Median AQI
41
Good
Delaware · County air quality · 2025
Kent County, Delaware
Median AQI 41 (Good). 75.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 41
- Median AQI
- 75.6%
- Good-air days
- 0
- Unhealthy days
- 45%
- Cleaner than US counties
Kent County's 2025 annual median AQI is 41 (Good), with 75.6% Good days
According to the U.S. EPA Air Quality System, Kent County, Delaware posted a 2025 median AQI of 41 (Good) across 365 monitored days, with 75.6% rated Good and 0 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Kent County's 75.6% Good-day share places it cleaner than 45% of US counties in 2025.
- Closest median-AQI peer
- Armstrong County (70.5% Good, median AQI 41) is the closest nationwide median-AQI peer to Kent County.
- 2020–2025 trend
- Kent County's floor-qualifying Good-day share is worsening from 2020 to 2025 (81.8% → 75.6%).
- Median AQI
- Median AQI: 41
The verdict
According to EPA Air Quality System monitoring data, Kent County's air is good on balance, more polluted than the median US county, a median AQI of 41 with 75.6% of 365 monitored days in the Good band, driven mainly by Ozone.
- 41
- median AQI · Good
- 75.6%
- days rated Good
- Ozone
- main pollutant
- 45%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 122.
Annual release change
What changed in the 2025 EPA annual release
- Kent County's peak single-day AQI rose from 100 to 122 between the 2024 and 2025 EPA annual releases, a change of +22 points.
- Kent County's Good-day share rose from 74.4% to 75.6% between the 2024 and 2025 EPA annual releases, a change of +1.2 percentage points.
Data updated August 2026
- Good · 276 d · 75.6%
- Moderate · 85 d · 23.3%
- USG · 4 d · 1.1%
How did Kent County's air break down in 2025?
Across 365 monitored days, 276 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 122 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 365 days monitored. Median AQI: 41 (Good).
Insights: Kent County, Delaware. EPA monitors recorded a median Air Quality Index of 41 across 365 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 276 (76%) fell in the Good band (AQI 0–50), 85 (23%) registered Moderate readings, and 4 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 62, while the worst single-day peak hit 122 (USG). Residents averaged about 22.7 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (229 days), PM2.5 (136 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -6.2 points and the median AQI moved +2 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 122, usg but never Unhealthy. Nearby counties show comparable readings: New Castle (64.4% good, AQI 44); Sussex (82.2% good, AQI 39).
Air Quality Summary
Good Days
75.6%
276 of 365 monitored days
0.6pp vs 75% target
Max AQI Recorded
122
USG
Health Grade
Good
90th-pct AQI 62
Kent County, Good days share 75.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
Kent 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 365 monitored days across EPA AQI categories.
Good
276
76%
Moderate
85
23%
USG
4
1%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Kent County.
- Ozone · 229 days · 62.7%
- PM2.5 · 136 days · 37.3%
Health Impact Assessment
Good
Kent County's air quality is rated Good based on 75.6% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 75.6% of monitored days in 2025, with a median AQI of 41. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 229 of 365 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Kent County. Highest Good-day share: 2020 (81.8%, 296 of 362 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 296 | 66 | 0 | 0 | 39 | 80 |
| 2021 | 260 | 98 | 2 | 0 | 42 | 108 |
| 2022 | 277 | 87 | 0 | 0 | 42 | 84 |
| 2023 | 216 | 124 | 5 | 2 | 46 | 207 |
| 2024 | 250 | 86 | 0 | 0 | 41 | 100 |
| 2025 | 276 | 85 | 4 | 0 | 41 | 122 |
How does Kent County compare?
How Kent County compares
Good-day share about average
Kent County 75.6%
Armstrong County, Pennsylvania 70.5%
US average 76.0%
Median AQI worse than US avg
Kent County 41
Armstrong County, Pennsylvania 41
US average 39
Unhealthy days / yr better than US avg
Kent County 0
Armstrong County, Pennsylvania 0
US average 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Kent County (41), not geographic neighbors.
Armstrong County, Pennsylvania
Median AQI 41 · 70.5% Good-day share
Benewah County, Idaho
Median AQI 41 · 63.4% Good-day share
Berrien County, Michigan
Median AQI 41 · 80.9% Good-day share
Callaway County, Missouri
Median AQI 41 · 89.6% Good-day share
Cambria County, Pennsylvania
Median AQI 41 · 74.5% Good-day share
Cass County, Missouri
Median AQI 41 · 77.6% Good-day share
Same primary pollutant: Ozone
Ozone led the AQI on the most monitored days here. These peers share that driver and the closest Good-day share (a second relationship type beyond median-AQI neighbors).
Shasta County, California
75.6% Good-day share · median AQI 44
Trego County, Kansas
75.5% Good-day share · median AQI 41
Harford County, Maryland
75.5% Good-day share · median AQI 42
Collin County, Texas
75.8% Good-day share · median AQI 40
Henrico County, Virginia
75.8% Good-day share · median AQI 40
Gilpin County, Colorado
75.8% Good-day share · median AQI 46
Delaware counties on the map
Geographic containment only, other monitored counties in Delaware, independent of AQI or pollutant match.
What Kent 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 41 means for exposure. Health guidance
- See how Kent County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Kent County with its Delaware neighbours before drawing a conclusion about the region. All of Delaware
Based on 365 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Kent County, Delaware? ▼
Kent County has a median Air Quality Index (AQI) of 41, rated "Good." 75.6% of monitored days (276 out of 365) had good air quality in 2025.
What is the main pollutant in Kent County? ▼
The primary pollutant in Kent County is Ozone (O3), which was the main AQI driver on 229 days (63% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Kent County have? ▼
In 2025, Kent County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 122.
Is the air quality in Kent County getting better or worse? ▼
Air quality in Kent County is worsening across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2020 at 81.8% (296 of 362 days). Lowest qualifying Good-day share: 2023 at 62.2% (216 of 348 days).
What does AQI 41 mean for health? ▼
Kent County's median AQI of 41 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Kent County compare to other counties in Delaware? ▼
Kent County has 75.6% good air days. Nearby counties in Delaware: New Castle (64.4% good), Sussex (82.2% good).
What is the 90th percentile AQI in Kent County? ▼
The 90th percentile AQI for Kent County is 62, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 122 (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. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Kent County, Delaware · 2020–2025
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Every figure on PlainAirData 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.