monitored days
19.1pp vs 75% target
Max AQI Recorded
108
USG
Health Grade
Excellent
90th-pct AQI 48
Ascension County, Good days share 94.1%
National avg
Share of monitored days at AQI 0-50 (Good band).
Ascension 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 272 monitored days across EPA AQI categories.
Good
256
94%
Moderate
15
6%
USG
1
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 Ascension County.
- Ozone · 267 days · 98.2%
- NO₂ · 5 days · 1.8%
Health Impact Assessment
Excellent
Ascension County's air quality is rated Excellent based on 94.1% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 94.1% of monitored days in 2025, with a median AQI of 33. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 267 of 272 monitored days.
5-Year Air Quality Trend
Air quality is stable in Ascension County. Best year: 2020 (350 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 350 | 14 | 0 | 0 | 31 | 100 |
| 2021 | 338 | 16 | 1 | 1 | 31 | 159 |
| 2022 | 336 | 28 | 0 | 0 | 32 | 90 |
| 2023 | 310 | 49 | 2 | 1 | 34 | 154 |
| 2024 | 331 | 26 | 2 | 1 | 33 | 151 |
| 2025 | 256 | 15 | 1 | 0 | 33 | 108 |
How does Ascension County compare?
How Ascension County compares
Good-day share better than US avg
Ascension County 94.1%
Bossier County, Louisiana 86.5%
US average 76.5%
Median AQI better than US avg
Ascension County 33
Bossier County, Louisiana 40
US average 38
Unhealthy days / yr about average
Ascension County 0
Bossier 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 Ascension County.
Athens County, Ohio
AQI 33 · 80.3% good
Brazoria County, Texas
AQI 33 · 84.8% good
Bristol City County, Virginia
AQI 33 · 78.3% good
Carter County, Oklahoma
AQI 33 · 80.9% good
Codington County, South Dakota
AQI 33 · 82.1% good
Del Norte County, California
AQI 33 · 81.0% good
What Ascension 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 33 means for exposure. Health guidance
- See how Ascension County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Ascension County with its Louisiana neighbours before drawing a conclusion about the region. All of Louisiana
Based on 272 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 Ascension County, Louisiana? ▼
Ascension County has a median Air Quality Index (AQI) of 33, rated "Good." 94.1% of monitored days (256 out of 272) had good air quality in 2025.
What is the main pollutant in Ascension County? ▼
The primary pollutant in Ascension County is Ozone (O3), which was the main AQI driver on 267 days (98% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Ascension County have? ▼
In 2025, Ascension County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 108.
Is the air quality in Ascension County getting better or worse? ▼
Air quality in Ascension County is stable based on 5-year trends (2020-2025). Best year: 2020 with 350 good days. Worst year: 2025 with 256 good days.
What does AQI 33 mean for health? ▼
Ascension County's median AQI of 33 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 Ascension County compare to other counties in Louisiana? ▼
Ascension County has 94.1% good air days. Nearby counties in Louisiana: Bossier (86.5% good), Caddo (84.3% good), Calcasieu (61.5% good), East Baton Rouge (49.3% good), Iberville (78.4% good), Jefferson (58.6% good).
What is the 90th percentile AQI in Ascension County? ▼
The 90th percentile AQI for Ascension County is 48, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 108 (USG).
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.