EnviroNearby

McKenzie County, North Dakota air quality history

Daily Air Quality Index summaries from EPA monitors in McKenzie, North Dakota, 1982–2025.

81%
Good days in 2025
39
Median daily AQI, 2025
6
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 McKenzie, North Dakota on 365 days. 295 of those days (81%) were in the Good range, and the median daily AQI was 39. That median is about the same as the typical monitored county in North Dakota (median 38 across 9 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 267 days. Across the years with fuller monitoring, the share of Good days fell: an average of 97% in 1983–1985 versus 80% in 2023–2025.

Years with fewer than 120 monitored days (1982, 1998, 1999, 2000) are shown in the table but left out of comparisons and trend statements.

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%1982: Good 55 of 55 days19821983: Good 222 of 234 days1983: Moderate 11 of 234 days1983: Unhealthy for Sensitive Groups 1 of 234 days1984: Good 345 of 358 days1984: Moderate 13 of 358 days1985: Good 323 of 325 days1985: Moderate 2 of 325 days1986: Good 264 of 268 days1986: Moderate 4 of 268 days1987: Good 176 of 179 days1987: Moderate 3 of 179 days19871988: Good 95 of 135 days1988: Moderate 39 of 135 days1988: Unhealthy for Sensitive Groups 1 of 135 days1989: Good 138 of 176 days1989: Moderate 37 of 176 days1989: Unhealthy for Sensitive Groups 1 of 176 days1990: Good 109 of 121 days1990: Moderate 12 of 121 days1991: Good 132 of 148 days1991: Moderate 16 of 148 days1992: Good 183 of 190 days1992: Moderate 7 of 190 days19921993: Good 186 of 191 days1993: Moderate 5 of 191 days1994: Good 186 of 198 days1994: Moderate 12 of 198 days1995: Good 169 of 179 days1995: Moderate 10 of 179 days1996: Good 136 of 153 days1996: Moderate 17 of 153 days1997: Good 166 of 198 days1997: Moderate 28 of 198 days1997: Unhealthy for Sensitive Groups 4 of 198 days19971998: Good 72 of 83 days1998: Moderate 11 of 83 days1999: Good 59 of 59 days2000: Good 61 of 61 days2001: Good 183 of 189 days2001: Moderate 6 of 189 days2002: Good 337 of 365 days2002: Moderate 28 of 365 days20022003: Good 316 of 365 days2003: Moderate 45 of 365 days2003: Unhealthy for Sensitive Groups 4 of 365 days2004: Good 351 of 366 days2004: Moderate 15 of 366 days2005: Good 346 of 365 days2005: Moderate 19 of 365 days2006: Good 307 of 364 days2006: Moderate 57 of 364 days2007: Good 337 of 365 days2007: Moderate 27 of 365 days2007: Unhealthy for Sensitive Groups 1 of 365 days20072008: Good 341 of 366 days2008: Moderate 25 of 366 days2009: Good 352 of 361 days2009: Moderate 9 of 361 days2010: Good 299 of 364 days2010: Moderate 65 of 364 days2011: Good 198 of 354 days2011: Moderate 155 of 354 days2011: Very Unhealthy 1 of 354 days2012: Good 252 of 364 days2012: Moderate 112 of 364 days20122013: Good 326 of 365 days2013: Moderate 39 of 365 days2014: Good 323 of 352 days2014: Moderate 27 of 352 days2014: Unhealthy for Sensitive Groups 1 of 352 days2014: Very Unhealthy 1 of 352 days2015: Good 315 of 364 days2015: Moderate 43 of 364 days2015: Unhealthy for Sensitive Groups 4 of 364 days2015: Unhealthy 2 of 364 days2016: Good 356 of 366 days2016: Moderate 10 of 366 days2017: Good 307 of 356 days2017: Moderate 47 of 356 days2017: Unhealthy for Sensitive Groups 1 of 356 days2017: Unhealthy 1 of 356 days20172018: Good 293 of 355 days2018: Moderate 62 of 355 days2019: Good 343 of 365 days2019: Moderate 22 of 365 days2020: Good 346 of 363 days2020: Moderate 17 of 363 days2021: Good 286 of 356 days2021: Moderate 62 of 356 days2021: Unhealthy for Sensitive Groups 6 of 356 days2021: Unhealthy 2 of 356 days2022: Good 294 of 331 days2022: Moderate 37 of 331 days20222023: Good 277 of 364 days2023: Moderate 72 of 364 days2023: Unhealthy for Sensitive Groups 10 of 364 days2023: Unhealthy 4 of 364 days2023: Very Unhealthy 1 of 364 days2024: Good 300 of 366 days2024: Moderate 58 of 366 days2024: Unhealthy for Sensitive Groups 6 of 366 days2024: Unhealthy 2 of 366 days2025: Good 295 of 365 days2025: Moderate 64 of 365 days2025: Unhealthy for Sensitive Groups 4 of 365 days2025: Unhealthy 2 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 year0501001982: 90th percentile AQI 261983: 90th percentile AQI 441984: 90th percentile AQI 441985: 90th percentile AQI 441986: 90th percentile AQI 441987: 90th percentile AQI 461988: 90th percentile AQI 671989: 90th percentile AQI 641990: 90th percentile AQI 501991: 90th percentile AQI 541992: 90th percentile AQI 471993: 90th percentile AQI 441994: 90th percentile AQI 491995: 90th percentile AQI 501996: 90th percentile AQI 511997: 90th percentile AQI 641998: 90th percentile AQI 541999: 90th percentile AQI 112000: 90th percentile AQI 92001: 90th percentile AQI 432002: 90th percentile AQI 492003: 90th percentile AQI 582004: 90th percentile AQI 472005: 90th percentile AQI 462006: 90th percentile AQI 582007: 90th percentile AQI 482008: 90th percentile AQI 492009: 90th percentile AQI 462010: 90th percentile AQI 552011: 90th percentile AQI 582012: 90th percentile AQI 582013: 90th percentile AQI 512014: 90th percentile AQI 492015: 90th percentile AQI 542016: 90th percentile AQI 452017: 90th percentile AQI 532018: 90th percentile AQI 572019: 90th percentile AQI 492020: 90th percentile AQI 442021: 90th percentile AQI 722022: 90th percentile AQI 512023: 90th percentile AQI 642024: 90th percentile AQI 612025: 90th percentile AQI 611982: Median AQI 211983: Median AQI 291984: Median AQI 311985: Median AQI 331986: Median AQI 351987: Median AQI 361988: Median AQI 451989: Median AQI 441990: Median AQI 401991: Median AQI 401992: Median AQI 381993: Median AQI 351994: Median AQI 411995: Median AQI 401996: Median AQI 431997: Median AQI 421998: Median AQI 321999: Median AQI 52000: Median AQI 62001: Median AQI 282002: Median AQI 362003: Median AQI 362004: Median AQI 352005: Median AQI 352006: Median AQI 372007: Median AQI 352008: Median AQI 362009: Median AQI 352010: Median AQI 412011: Median AQI 482012: Median AQI 422013: Median AQI 382014: Median AQI 362015: Median AQI 352016: Median AQI 332017: Median AQI 372018: Median AQI 382019: Median AQI 352020: Median AQI 342021: Median AQI 362022: Median AQI 352023: Median AQI 392024: Median AQI 392025: Median AQI 391982198719921997200220072012201720222025
  • 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
Ozone26773%
Fine particles (PM2.5)9827%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253652956442003961197Ozone
20243663005862003961172Ozone
202336427772104103964298Ozone
2022331294370000355175Ozone
20213562866262003672183Ozone
2020363346170000344466Ozone
2019365343220000354977Ozone
2018355293620000385793Ozone
20173563074711003753155Ozone
2016366356100000334589Ozone
20153643154342003554161Ozone
20143523232710103649205Ozone
2013365326390000385174Ozone
20123642521120000425887PM2.5
201135419815500104858262PM2.5
20103642996500004155100Ozone
200936135290000354661Ozone
2008366341250000364977Ozone
20073653372710003548101Ozone
2006364307570000375897Ozone
2005365346190000354679Ozone
2004366351150000354780Ozone
20033653164540003658133Ozone
2002365337280000364977Ozone
200118918360000284384Ozone
20006161000006916PM10
199959590000051116PM10
19988372110000325484Ozone
19971981662840004264133Ozone
1996153136170000435167Ozone
1995179169100000405064Ozone
1994198186120000414984Ozone
199319118650000354474Ozone
199219018370000384767Ozone
1991148132160000405474Ozone
1990121109120000405084Ozone
19891761383710004464105Ozone
1988135953910004567112Ozone
198717917630000364654Ozone
198626826440000354461Ozone
198532532320000334461Ozone
1984358345130000314477Ozone
19832342221110002944122Ozone
1982555500000212627Ozone

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 North Dakota with a similar median AQI in 2025

All monitored counties in North Dakota

Source: U.S. EPA AirData, “Annual AQI by County” files for 1982–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem