Median AQI
49
Good
Florida · County air quality · 2025
Hillsborough County, Florida
Median AQI 49 (Good). 53.1% of monitored days rated Good, direct from EPA Air Quality System stations.
- 49
- Median AQI
- 53.1%
- Good-air days
- 0
- Unhealthy days
- 8%
- Cleaner than US counties
Hillsborough County's 2025 annual median AQI is 49 (Good), with 53.1% Good days
According to the U.S. EPA Air Quality System, Hillsborough County, Florida posted a 2025 median AQI of 49 (Good) across 365 monitored days, with 53.1% 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
- Hillsborough County's 53.1% Good-day share places it cleaner than 8% of US counties in 2025.
- Closest median-AQI peer
- Adams County (55.1% Good, median AQI 49) is the closest nationwide median-AQI peer to Hillsborough County.
- 2020–2025 trend
- Hillsborough County's floor-qualifying Good-day share is improving from 2020 to 2025 (48.1% → 53.2%).
- Median AQI
- Median AQI: 49
The verdict
According to EPA Air Quality System monitoring data, Hillsborough County's air is good on balance, among the most polluted counties nationally, a median AQI of 49 with 53.1% of 365 monitored days in the Good band, driven mainly by PM2.5.
- 49
- median AQI · Good
- 53.1%
- days rated Good
- PM2.5
- main pollutant
- 8%
- 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
- Hillsborough County's peak single-day AQI fell from 143 to 122 between the 2024 and 2025 EPA annual releases, a change of -21 points.
Data updated August 2026
- Good · 194 d · 53.2%
- Moderate · 169 d · 46.3%
- USG · 2 d · 0.5%
How did Hillsborough County's air break down in 2025?
Across 365 monitored days, 194 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: 49 (Good).
Insights: Hillsborough County, Florida. EPA monitors recorded a median Air Quality Index of 49 across 365 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 194 (53%) fell in the Good band (AQI 0–50), 169 (46%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 63, while the worst single-day peak hit 122 (USG). Residents averaged about 15.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (231 days), Ozone (130 days), PM10 (3 days), NO2 (1 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by +5.1 points and the median AQI moved -3 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 122, usg but never Unhealthy. Nearby counties show comparable readings: Alachua (88.7% good, AQI 37); Baker (69.5% good, AQI 44); Bay (66.4% good, AQI 44); Brevard (91.2% good, AQI 38); Broward (73.4% good, AQI 43); Citrus (71.1% good, AQI 43).
Air Quality Summary
Good Days
53.1%
194 of 365 monitored days
-21.9pp vs 75% target
Max AQI Recorded
122
USG
Health Grade
Moderate
90th-pct AQI 63
Hillsborough County, Good days share 53.1%
National avg
Share of monitored days at AQI 0-50 (Good band).
Hillsborough 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
194
53%
Moderate
169
46%
USG
2
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 Hillsborough County.
- PM2.5 · 231 days · 63.3%
- Ozone · 130 days · 35.6%
- PM10 · 3 days · 0.8%
- NO₂ · 1 days · 0.3%
Health Impact Assessment
Moderate
Hillsborough County's air quality is rated Moderate based on 53.1% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 53.1% of monitored days in 2025, with a median AQI of 49. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 231 of 365 monitored days.
5-Year Air Quality Trend
Air quality is improving in Hillsborough County. Highest Good-day share: 2025 (53.2%, 194 of 365 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 176 | 187 | 3 | 0 | 52 | 112 |
| 2021 | 167 | 197 | 1 | 0 | 51 | 129 |
| 2022 | 175 | 189 | 1 | 0 | 51 | 126 |
| 2023 | 156 | 206 | 3 | 0 | 51 | 114 |
| 2024 | 190 | 168 | 4 | 0 | 50 | 143 |
| 2025 | 194 | 169 | 2 | 0 | 49 | 122 |
How does Hillsborough County compare?
How Hillsborough County compares
Good-day share worse than typical
Hillsborough County 53.1%
Adams County, Colorado 55.1%
Typical US county 76.0%
Median AQI worse than typical
Hillsborough County 49
Adams County, Colorado 49
Typical US county 39
Unhealthy days / yr better than typical
Hillsborough County 0
Adams County, Colorado 0
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Hillsborough County (49), not geographic neighbors.
Adams County, Colorado
Median AQI 49 · 55.1% Good-day share
Albany County, Wyoming
Median AQI 49 · 55.6% Good-day share
Black Hawk County, Iowa
Median AQI 49 · 53.4% Good-day share
Davidson County, Tennessee
Median AQI 49 · 52.9% Good-day share
Eddy County, New Mexico
Median AQI 49 · 53.7% Good-day share
Fulton County, Georgia
Median AQI 49 · 54.3% Good-day share
Same primary pollutant: PM2.5
PM2.5 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).
Stark County, Ohio
53.1% Good-day share · median AQI 49
Arkansas County, Arkansas
52.9% Good-day share · median AQI 48
Plumas County, California
52.9% Good-day share · median AQI 45
Jefferson County, Ohio
53.4% Good-day share · median AQI 49
Walker County, Georgia
53.4% Good-day share · median AQI 48
Ottawa County, Oklahoma
53.7% Good-day share · median AQI 49
Florida counties on the map
Geographic containment only, other monitored counties in Florida, independent of AQI or pollutant match.
What Hillsborough County's air means for you
The air here stays in the breathable range year-round, with PM2.5 the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 49 means for exposure. Health guidance
- See how Hillsborough County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Hillsborough County with its Florida neighbours before drawing a conclusion about the region. All of Florida
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 Hillsborough County, Florida? ▼
Hillsborough County has a median Air Quality Index (AQI) of 49, rated "Good." 53.1% of monitored days (194 out of 365) had good air quality in 2025.
What is the main pollutant in Hillsborough County? ▼
The primary pollutant in Hillsborough County is Fine Particles (PM2.5), which was the main AQI driver on 231 days (63% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Hillsborough County have? ▼
In 2025, Hillsborough County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 122.
Is the air quality in Hillsborough County getting better or worse? ▼
Air quality in Hillsborough County is improving across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2025 at 53.2% (194 of 365 days). Lowest qualifying Good-day share: 2023 at 42.7% (156 of 365 days).
What does AQI 49 mean for health? ▼
Hillsborough County's median AQI of 49 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Hillsborough County compare to other counties in Florida? ▼
Hillsborough County has 53.1% good air days. Nearby counties in Florida: Alachua (88.7% good), Baker (69.5% good), Bay (66.4% good), Brevard (91.2% good), Broward (73.4% good), Citrus (71.1% good).
What is the 90th percentile AQI in Hillsborough County? ▼
The 90th percentile AQI for Hillsborough County is 63, 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 Hillsborough County, Florida · 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.