Metro area air quality · 2025
Chico, CA
Median AQI 46 (Good). 65.2% of monitored days rated Good across this metro's EPA monitoring network.
- 46
- Median AQI
- 65.2%
- Good-air days
- 0
- Unhealthy days
- 34%
- Cleaner than US metros
Chico, CA posted a 2025 median AQI of 46 (Good) with 65.2% Good days
According to the U.S. EPA Air Quality System, the Chico, CA CBSA recorded a median AQI of 46 across 365 monitored days in 2025, with 65.2% rated Good and 0 unhealthy or worse. This is an annual metro comparison, not a live advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US metros
- The Chico, CA CBSA's 65.2% Good-day share places it cleaner than 34% of US metros in 2025.
- Closest median-AQI peer
- Albany, GA (57.3% Good, median AQI 46) is the closest nationwide median-AQI peer to Chico, CA.
- 2020–2025 Good-day shift
- Chico, CA's Good-day share moved +21.8 points from 2020 to 2025 (median AQI -8).
- Median AQI
- Median AQI: 46
Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →
The verdict
Chico, CA's median AQI 46 is in the upper (dirtier) CBSA tercile on this site. On the EPA scale the metro runs good, more polluted than the median US metro, with a median AQI of 46 and 65.2% of 365 monitored days in the Good band.
- 46
- median AQI · Good
- 65.2%
- days rated Good
- 34%
- cleaner than US metros
- 96
- worst single reading
No day crossed into the Unhealthy tier across the metro's monitors in 2025.
Annual release change
What changed in the 2025 EPA annual release
- Chico, CA metro's peak single-day AQI fell from 213 to 96 between the 2024 and 2025 EPA annual releases, a change of -117 points.
- Chico, CA metro's Good-day share rose from 63.3% to 65.2% between the 2024 and 2025 EPA annual releases, a change of +1.9 percentage points.
- Chico, CA metro's Unhealthy-category days fell from 1 to 0 between the 2024 and 2025 EPA annual releases, a change of -1 days.
Chico, CA's median AQI 46 is in the upper (dirtier) CBSA tercile on this site. Signature read: median AQI 46 (high tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 46 over 365 measured days in 2025 (Good / Moderate). The monitored-day split lands at 238 Good (65%), 127 Moderate (35%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 61; the highest single-day reading hit 96 (Moderate).
Across 2020–2025, Good-day share shifted +21.8 points and median AQI moved -8 (improving). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Albany, GA (57.3% good, AQI 46); Athens-Clarke County, GA (57.8% good, AQI 46); Brookings, SD (58.6% good, AQI 46).
Air Quality Summary
Median AQI
46
Good
Good Days
65.2%
238 of 365 days
Max AQI
96
Moderate
Health Grade
Moderate
90th pct: 61
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
238
65%
Moderate
127
35%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The Chico, CA metro area's air quality is rated Moderate based on 65.2% good air days. No unhealthy air days were recorded in 2025.
Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.
How does the Chico, CA metro compare?
How Chico, CA compares
5-Year Air Quality Trend
Air quality is improving in the Chico, CA metro. Highest Good-day share: 2025 (65.2%, 238 of 365 monitored days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2020 | 149 | 178 | 16 | 54 | 508 |
| 2021 | 160 | 174 | 10 | 53 | 257 |
| 2022 | 191 | 171 | 0 | 50 | 119 |
| 2023 | 191 | 174 | 0 | 50 | 100 |
| 2024 | 231 | 133 | 1 | 46 | 213 |
| 2025 | 238 | 127 | 0 | 46 | 96 |
Metros with a similar median AQI
CBSA peers nationwide whose annual median AQI sits near Chico, CA (46).
Albany, GA
Median AQI 46 · 57.3% Good-day share
Athens-Clarke County, GA
Median AQI 46 · 57.8% Good-day share
Brookings, SD
Median AQI 46 · 58.6% Good-day share
Colorado Springs, CO
Median AQI 46 · 68.2% Good-day share
Davenport-Moline-Rock Island, IA-IL
Median AQI 46 · 56.7% Good-day share
Eugene, OR
Median AQI 46 · 56.4% Good-day share
Metros with similar unhealthy-day exposure
A second relationship type: metros whose unhealthy-or-worse day count is closest to Chico, CA's 0 (independent of median AQI).
Aberdeen, SD
0 unhealthy-or-worse days · median AQI 27
Aberdeen, WA
0 unhealthy-or-worse days · median AQI 22
Adrian, MI
0 unhealthy-or-worse days · median AQI 41
Akron, OH
0 unhealthy-or-worse days · median AQI 45
Albany, OR
0 unhealthy-or-worse days · median AQI 27
Albany-Schenectady-Troy, NY
0 unhealthy-or-worse days · median AQI 41
Frequently Asked Questions
What does AQI 46 mean for health? ▼
How many unhealthy air days does Chico, CA have? ▼
What is the air quality in the Chico, CA metro area? ▼
Is air quality in Chico, CA getting better or worse? ▼
How does Chico, CA compare to other metro areas? ▼
What is the 90th percentile AQI for Chico, CA? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Chico, CA, 2025. See our methodology for how AQI, median, and coverage figures are computed.
Read our methodology , how this data is sourced, computed, and verified.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary, Chico, CA · 2020–2025