Arapahoe, Colorado Air Quality
Arapahoe County, Colorado (CO)
→ Stableover 10 years
How Arapahoe, Colorado Air Quality Compares
Arapahoe, Colorado's median AQI of 47is 15% worse than the national average of 41. Residents experience an average of 15 unhealthy air days per year, above the national threshold for concern. The primary pollutant of concern is Ground-Level Ozone.
Arapahoe, Colorado Air Quality: The Full Picture
Arapahoe, Colorado (Arapahoe County) holds an AirHistory Air Quality Grade of C (fair, scoring 54 out of 100), built from 10 years of EPA Air Quality System monitoring. Its median AQI rose 2 points between 2014 (45) and 2023 (47), and the five-year median now sits at 46 — 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 351 of 365 monitored days (96% of the year), making it the controlling pollutant for the C grade. The single worst reading logged that year hit an AQI of 136 (Unhealthy for Sensitive Groups), while the 90th-percentile day — the level the dirtiest 10% of days reach — came in at 74.
In 2023, Arapahoe County recorded 239 "Good" air days (65% of the 365 days with valid AQI data), 118 "Moderate" days, and 8 days at "Unhealthy for Sensitive Groups" or above. Over the most recent five years on record, monitors logged 74 days that crossed into "Unhealthy for Sensitive Groups" or worse — about 15 per year.
The decade-long trend is essentially flat, with year-to-year median AQI shifting by less than 0.20 points per year on average. The cleanest year in the record was 2016 (median AQI 44), and the most polluted was 2017 (median AQI 47). Because the data come straight from federally certified EPA monitors, these figures track the Colorado 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).
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 | 47 | 74 | 136 | 239 | 118 | 8 | Ozone |
| 2022 | 46 | 84 | 129 | 237 | 116 | 12 | Ozone |
| 2021 | 46 | 101 | 161 | 220 | 108 | 37 | Ozone |
| 2020 | 46 | 77 | 159 | 243 | 112 | 11 | Ozone |
| 2019 | 47 | 80 | 140 | 222 | 137 | 6 | Ozone |
| 2018 | 46 | 87 | 156 | 227 | 123 | 15 | Ozone |
| 2017 | 47 | 84 | 119 | 221 | 137 | 7 | Ozone |
| 2016 | 44 | 71 | 119 | 261 | 99 | 6 | Ozone |
| 2015 | 45 | 67 | 136 | 257 | 102 | 2 | Ozone |
| 2014 | 45 | 61 | 122 | 261 | 102 | 1 | Ozone |
What This Means for Arapahoe County Residents
Arapahoe, Colorado has received an Air Quality Grade of C (54/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 47 falls in the "Good" range.
The primary pollutant affecting this area is Ground-Level Ozone. Over the past 5 years, this area has averaged 15 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
Arapahoe, Colorado has a current median AQI of 47, which falls in the "Good" range. The area has received an Air Quality Grade of C (54/100) based on 10 years of EPA monitoring data.
Air quality in Arapahoe, Colorado is stable over the past decade. The median AQI has changed by +2 points from 2014 to 2023.
Arapahoe, Colorado averages 15 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 Arapahoe, Colorado is Ground-Level Ozone. This is the dominant contributor to elevated AQI readings in the Arapahoe County area.
Arapahoe, Colorado averages 15 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 47 (Good), outdoor exercise in Arapahoe, Colorado is generally safe year-round. Arapahoe, Colorado averages 15 days per year when athletes should move workouts indoors.