EnviroNearby

Saint Louis County, Minnesota air quality history

Daily Air Quality Index summaries from EPA monitors in Saint Louis, Minnesota, 1980–2025.

67%
Good days in 2025
42
Median daily AQI, 2025
23
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 Saint Louis, Minnesota on 365 days. 243 of those days (67%) were in the Good range, and the median daily AQI was 42. That median is higher than the typical monitored county in Minnesota (median 37 across 21 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 185 days. Across the years with fuller monitoring, the share of Good days rose: an average of 61% in 1980–1982 versus 68% 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 221 of 364 days1980: Moderate 135 of 364 days1980: Unhealthy for Sensitive Groups 7 of 364 days1980: Unhealthy 1 of 364 days19801981: Good 206 of 354 days1981: Moderate 141 of 354 days1981: Unhealthy for Sensitive Groups 7 of 354 days1982: Good 228 of 352 days1982: Moderate 121 of 352 days1982: Unhealthy for Sensitive Groups 3 of 352 days1983: Good 265 of 336 days1983: Moderate 71 of 336 days1984: Good 243 of 335 days1984: Moderate 88 of 335 days1984: Unhealthy for Sensitive Groups 1 of 335 days1984: Unhealthy 3 of 335 days1985: Good 289 of 357 days1985: Moderate 65 of 357 days1985: Unhealthy for Sensitive Groups 2 of 357 days1985: Hazardous 1 of 357 days19851986: Good 259 of 364 days1986: Moderate 103 of 364 days1986: Unhealthy for Sensitive Groups 2 of 364 days1987: Good 257 of 364 days1987: Moderate 105 of 364 days1987: Unhealthy for Sensitive Groups 1 of 364 days1987: Unhealthy 1 of 364 days1988: Good 315 of 352 days1988: Moderate 37 of 352 days1989: Good 293 of 365 days1989: Moderate 69 of 365 days1989: Unhealthy for Sensitive Groups 3 of 365 days1990: Good 353 of 364 days1990: Moderate 11 of 364 days19901991: Good 350 of 365 days1991: Moderate 15 of 365 days1992: Good 344 of 363 days1992: Moderate 19 of 363 days1993: Good 353 of 362 days1993: Moderate 9 of 362 days1994: Good 348 of 349 days1994: Moderate 1 of 349 days1995: Good 362 of 365 days1995: Moderate 3 of 365 days19951996: Good 356 of 366 days1996: Moderate 10 of 366 days1997: Good 340 of 365 days1997: Moderate 20 of 365 days1997: Unhealthy for Sensitive Groups 5 of 365 days1998: Good 342 of 365 days1998: Moderate 21 of 365 days1998: Unhealthy for Sensitive Groups 2 of 365 days1999: Good 324 of 365 days1999: Moderate 37 of 365 days1999: Unhealthy for Sensitive Groups 4 of 365 days2000: Good 290 of 366 days2000: Moderate 74 of 366 days2000: Unhealthy for Sensitive Groups 2 of 366 days20002001: Good 308 of 365 days2001: Moderate 57 of 365 days2002: Good 320 of 365 days2002: Moderate 45 of 365 days2003: Good 217 of 365 days2003: Moderate 146 of 365 days2003: Unhealthy for Sensitive Groups 2 of 365 days2004: Good 240 of 366 days2004: Moderate 124 of 366 days2004: Unhealthy for Sensitive Groups 2 of 366 days2005: Good 220 of 365 days2005: Moderate 140 of 365 days2005: Unhealthy for Sensitive Groups 5 of 365 days20052006: Good 182 of 365 days2006: Moderate 183 of 365 days2007: Good 186 of 365 days2007: Moderate 177 of 365 days2007: Unhealthy for Sensitive Groups 2 of 365 days2008: Good 208 of 366 days2008: Moderate 157 of 366 days2008: Unhealthy for Sensitive Groups 1 of 366 days2009: Good 218 of 365 days2009: Moderate 147 of 365 days2010: Good 260 of 365 days2010: Moderate 104 of 365 days2010: Unhealthy for Sensitive Groups 1 of 365 days20102011: Good 268 of 365 days2011: Moderate 96 of 365 days2011: Unhealthy for Sensitive Groups 1 of 365 days2012: Good 280 of 366 days2012: Moderate 85 of 366 days2012: Unhealthy for Sensitive Groups 1 of 366 days2013: Good 238 of 365 days2013: Moderate 127 of 365 days2014: Good 216 of 365 days2014: Moderate 149 of 365 days2015: Good 289 of 365 days2015: Moderate 75 of 365 days2015: Unhealthy for Sensitive Groups 1 of 365 days20152016: Good 323 of 366 days2016: Moderate 42 of 366 days2016: Unhealthy for Sensitive Groups 1 of 366 days2017: Good 307 of 365 days2017: Moderate 58 of 365 days2018: Good 284 of 365 days2018: Moderate 79 of 365 days2018: Unhealthy for Sensitive Groups 2 of 365 days2019: Good 306 of 365 days2019: Moderate 58 of 365 days2019: Unhealthy for Sensitive Groups 1 of 365 days2020: Good 279 of 366 days2020: Moderate 86 of 366 days2020: Unhealthy for Sensitive Groups 1 of 366 days20202021: Good 283 of 365 days2021: Moderate 72 of 365 days2021: Unhealthy for Sensitive Groups 8 of 365 days2021: Unhealthy 2 of 365 days2022: Good 322 of 365 days2022: Moderate 43 of 365 days2023: Good 221 of 365 days2023: Moderate 136 of 365 days2023: Unhealthy for Sensitive Groups 6 of 365 days2023: Unhealthy 1 of 365 days2023: Very Unhealthy 1 of 365 days2024: Good 286 of 366 days2024: Moderate 77 of 366 days2024: Unhealthy for Sensitive Groups 3 of 366 days2025: Good 243 of 365 days2025: Moderate 99 of 365 days2025: Unhealthy for Sensitive Groups 11 of 365 days2025: Unhealthy 11 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 751981: 90th percentile AQI 781982: 90th percentile AQI 701983: 90th percentile AQI 591984: 90th percentile AQI 651985: 90th percentile AQI 591986: 90th percentile AQI 621987: 90th percentile AQI 601988: 90th percentile AQI 511989: 90th percentile AQI 601990: 90th percentile AQI 391991: 90th percentile AQI 381992: 90th percentile AQI 391993: 90th percentile AQI 361994: 90th percentile AQI 311995: 90th percentile AQI 311996: 90th percentile AQI 421997: 90th percentile AQI 481998: 90th percentile AQI 481999: 90th percentile AQI 512000: 90th percentile AQI 602001: 90th percentile AQI 562002: 90th percentile AQI 542003: 90th percentile AQI 712004: 90th percentile AQI 642005: 90th percentile AQI 722006: 90th percentile AQI 672007: 90th percentile AQI 702008: 90th percentile AQI 652009: 90th percentile AQI 682010: 90th percentile AQI 642011: 90th percentile AQI 612012: 90th percentile AQI 592013: 90th percentile AQI 602014: 90th percentile AQI 612015: 90th percentile AQI 562016: 90th percentile AQI 522017: 90th percentile AQI 552018: 90th percentile AQI 612019: 90th percentile AQI 552020: 90th percentile AQI 552021: 90th percentile AQI 642022: 90th percentile AQI 522023: 90th percentile AQI 742024: 90th percentile AQI 572025: 90th percentile AQI 791980: Median AQI 451981: Median AQI 451982: Median AQI 421983: Median AQI 361984: Median AQI 401985: Median AQI 331986: Median AQI 391987: Median AQI 431988: Median AQI 331989: Median AQI 401990: Median AQI 241991: Median AQI 221992: Median AQI 201993: Median AQI 191994: Median AQI 191995: Median AQI 171996: Median AQI 261997: Median AQI 351998: Median AQI 341999: Median AQI 342000: Median AQI 372001: Median AQI 322002: Median AQI 342003: Median AQI 442004: Median AQI 442005: Median AQI 452006: Median AQI 512007: Median AQI 502008: Median AQI 472009: Median AQI 472010: Median AQI 412011: Median AQI 412012: Median AQI 382013: Median AQI 442014: Median AQI 472015: Median AQI 402016: Median AQI 342017: Median AQI 362018: Median AQI 392019: Median AQI 382020: Median AQI 402021: Median AQI 372022: Median AQI 362023: Median AQI 442024: Median AQI 392025: 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
Fine particles (PM2.5)18551%
Ozone18049%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025365243991111104279216PM2.5
20243662867730003957114Ozone
202336522113661104474286PM2.5
2022365322430000365275Ozone
20213652837282003764159Ozone
20203662798610004055104PM2.5
20193653065810003855101PM2.5
20183652847920003961109Ozone
2017365307580000365586Ozone
20163663234210003452128Ozone
20153652897510004056104PM2.5
20143652161490000476184PM2.5
20133652381270000446084PM2.5
20123662808510003859112Ozone
20113652689610004161101Ozone
201036526010410004164101Ozone
20093652181470000476891PM2.5
200836620815710004765139PM2.5
200736518617720005070115PM2.5
20063651821830000516797PM2.5
200536522014050004572133PM2.5
200436624012420004464118PM2.5
200336521714620004471142PM2.5
2002365320450000345498Ozone
20013653085700003256100Ozone
20003662907420003760119Ozone
19993653243740003451122Ozone
19983653422120003448119Ozone
19973653402050003548133Ozone
1996366356100000264293CO
199536536230000173170CO
199434934810000193154CO
199336235390000193674CO
1992363344190000203976CO
1991365350150000223876CO
1990364353110000243977CO
19893652936930004060126CO
1988352315370000335175CO
198736425710511004360156CO
198636425910320003962131CO
19853572896520013359419CO
19843352438813004065178CO
1983336265710000365997CO
198235222812130004270111CO
198135420614170004578150CO
198036422113571004575181CO

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 Minnesota with a similar median AQI in 2025

All monitored counties in Minnesota

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