Metro area air quality · 2024
San Diego-Carlsbad, CA
Median AQI 71 (Moderate). 12.8% of monitored days rated Good across this metro's EPA monitoring network.
- 71
- Median AQI
- 12.8%
- Good-air days
- 4
- Unhealthy days
- 1%
- Cleaner than US metros
Aggregated from EPA Air Quality System (2024), 366 monitored days. EPA AQS → · NOAA →
Insights: San Diego-Carlsbad, CA metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 71 over 366 measured days in 2024, which corresponds to a Moderate band and a Very Poor metro-wide health grade. The monitored-day split lands at 47 Good days (13%), 267 Moderate (73%), and 48 Unhealthy-for-Sensitive-Groups (13%). The 90th-percentile AQI finished at 105 while the highest single-day reading hit 161 (Unhealthy). Metro residents averaged roughly 3.9 clean-air days per 30-day window across the reporting year.
Across the 2020–2024 trend window, good days shifted by +14 and the median AQI moved -3 points, which classifies the multi-year trajectory as improving. The metro recorded 4 unhealthy-or-worse days combined, on those days the EPA recommends that sensitive groups limit prolonged outdoor exertion, and many schools and athletic programs adjust outdoor activity accordingly. Metros with comparable AQI profiles include Visalia-Porterville, CA (20.8% good, AQI 71); Bakersfield, CA (20.8% good, AQI 72); El Paso, TX (22.1% good, AQI 67).
Air Quality Summary
Median AQI
71
Moderate
Good Days
12.8%
47 of 366 days
Max AQI
161
Unhealthy
Health Grade
Very Poor
90th pct: 105
AQI Day Breakdown (2024)
Distribution of 366 monitored days across EPA AQI categories.
Good
47
13%
Moderate
267
73%
USG
48
13%
Unhealthy
4
1%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The San Diego-Carlsbad, CA metro area's air quality is rated Very Poor based on 12.8% good air days. There were 4 unhealthy days in 2024 when outdoor activity should be limited.
Air quality is acceptable most days, but 48 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 161. Sensitive groups should monitor real-time conditions at AirNow.gov.
How does the San Diego-Carlsbad, CA metro compare?
How San Diego-Carlsbad, CA compares
5-Year Air Quality Trend
Air quality is improving in the San Diego-Carlsbad, CA metro. Best year: 2023 (61 good days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2020 | 33 | 284 | 14 | 74 | 192 |
| 2021 | 52 | 297 | 0 | 67 | 133 |
| 2022 | 42 | 297 | 1 | 63 | 156 |
| 2023 | 61 | 260 | 0 | 67 | 150 |
| 2024 | 47 | 267 | 4 | 71 | 161 |
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Frequently Asked Questions
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Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2024. The AQS collects ambient air monitoring data from state, local, and tribal monitoring agencies across the United States.
Metrics: Air Quality Index (AQI) is calculated using EPA-standard breakpoints for six criteria pollutants: PM2.5, PM10, Ozone, NO2, CO, and SO2. Median AQI, max AQI, and 90th percentile AQI are computed from daily measurements. Good days percentage reflects days with AQI 0–50.
Coverage: 501 metro areas (Core Based Statistical Areas). Only metros with active monitoring stations are included. Unmonitored areas are not represented.
Read our methodology , how this data is sourced, computed, and verified.
Source: U.S. EPA, AirNow / AQS Air Quality Index readings and pollutant concentrations · 2025