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AirHistory

What Is the Air Quality in Prince William, Virginia?

Prince William, Virginia has an Air Quality Grade of C (fair) with a 5-year median AQI of 35. The dominant pollutant is Ground-Level Ozone, and air quality has been worsening over the past decade.

Prince William, Virginia Air Quality Snapshot

Air Quality GradeC63/100
5-Year Median AQI35 (Good)
Most Recent Median AQI (2023)37 (Good)
Dominant PollutantGround-Level Ozone
10-Year TrendWorsening (+0.70 AQI/yr)
Unhealthy Days (last 5 yr)4
National Rank (cleanest = #1)#245 of 1,020 (24th cleanest percentile)
Virginia Rank#14 of 32

What Does the C Grade Mean?

Prince William, Virginia earns a C — air quality is fair, but not great. With a 5-year median AQI of 35, the city sees a meaningful number of "Moderate" days each year, when the EPA flags air as a concern for unusually sensitive people.

Prince William, Virginia's 5-year median AQI of 35 is 6 points below the national average of 41 — meaningfully cleaner than the typical U.S. metro tracked here. Within Virginia, Prince William, Virginia's air quality is roughly typical for the state, where the average city posts a 5-year median AQI of 33.

For context within Virginia: Alexandria City, Virginia currently holds the state's cleanest grade (A, AQI 6), while Richmond City, Virginia sits at the bottom (C, AQI 42).

What's in Prince William, Virginia's Air?

The dominant pollutant in Prince William, Virginia is Ground-Level Ozone. Ground-level ozone forms when sunlight reacts with vehicle exhaust and industrial emissions. It is worst on hot, sunny, stagnant summer days. Ozone irritates the lungs, triggers asthma attacks, and reduces lung function — even healthy adults can feel chest tightness and shortness of breath after exercising in elevated ozone.

Days by Dominant Pollutant (2023)

PollutantDays as DominantShare of Year
Ground-Level Ozone36199%
Nitrogen Dioxide41%

Is the Air Getting Better or Worse?

Air quality in Prince William, Virginia has been getting worse over the past decade, with median AQI climbing by roughly 0.7 points per year. That bucks the national trend of broad improvement, and most often reflects either growing wildfire smoke exposure (particularly across the West) or rising local emissions from population and freight growth.

In 2014, Prince William, Virginia posted a median AQI of 30. By 2023 that figure was 37 — a rise of 7 AQI points dirtier across 10 years of EPA records.

Year-by-Year AQI in Prince William, Virginia

YearMedian AQIGood DaysUnhealthy DaysDominant Pollutant
2014303321Ozone
2015303300Ozone
2016313233Ozone
2017343330Ozone
2018323160Ozone
2019363470Ozone
2020323570Ozone
2021353331Ozone
2022353370Ozone
2023373293Ozone

Health Context for Prince William, Virginia

Across the past five years, this area has logged just 4 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 1 days per year, or roughly one every other month. That is a low count by national standards.

Healthy adults can continue normal outdoor activity in most weather, but should pay attention to AQI alerts during the worst pollution windows. People with asthma, heart disease, or pregnancy should reduce prolonged or intense outdoor exertion on flagged days, and consider running an indoor HEPA air cleaner during peak season. Because ozone peaks in the afternoon on hot sunny days, plan outdoor exercise for early morning or after sunset on bad-air days.

How This Grade Is Calculated

The AirHistory Air Quality Grade combines four signals: the 5-year median AQI (40% of the score), the 10-year trend direction (30%), the count of unhealthy days per year (20%), and the dominant pollutant type (10%). All four come directly from the EPA Air Quality System (AQS), which aggregates readings from federally certified monitors. Read the full methodology.

Prince William, Virginia has an Air Quality Grade of C (fair) with a 5-year median AQI of 35. The dominant pollutant is Ground-Level Ozone, and air quality has been worsening over the past decade.

This answer pulls from the EPA Air Quality System (AQS), the authoritative federal source for U.S. air quality and pollution monitoring. The headline number above is the direct answer; what follows is the additional context most readers need to use the answer for a real decision rather than just a fact lookup.

A practical caveat: the headline answer above reflects the most recent the EPA Air Quality System (AQS) vintage; underlying data is often revised for months after first publication, and the right reference for any specific decision is whichever vintage is current at the time of the decision. The as-of date is stamped on every page.

Source: EPA Outdoor Air Quality Data, 2026.