EnviroNearby

Dunn County, North Dakota air quality history

Daily Air Quality Index summaries from EPA monitors in Dunn, North Dakota, 1980–2025.

80%
Good days in 2025
39
Median daily AQI, 2025
9
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 Dunn, North Dakota on 365 days. 291 of those days (80%) 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 237 days. Across the years with fuller monitoring, the share of Good days fell: an average of 92% in 1980–1982 versus 78% in 2023–2025.

Years with fewer than 120 monitored days (1989, 1998, 2010) 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%1980: Good 282 of 314 days1980: Moderate 22 of 314 days1980: Unhealthy for Sensitive Groups 9 of 314 days1980: Unhealthy 1 of 314 days19801981: Good 317 of 365 days1981: Moderate 47 of 365 days1981: Unhealthy for Sensitive Groups 1 of 365 days1982: Good 359 of 360 days1982: Moderate 1 of 360 days1983: Good 334 of 356 days1983: Moderate 22 of 356 days1984: Good 348 of 365 days1984: Moderate 17 of 365 days1985: Good 359 of 365 days1985: Moderate 6 of 365 days19851986: Good 358 of 365 days1986: Moderate 7 of 365 days1987: Good 318 of 326 days1987: Moderate 8 of 326 days1988: Good 287 of 313 days1988: Moderate 26 of 313 days1989: Good 71 of 71 days1998: Good 17 of 17 days19981999: Good 357 of 365 days1999: Moderate 8 of 365 days2000: Good 366 of 366 days2001: Good 349 of 364 days2001: Moderate 15 of 364 days2002: Good 356 of 365 days2002: Moderate 9 of 365 days2003: Good 338 of 364 days2003: Moderate 26 of 364 days20032004: Good 365 of 365 days2005: Good 359 of 362 days2005: Moderate 3 of 362 days2006: Good 344 of 365 days2006: Moderate 21 of 365 days2007: Good 358 of 365 days2007: Moderate 7 of 365 days2008: Good 340 of 363 days2008: Moderate 23 of 363 days20082009: Good 349 of 352 days2009: Moderate 3 of 352 days2010: Good 102 of 112 days2010: Moderate 10 of 112 days2011: Good 278 of 290 days2011: Moderate 12 of 290 days2012: Good 300 of 365 days2012: Moderate 65 of 365 days2013: Good 327 of 363 days2013: Moderate 36 of 363 days20132014: Good 332 of 362 days2014: Moderate 29 of 362 days2014: Unhealthy for Sensitive Groups 1 of 362 days2015: Good 295 of 365 days2015: Moderate 59 of 365 days2015: Unhealthy for Sensitive Groups 10 of 365 days2015: Unhealthy 1 of 365 days2016: Good 345 of 366 days2016: Moderate 21 of 366 days2017: Good 288 of 330 days2017: Moderate 40 of 330 days2017: Unhealthy for Sensitive Groups 1 of 330 days2017: Unhealthy 1 of 330 days2018: Good 297 of 349 days2018: Moderate 52 of 349 days20182019: Good 343 of 365 days2019: Moderate 22 of 365 days2020: Good 347 of 366 days2020: Moderate 19 of 366 days2021: Good 277 of 365 days2021: Moderate 78 of 365 days2021: Unhealthy for Sensitive Groups 7 of 365 days2021: Unhealthy 3 of 365 days2022: Good 308 of 362 days2022: Moderate 54 of 362 days2023: Good 263 of 365 days2023: Moderate 85 of 365 days2023: Unhealthy for Sensitive Groups 11 of 365 days2023: Unhealthy 5 of 365 days2023: Hazardous 1 of 365 days20232024: Good 304 of 365 days2024: Moderate 53 of 365 days2024: Unhealthy for Sensitive Groups 5 of 365 days2024: Unhealthy 3 of 365 days2025: Good 291 of 365 days2025: Moderate 65 of 365 days2025: Unhealthy for Sensitive Groups 6 of 365 days2025: Unhealthy 2 of 365 days2025: Very Unhealthy 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 year0501001980: 90th percentile AQI 511981: 90th percentile AQI 581982: 90th percentile AQI 401983: 90th percentile AQI 481984: 90th percentile AQI 461985: 90th percentile AQI 441986: 90th percentile AQI 441987: 90th percentile AQI 451988: 90th percentile AQI 491989: 90th percentile AQI 61998: 90th percentile AQI 331999: 90th percentile AQI 452000: 90th percentile AQI 432001: 90th percentile AQI 472002: 90th percentile AQI 462003: 90th percentile AQI 492004: 90th percentile AQI 412005: 90th percentile AQI 422006: 90th percentile AQI 472007: 90th percentile AQI 442008: 90th percentile AQI 472009: 90th percentile AQI 442010: 90th percentile AQI 492011: 90th percentile AQI 452012: 90th percentile AQI 542013: 90th percentile AQI 502014: 90th percentile AQI 492015: 90th percentile AQI 612016: 90th percentile AQI 472017: 90th percentile AQI 522018: 90th percentile AQI 542019: 90th percentile AQI 472020: 90th percentile AQI 462021: 90th percentile AQI 682022: 90th percentile AQI 532023: 90th percentile AQI 692024: 90th percentile AQI 612025: 90th percentile AQI 611980: Median AQI 301981: Median AQI 341982: Median AQI 261983: Median AQI 351984: Median AQI 351985: Median AQI 341986: Median AQI 321987: Median AQI 251988: Median AQI 311989: Median AQI 01998: Median AQI 311999: Median AQI 352000: Median AQI 302001: Median AQI 352002: Median AQI 342003: Median AQI 352004: Median AQI 312005: Median AQI 312006: Median AQI 322007: Median AQI 312008: Median AQI 342009: Median AQI 332010: Median AQI 412011: Median AQI 332012: Median AQI 392013: Median AQI 352014: Median AQI 352015: Median AQI 382016: Median AQI 352017: Median AQI 372018: Median AQI 352019: Median AQI 352020: Median AQI 342021: Median AQI 392022: Median AQI 372023: Median AQI 412024: Median AQI 372025: Median AQI 39198019851998200320082013201820232025
  • 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
Ozone23765%
Fine particles (PM2.5)12835%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253652916562103961217Ozone
20243653045353003761157Ozone
202336526385115014169318Ozone
2022362308540000375382Ozone
20213652777873003968184Ozone
2020366347190000344662Ozone
2019365343220000354787Ozone
2018349297520000355490Ozone
20173302884011003752157Ozone
2016366345210000354790Ozone
201536529559101003861153Ozone
20143623322910003549103Ozone
2013363327360000355067Ozone
2012365300650000395475Ozone
2011290278120000334571Ozone
2010112102100000414987Ozone
200935234930000334458Ozone
2008363340230000344777Ozone
200736535870000314464Ozone
2006365344210000324787Ozone
200536235930000314264Ozone
200436536500000314150Ozone
2003364338260000354997Ozone
200236535690000344674Ozone
2001364349150000354774Ozone
200036636600000304350Ozone
199936535780000354567Ozone
1998171700000313335Ozone
19897171000000613NO2
19883132872600003149100Ozone
198732631880000254564Ozone
198636535870000324487Ozone
198536535960000344467Ozone
1984365348170000354684Ozone
1983356334220000354880Ozone
198236035910000264058Ozone
19813653174710003458115Ozone
19803142822291003051161Ozone

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 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