Arizona · County air quality · 2025
Santa Cruz County, Arizona
Median AQI 49 (Good). 52.2% of monitored days rated Good, direct from EPA Air Quality System stations.
- 49
- Median AQI
- 52.2%
- Good-air days
- 1
- Unhealthy days
- 8%
- Cleaner than US counties
Santa Cruz County's 2025 annual median AQI is 49 (Good), with 52.2% Good days
According to the U.S. EPA Air Quality System, Santa Cruz County, Arizona posted a 2025 median AQI of 49 (Good) across 364 monitored days, with 52.2% rated Good and 1 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Santa Cruz County's 52.2% 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 Santa Cruz County.
- 2020–2025 trend
- Santa Cruz County's floor-qualifying Good-day share is worsening from 2020 to 2025 (57.8% → 52.2%).
- Median AQI
- Median AQI: 49
According to the 2025 EPA AQS county release on PlainAirData, Santa Cruz County, Arizona ranks #866 of 951 by median AQI (49) and #879 by good-day share (52.2%). Ponce County, Puerto Rico is #1 of 951 by median AQI (3, 91.4% Good days) at good-day-share #159 ≠ largest of 7 at 100.0% Good days #1 by good-day share (100.0%, median AQI 9) at median-AQI #7.
Annual release change
What changed in the 2025 EPA annual release
- Santa Cruz County's peak single-day AQI fell from 494 to 187 between the 2024 and 2025 EPA annual releases, a change of -307 points.
- Santa Cruz County's Good-day share fell from 59.0% to 52.2% between the 2024 and 2025 EPA annual releases, a change of -6.8 percentage points.
- Santa Cruz County's median AQI rose from 43 to 49 between the 2024 and 2025 EPA annual releases, a change of +6 points.
- Santa Cruz County's Unhealthy-category days rose from 0 to 1 between the 2024 and 2025 EPA annual releases, a change of +1 days.
Data updated August 2026
- Good · 190 d · 52.2%
- Moderate · 171 d · 47.0%
- USG · 2 d · 0.5%
- Unhealthy · 1 d · 0.3%
How did Santa Cruz County's air break down in 2025?
Across 364 monitored days, 190 fell in the Good band (AQI 0–50) and 1 reached Unhealthy or worse. The worst single day peaked at AQI 187 (Unhealthy).
EPA AQS →Share of monitored days at AQI 0-50 (Good band).
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
Where Santa Cruz County sits nationally
COUNT-derived placement among 951 US counties with at least 100 monitored days in 2025. Santa Cruz County's Good-day share is 52.2% - cleaner than 8% of that comparison set.
Santa Cruz County Good-day share vs. every US county
Share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release
52.2% 8th percentile higher than 8% of 951 US counties
Each bar is a band; taller bars hold more US counties. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source U.S. Environmental Protection Agency, Air Quality System (AQS) · 2025
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Santa Cruz County.
- PM2.5 · 289 days · 79.4%
- PM10 · 75 days · 20.6%
2024 daily-monitor rhythm in Santa Cruz County
Month-by-month median AQI from EPA day-level county monitors (361 reported days in 2024). Dec posted the highest typical readings (median AQI 76, peak 111); Apr was cleanest at median 33. Summer months (Jun–Aug) averaged median AQI 37 vs 61 in Dec–Feb. 1 day crossed Unhealthy (AQI >150) at least once that year.
Five-year seasonal record
EPA day-level county files · 2020–20241,796 daily readings show a recurring local pattern: Dec has the highest matched-month median AQI (66), while Jul is lowest (31). Each cell is that month’s median daily AQI, not a current-air forecast.
Lower AQI is better. The colors summarize EPA AQI bands; gaps mean the county had no day-level record for that month.
Health Impact Assessment
Santa Cruz County's air quality is rated Moderate based on 52.2% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 2 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 187. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is PM2.5, driving AQI on 289 of 364 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Santa Cruz County. Highest Good-day share: 2023 (74.0%, 265 of 358 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 208 | 147 | 4 | 1 | 44 | 170 |
| 2021 | 169 | 189 | 1 | 1 | 52 | 171 |
| 2022 | 220 | 136 | 1 | 0 | 43 | 138 |
| 2023 | 265 | 92 | 1 | 0 | 37 | 145 |
| 2024 | 213 | 139 | 8 | 0 | 43 | 494 |
| 2025 | 190 | 171 | 2 | 1 | 49 | 187 |
How does Santa Cruz County compare?
How Santa Cruz County compares
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 Santa Cruz County, Arizona · 2020–2025
Download this county's annual AQI row as CSV , with the same EPA fields and denominator shown on this page.
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.