Loudoun, Virginia Air Quality
Loudoun County, Virginia (VA)
→ Stableover 10 years
How Loudoun, Virginia Air Quality Compares
Loudoun, Virginia's median AQI of 39is 5% better than the national average of 41. The area averages 2 unhealthy air days per year. The primary pollutant of concern is Ground-Level Ozone.
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 | 39 | 58 | 167 | 306 | 54 | 4 | Ozone |
| 2022 | 37 | 50 | 112 | 328 | 34 | 2 | Ozone |
| 2021 | 37 | 54 | 122 | 308 | 55 | 1 | Ozone |
| 2020 | 34 | 48 | 108 | 339 | 26 | 1 | Ozone |
| 2019 | 38 | 54 | 112 | 286 | 50 | 1 | Ozone |
| 2018 | 35 | 54 | 93 | 313 | 52 | 0 | Ozone |
| 2017 | 38 | 57 | 100 | 297 | 68 | 0 | Ozone |
| 2016 | 36 | 58 | 112 | 302 | 63 | 1 | Ozone |
| 2015 | 38 | 60 | 115 | 294 | 63 | 4 | Ozone |
| 2014 | 40 | 58 | 105 | 285 | 69 | 1 | Ozone |
What This Means for Loudoun County Residents
Loudoun, Virginia has received an Air Quality Grade of B (68/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 39 falls in the "Good" range.
The primary pollutant affecting this area is Ground-Level Ozone. Over the past 5 years, this area has averaged 2 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.
Related Cities in Virginia
AQI: 44 · Grade: C
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AQI: 39 · Grade: B
AQI: 40 · Grade: B
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AQI: 40 · Grade: B
AQI: 41 · Grade: B
Frequently Asked Questions
Loudoun, Virginia has a current median AQI of 39, which falls in the "Good" range. The area has received an Air Quality Grade of B (68/100) based on 10 years of EPA monitoring data.
Air quality in Loudoun, Virginia is stable over the past decade. The median AQI has changed by -1 points from 2014 to 2023.
Loudoun, Virginia averages 2 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 Loudoun, Virginia is Ground-Level Ozone. This is the dominant contributor to elevated AQI readings in the Loudoun County area.
Loudoun, Virginia averages 2 unhealthy air days per year. This is relatively low, making it a reasonable choice for asthma sufferers. The primary pollutant is Ground-Level Ozone, which is a known asthma trigger.
With a median AQI of 39 (Good), outdoor exercise in Loudoun, Virginia is generally safe year-round. Loudoun, Virginia averages 2 days per year when athletes should move workouts indoors.
For this entity, the underlying data on this page comes from the EPA Air Quality System (AQS). The breakdown above is the federal record; the paragraphs below add the per-entity context that makes the headline numbers usable for a real decision rather than just a data lookup.
The methodology behind every numeric value on this page is publicly documented on the the EPA Air Quality System (AQS) portal and described in detail on this site’s methodology page. Refresh cadence varies by underlying series; the page surfaces the as-of date for each number so readers can trace any figure back to the source release.
For readers using this page as a decision input, the related-entity pages elsewhere on the site provide the comparison set. The most useful comparison for this entity is typically a peer within U.S. counties and states with similar size, similar exposure, or similar geography — not the national-level summary alone.