EnviroNearby

Fairfax County, Virginia air quality history

Daily Air Quality Index summaries from EPA monitors in Fairfax, Virginia, 1980–2025.

78%
Good days in 2025
42
Median daily AQI, 2025
1
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Fairfax, Virginia on 365 days. 284 of those days (78%) were in the Good range, and the median daily AQI was 42. That median is higher than the typical monitored county in Virginia (median 37 across 25 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 187 days. Across the years with fuller monitoring, the share of Good days rose: an average of 50% in 1980–1982 versus 70% in 2023–2025.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Share of monitored days in each AQI category, by year0%25%50%75%100%1980: Good 172 of 366 days1980: Moderate 144 of 366 days1980: Unhealthy for Sensitive Groups 28 of 366 days1980: Unhealthy 18 of 366 days1980: Very Unhealthy 4 of 366 days19801981: Good 192 of 365 days1981: Moderate 132 of 365 days1981: Unhealthy for Sensitive Groups 26 of 365 days1981: Unhealthy 13 of 365 days1981: Very Unhealthy 2 of 365 days1982: Good 187 of 365 days1982: Moderate 129 of 365 days1982: Unhealthy for Sensitive Groups 30 of 365 days1982: Unhealthy 17 of 365 days1982: Very Unhealthy 2 of 365 days1983: Good 153 of 365 days1983: Moderate 130 of 365 days1983: Unhealthy for Sensitive Groups 29 of 365 days1983: Unhealthy 30 of 365 days1983: Very Unhealthy 23 of 365 days1984: Good 137 of 366 days1984: Moderate 183 of 366 days1984: Unhealthy for Sensitive Groups 29 of 366 days1984: Unhealthy 13 of 366 days1984: Very Unhealthy 4 of 366 days1985: Good 158 of 365 days1985: Moderate 136 of 365 days1985: Unhealthy for Sensitive Groups 50 of 365 days1985: Unhealthy 18 of 365 days1985: Very Unhealthy 3 of 365 days19851986: Good 182 of 365 days1986: Moderate 132 of 365 days1986: Unhealthy for Sensitive Groups 28 of 365 days1986: Unhealthy 20 of 365 days1986: Very Unhealthy 3 of 365 days1987: Good 150 of 365 days1987: Moderate 148 of 365 days1987: Unhealthy for Sensitive Groups 28 of 365 days1987: Unhealthy 28 of 365 days1987: Very Unhealthy 11 of 365 days1988: Good 185 of 366 days1988: Moderate 111 of 366 days1988: Unhealthy for Sensitive Groups 28 of 366 days1988: Unhealthy 23 of 366 days1988: Very Unhealthy 19 of 366 days1989: Good 160 of 365 days1989: Moderate 140 of 365 days1989: Unhealthy for Sensitive Groups 47 of 365 days1989: Unhealthy 16 of 365 days1989: Very Unhealthy 2 of 365 days1990: Good 149 of 365 days1990: Moderate 172 of 365 days1990: Unhealthy for Sensitive Groups 35 of 365 days1990: Unhealthy 6 of 365 days1990: Very Unhealthy 3 of 365 days19901991: Good 117 of 365 days1991: Moderate 171 of 365 days1991: Unhealthy for Sensitive Groups 43 of 365 days1991: Unhealthy 28 of 365 days1991: Very Unhealthy 6 of 365 days1992: Good 175 of 366 days1992: Moderate 154 of 366 days1992: Unhealthy for Sensitive Groups 27 of 366 days1992: Unhealthy 10 of 366 days1993: Good 174 of 365 days1993: Moderate 120 of 365 days1993: Unhealthy for Sensitive Groups 41 of 365 days1993: Unhealthy 27 of 365 days1993: Very Unhealthy 3 of 365 days1994: Good 188 of 365 days1994: Moderate 127 of 365 days1994: Unhealthy for Sensitive Groups 36 of 365 days1994: Unhealthy 14 of 365 days1995: Good 226 of 365 days1995: Moderate 91 of 365 days1995: Unhealthy for Sensitive Groups 26 of 365 days1995: Unhealthy 18 of 365 days1995: Very Unhealthy 4 of 365 days19951996: Good 227 of 366 days1996: Moderate 101 of 366 days1996: Unhealthy for Sensitive Groups 29 of 366 days1996: Unhealthy 9 of 366 days1997: Good 239 of 365 days1997: Moderate 85 of 365 days1997: Unhealthy for Sensitive Groups 27 of 365 days1997: Unhealthy 11 of 365 days1997: Very Unhealthy 3 of 365 days1998: Good 227 of 365 days1998: Moderate 78 of 365 days1998: Unhealthy for Sensitive Groups 35 of 365 days1998: Unhealthy 22 of 365 days1998: Very Unhealthy 3 of 365 days1999: Good 143 of 365 days1999: Moderate 165 of 365 days1999: Unhealthy for Sensitive Groups 36 of 365 days1999: Unhealthy 20 of 365 days1999: Very Unhealthy 1 of 365 days2000: Good 108 of 366 days2000: Moderate 229 of 366 days2000: Unhealthy for Sensitive Groups 25 of 366 days2000: Unhealthy 3 of 366 days2000: Very Unhealthy 1 of 366 days20002001: Good 101 of 365 days2001: Moderate 215 of 365 days2001: Unhealthy for Sensitive Groups 35 of 365 days2001: Unhealthy 13 of 365 days2001: Very Unhealthy 1 of 365 days2002: Good 109 of 365 days2002: Moderate 198 of 365 days2002: Unhealthy for Sensitive Groups 34 of 365 days2002: Unhealthy 17 of 365 days2002: Very Unhealthy 7 of 365 days2003: Good 107 of 365 days2003: Moderate 231 of 365 days2003: Unhealthy for Sensitive Groups 22 of 365 days2003: Unhealthy 4 of 365 days2003: Very Unhealthy 1 of 365 days2004: Good 108 of 366 days2004: Moderate 232 of 366 days2004: Unhealthy for Sensitive Groups 20 of 366 days2004: Unhealthy 4 of 366 days2004: Very Unhealthy 2 of 366 days2005: Good 115 of 365 days2005: Moderate 212 of 365 days2005: Unhealthy for Sensitive Groups 27 of 365 days2005: Unhealthy 11 of 365 days20052006: Good 134 of 365 days2006: Moderate 195 of 365 days2006: Unhealthy for Sensitive Groups 26 of 365 days2006: Unhealthy 8 of 365 days2006: Very Unhealthy 2 of 365 days2007: Good 116 of 365 days2007: Moderate 207 of 365 days2007: Unhealthy for Sensitive Groups 37 of 365 days2007: Unhealthy 5 of 365 days2008: Good 152 of 366 days2008: Moderate 192 of 366 days2008: Unhealthy for Sensitive Groups 19 of 366 days2008: Unhealthy 3 of 366 days2009: Good 178 of 365 days2009: Moderate 182 of 365 days2009: Unhealthy for Sensitive Groups 5 of 365 days2010: Good 172 of 365 days2010: Moderate 170 of 365 days2010: Unhealthy for Sensitive Groups 17 of 365 days2010: Unhealthy 6 of 365 days20102011: Good 179 of 360 days2011: Moderate 165 of 360 days2011: Unhealthy for Sensitive Groups 12 of 360 days2011: Unhealthy 4 of 360 days2012: Good 190 of 364 days2012: Moderate 153 of 364 days2012: Unhealthy for Sensitive Groups 18 of 364 days2012: Unhealthy 2 of 364 days2012: Very Unhealthy 1 of 364 days2013: Good 220 of 365 days2013: Moderate 144 of 365 days2013: Unhealthy for Sensitive Groups 1 of 365 days2014: Good 219 of 363 days2014: Moderate 143 of 363 days2014: Unhealthy for Sensitive Groups 1 of 363 days2015: Good 217 of 365 days2015: Moderate 144 of 365 days2015: Unhealthy for Sensitive Groups 4 of 365 days20152016: Good 228 of 366 days2016: Moderate 132 of 366 days2016: Unhealthy for Sensitive Groups 6 of 366 days2017: Good 206 of 365 days2017: Moderate 158 of 365 days2017: Unhealthy for Sensitive Groups 1 of 365 days2018: Good 203 of 365 days2018: Moderate 161 of 365 days2018: Unhealthy for Sensitive Groups 1 of 365 days2019: Good 192 of 365 days2019: Moderate 171 of 365 days2019: Unhealthy for Sensitive Groups 2 of 365 days2020: Good 236 of 366 days2020: Moderate 130 of 366 days20202021: Good 208 of 365 days2021: Moderate 153 of 365 days2021: Unhealthy for Sensitive Groups 4 of 365 days2022: Good 232 of 365 days2022: Moderate 133 of 365 days2023: Good 217 of 365 days2023: Moderate 138 of 365 days2023: Unhealthy for Sensitive Groups 7 of 365 days2023: Unhealthy 2 of 365 days2023: Very Unhealthy 1 of 365 days2024: Good 263 of 366 days2024: Moderate 100 of 366 days2024: Unhealthy for Sensitive Groups 3 of 366 days2025: Good 284 of 365 days2025: Moderate 80 of 365 days2025: Unhealthy for Sensitive Groups 1 of 365 days2025
  • Good
  • Moderate
  • Unhealthy for Sensitive Groups
  • Unhealthy
  • Very Unhealthy
  • Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median and 90th-percentile daily AQI, by year0501001502001980: 90th percentile AQI 1221981: 90th percentile AQI 1121982: 90th percentile AQI 1121983: 90th percentile AQI 1851984: 90th percentile AQI 1121985: 90th percentile AQI 1331986: 90th percentile AQI 1261987: 90th percentile AQI 1541988: 90th percentile AQI 1691989: 90th percentile AQI 1191990: 90th percentile AQI 1041991: 90th percentile AQI 1431992: 90th percentile AQI 1011993: 90th percentile AQI 1331994: 90th percentile AQI 1121995: 90th percentile AQI 1191996: 90th percentile AQI 1011997: 90th percentile AQI 1011998: 90th percentile AQI 1291999: 90th percentile AQI 1292000: 90th percentile AQI 972001: 90th percentile AQI 1102002: 90th percentile AQI 1332003: 90th percentile AQI 932004: 90th percentile AQI 932005: 90th percentile AQI 1012006: 90th percentile AQI 1002007: 90th percentile AQI 1052008: 90th percentile AQI 872009: 90th percentile AQI 742010: 90th percentile AQI 872011: 90th percentile AQI 772012: 90th percentile AQI 842013: 90th percentile AQI 622014: 90th percentile AQI 612015: 90th percentile AQI 662016: 90th percentile AQI 642017: 90th percentile AQI 612018: 90th percentile AQI 662019: 90th percentile AQI 642020: 90th percentile AQI 582021: 90th percentile AQI 652022: 90th percentile AQI 582023: 90th percentile AQI 692024: 90th percentile AQI 612025: 90th percentile AQI 591980: Median AQI 521981: Median AQI 481982: Median AQI 501983: Median AQI 541984: Median AQI 581985: Median AQI 521986: Median AQI 511987: Median AQI 551988: Median AQI 501989: Median AQI 541990: Median AQI 551991: Median AQI 621992: Median AQI 521993: Median AQI 521994: Median AQI 491995: Median AQI 451996: Median AQI 451997: Median AQI 441998: Median AQI 461999: Median AQI 562000: Median AQI 592001: Median AQI 582002: Median AQI 572003: Median AQI 572004: Median AQI 582005: Median AQI 582006: Median AQI 552007: Median AQI 562008: Median AQI 532009: Median AQI 512010: Median AQI 522011: Median AQI 512012: Median AQI 492013: Median AQI 462014: Median AQI 462015: Median AQI 462016: Median AQI 442017: Median AQI 492018: Median AQI 482019: Median AQI 492020: Median AQI 442021: Median AQI 472022: Median AQI 472023: Median AQI 462024: Median AQI 422025: Median AQI 421980198519901995200020052010201520202025
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2025

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

PollutantDays as main pollutantShare of monitored days
Ozone18751%
Fine particles (PM2.5)14841%
Nitrogen dioxide (NO₂)308%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253652848010004259124Ozone
202436626310030004261112Ozone
202336521713872104669222PM2.5
20223652321330000475887PM2.5
202136520815340004765129PM2.5
202036623613000004458100PM2.5
201936519217120004964105PM2.5
201836520316110004866101PM2.5
201736520615810004961105PM2.5
201636622813260004464129PM2.5
201536521714440004666119PM2.5
201436321914310004661105PM2.5
201336522014410004662119PM2.5
2012364190153182104984201PM2.5
2011360179165124005177185PM2.5
2010365172170176005287174PM2.5
200936517818250005174133PM2.5
2008366152192193005387192PM2.5
20073651162073750056105174PM2.5
20063651341952682055100221PM2.5
200536511521227110058101179PM2.5
2004366108232204205893219PM2.5
2003365107231224105793219PM2.5
200236510919834177057133224PM2.5
200136510121535131058110201PM2.5
2000366108229253105997203PM2.5
199936514316536201056129210Ozone
19983652277835223046129213Ozone
19973652398527113044101213NO2
19963662271012990045101200NO2
19953652269126184045119218NO2
199436518812736140049112200NO2
199336517412041273052133210NO2
199236617515427100052101192NO2
199136511717143286062143243NO2
19903651491723563055104212NO2
198936516014047162054119217NO2
1988366185111282319050169251NO2
1987365150148282811055154225NO2
198636518213228203051126219Ozone
198536515813650183052133214NO2
198436613718329134058112214NO2
1983365153130293023054185239NO2
198236518712930172050112205NO2
198136519213226132048112256NO2
198036617214428184052122209NO2

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

Counties in Virginia with a similar median AQI in 2025

All monitored counties in Virginia

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem