Glenn, California Air Quality
Glenn County, California (CA)
↓ Improvingover 10 years
How Glenn, California Air Quality Compares
Glenn, California's median AQI of 41is 0% better than the national average of 41. The area averages 9 unhealthy air days per year. The primary pollutant of concern is Ground-Level Ozone.
Glenn, California Air Quality: The Full Picture
Glenn, California (Glenn County) holds an AirHistory Air Quality Grade of C (fair, scoring 64 out of 100), built from 10 years of EPA Air Quality System monitoring. Its median AQI fell 3 points between 2014 (44) and 2023 (41), and the five-year median now sits at 43 — inside the "Good" band on the EPA scale.
The pollutant driving most of the area's AQI readings is Ground-Level Ozone. In 2023, it set the daily AQI on 228 of 363 monitored days (63% of the year), making it the controlling pollutant for the C grade. The single worst reading logged that year hit an AQI of 97 (Moderate), while the 90th-percentile day — the level the dirtiest 10% of days reach — came in at 58.
In 2023, Glenn County recorded 273 "Good" air days (75% of the 363 days with valid AQI data), 90 "Moderate" days, and 0 days at "Unhealthy for Sensitive Groups" or above. Over the most recent five years on record, monitors logged 45 days that crossed into "Unhealthy for Sensitive Groups" or worse — about 9 per year.
The decade-long trend is improving: median AQI has been dropping by roughly 0.50 points per year. The cleanest year in the record was 2018 (median AQI 39), and the most polluted was 2016 (median AQI 48). Because the data come straight from federally certified EPA monitors, these figures track the California county the monitors physically sit in rather than a city boundary.
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10-Year AQI Trend
The solid line shows the median AQI each year. The dashed line shows the 90th percentile (worst 10% of days). This area has seen measurable air quality improvement over the decade.
Air Quality Day Breakdown
Number of days per year in each EPA AQI category. Green = Good (AQI 0-50), Yellow = Moderate (51-100), Orange = Unhealthy for Sensitive Groups (101-150), Red = Unhealthy or worse (151+).
Year-by-Year Data
| Year | Median AQI | 90th Pct | Max AQI | Good Days | Moderate | Unhealthy+ | Pollutant |
|---|---|---|---|---|---|---|---|
| 2023 | 41 | 58 | 97 | 273 | 90 | 0 | Ozone |
| 2022 | 42 | 61 | 104 | 264 | 95 | 1 | Ozone |
| 2021 | 42 | 65 | 192 | 244 | 106 | 15 | Ozone |
| 2020 | 46 | 84 | 221 | 200 | 135 | 29 | PM2.5 |
| 2019 | 42 | 58 | 86 | 274 | 88 | 0 | Ozone |
| 2018 | 39 | 71 | 255 | 242 | 105 | 16 | PM2.5 |
| 2017 | 46 | 63 | 150 | 231 | 127 | 7 | PM2.5 |
| 2016 | 48 | 64 | 92 | 194 | 168 | 0 | PM2.5 |
| 2015 | 46 | 68 | 93 | 221 | 144 | 0 | Ozone |
| 2014 | 44 | 61 | 105 | 244 | 120 | 1 | Ozone |
What This Means for Glenn County Residents
Glenn, California has received an Air Quality Grade of C (64/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 41 falls in the "Good" range.
Encouragingly, air quality here has been improving, with the median AQI dropping by 3 points over the monitoring period. This trend suggests continued investment in emission controls and cleaner energy.
The primary pollutant affecting this area is Ground-Level Ozone. Over the past 5 years, this area has averaged 9 unhealthy air quality days per year, days when sensitive groups (children, elderly, those with respiratory conditions) should limit outdoor activity. The American Lung Association's State of the Air report provides additional context on long-term health risks from air pollution exposure.
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Frequently Asked Questions
Glenn, California has a current median AQI of 41, which falls in the "Good" range. The area has received an Air Quality Grade of C (64/100) based on 10 years of EPA monitoring data.
Air quality in Glenn, California is improving over the past decade. The median AQI has changed by -3 points from 2014 to 2023.
Glenn, California averages 9 unhealthy air quality days per year over the past 5 years. On these days, sensitive groups including children, the elderly, and those with respiratory conditions should limit outdoor activity.
The primary pollutant affecting Glenn, California is Ground-Level Ozone. This is the dominant contributor to elevated AQI readings in the Glenn County area.
Glenn, California averages 9 unhealthy air days per year. Asthma patients should monitor daily AQI readings and limit outdoor activity when AQI exceeds 100. The primary pollutant is Ground-Level Ozone, which is a known asthma trigger.
With a median AQI of 41 (Good), outdoor exercise in Glenn, California is generally safe year-round. Glenn, California averages 9 days per year when athletes should move workouts indoors.