EnviroNearby

St. Joseph County, Indiana air quality history

Daily Air Quality Index summaries from EPA monitors in St. Joseph, Indiana, 1980–2025.

66%
Good days in 2025
43
Median daily AQI, 2025
7
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 St. Joseph, Indiana on 365 days. 241 of those days (66%) were in the Good range, and the median daily AQI was 43. That median is about the same as the typical monitored county in Indiana (median 41 across 33 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 204 days. Across the years with fuller monitoring, the share of Good days fell: an average of 75% in 1980–1982 versus 60% 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 290 of 363 days1980: Moderate 31 of 363 days1980: Unhealthy for Sensitive Groups 25 of 363 days1980: Unhealthy 11 of 363 days1980: Very Unhealthy 6 of 363 days19801981: Good 278 of 358 days1981: Moderate 46 of 358 days1981: Unhealthy for Sensitive Groups 24 of 358 days1981: Unhealthy 10 of 358 days1982: Good 242 of 365 days1982: Moderate 79 of 365 days1982: Unhealthy for Sensitive Groups 28 of 365 days1982: Unhealthy 16 of 365 days1983: Good 251 of 365 days1983: Moderate 49 of 365 days1983: Unhealthy for Sensitive Groups 41 of 365 days1983: Unhealthy 21 of 365 days1983: Very Unhealthy 3 of 365 days1984: Good 279 of 366 days1984: Moderate 52 of 366 days1984: Unhealthy for Sensitive Groups 30 of 366 days1984: Unhealthy 5 of 366 days1985: Good 257 of 362 days1985: Moderate 66 of 362 days1985: Unhealthy for Sensitive Groups 31 of 362 days1985: Unhealthy 8 of 362 days19851986: Good 300 of 363 days1986: Moderate 51 of 363 days1986: Unhealthy for Sensitive Groups 12 of 363 days1987: Good 287 of 363 days1987: Moderate 46 of 363 days1987: Unhealthy for Sensitive Groups 24 of 363 days1987: Unhealthy 6 of 363 days1988: Good 269 of 366 days1988: Moderate 51 of 366 days1988: Unhealthy for Sensitive Groups 22 of 366 days1988: Unhealthy 21 of 366 days1988: Very Unhealthy 3 of 366 days1989: Good 293 of 364 days1989: Moderate 57 of 364 days1989: Unhealthy for Sensitive Groups 12 of 364 days1989: Unhealthy 2 of 364 days1990: Good 281 of 362 days1990: Moderate 59 of 362 days1990: Unhealthy for Sensitive Groups 19 of 362 days1990: Unhealthy 3 of 362 days19901991: Good 258 of 362 days1991: Moderate 49 of 362 days1991: Unhealthy for Sensitive Groups 47 of 362 days1991: Unhealthy 8 of 362 days1992: Good 230 of 297 days1992: Moderate 51 of 297 days1992: Unhealthy for Sensitive Groups 12 of 297 days1992: Unhealthy 4 of 297 days1993: Good 222 of 295 days1993: Moderate 53 of 295 days1993: Unhealthy for Sensitive Groups 19 of 295 days1993: Unhealthy 1 of 295 days1994: Good 275 of 365 days1994: Moderate 62 of 365 days1994: Unhealthy for Sensitive Groups 21 of 365 days1994: Unhealthy 6 of 365 days1994: Very Unhealthy 1 of 365 days1995: Good 270 of 365 days1995: Moderate 58 of 365 days1995: Unhealthy for Sensitive Groups 24 of 365 days1995: Unhealthy 12 of 365 days1995: Very Unhealthy 1 of 365 days19951996: Good 283 of 366 days1996: Moderate 53 of 366 days1996: Unhealthy for Sensitive Groups 21 of 366 days1996: Unhealthy 9 of 366 days1997: Good 296 of 364 days1997: Moderate 45 of 364 days1997: Unhealthy for Sensitive Groups 16 of 364 days1997: Unhealthy 6 of 364 days1997: Very Unhealthy 1 of 364 days1998: Good 258 of 359 days1998: Moderate 71 of 359 days1998: Unhealthy for Sensitive Groups 21 of 359 days1998: Unhealthy 9 of 359 days1999: Good 165 of 281 days1999: Moderate 78 of 281 days1999: Unhealthy for Sensitive Groups 29 of 281 days1999: Unhealthy 9 of 281 days2000: Good 225 of 365 days2000: Moderate 127 of 365 days2000: Unhealthy for Sensitive Groups 10 of 365 days2000: Unhealthy 3 of 365 days20002001: Good 225 of 365 days2001: Moderate 114 of 365 days2001: Unhealthy for Sensitive Groups 21 of 365 days2001: Unhealthy 5 of 365 days2002: Good 118 of 365 days2002: Moderate 202 of 365 days2002: Unhealthy for Sensitive Groups 23 of 365 days2002: Unhealthy 19 of 365 days2002: Very Unhealthy 3 of 365 days2003: Good 126 of 365 days2003: Moderate 210 of 365 days2003: Unhealthy for Sensitive Groups 24 of 365 days2003: Unhealthy 5 of 365 days2004: Good 243 of 366 days2004: Moderate 113 of 366 days2004: Unhealthy for Sensitive Groups 9 of 366 days2004: Unhealthy 1 of 366 days2005: Good 172 of 333 days2005: Moderate 125 of 333 days2005: Unhealthy for Sensitive Groups 31 of 333 days2005: Unhealthy 5 of 333 days20052006: Good 248 of 365 days2006: Moderate 111 of 365 days2006: Unhealthy for Sensitive Groups 6 of 365 days2007: Good 119 of 365 days2007: Moderate 229 of 365 days2007: Unhealthy for Sensitive Groups 17 of 365 days2008: Good 227 of 366 days2008: Moderate 137 of 366 days2008: Unhealthy for Sensitive Groups 2 of 366 days2009: Good 151 of 365 days2009: Moderate 210 of 365 days2009: Unhealthy for Sensitive Groups 4 of 365 days2010: Good 101 of 355 days2010: Moderate 244 of 355 days2010: Unhealthy for Sensitive Groups 10 of 355 days20102011: Good 128 of 363 days2011: Moderate 227 of 363 days2011: Unhealthy for Sensitive Groups 7 of 363 days2011: Unhealthy 1 of 363 days2012: Good 113 of 366 days2012: Moderate 234 of 366 days2012: Unhealthy for Sensitive Groups 17 of 366 days2012: Unhealthy 1 of 366 days2012: Very Unhealthy 1 of 366 days2013: Good 112 of 361 days2013: Moderate 246 of 361 days2013: Unhealthy for Sensitive Groups 2 of 361 days2013: Unhealthy 1 of 361 days2014: Good 159 of 365 days2014: Moderate 202 of 365 days2014: Unhealthy for Sensitive Groups 4 of 365 days2015: Good 152 of 362 days2015: Moderate 208 of 362 days2015: Unhealthy for Sensitive Groups 2 of 362 days20152016: Good 182 of 364 days2016: Moderate 174 of 364 days2016: Unhealthy for Sensitive Groups 8 of 364 days2017: Good 236 of 365 days2017: Moderate 125 of 365 days2017: Unhealthy for Sensitive Groups 4 of 365 days2018: Good 173 of 365 days2018: Moderate 185 of 365 days2018: Unhealthy for Sensitive Groups 7 of 365 days2019: Good 217 of 365 days2019: Moderate 148 of 365 days2020: Good 207 of 366 days2020: Moderate 154 of 366 days2020: Unhealthy for Sensitive Groups 4 of 366 days2020: Unhealthy 1 of 366 days20202021: Good 169 of 365 days2021: Moderate 195 of 365 days2021: Unhealthy for Sensitive Groups 1 of 365 days2022: Good 167 of 365 days2022: Moderate 192 of 365 days2022: Unhealthy for Sensitive Groups 6 of 365 days2023: Good 175 of 365 days2023: Moderate 177 of 365 days2023: Unhealthy for Sensitive Groups 10 of 365 days2023: Unhealthy 2 of 365 days2023: Very Unhealthy 1 of 365 days2024: Good 237 of 366 days2024: Moderate 127 of 366 days2024: Unhealthy for Sensitive Groups 2 of 366 days2025: Good 241 of 365 days2025: Moderate 117 of 365 days2025: Unhealthy for Sensitive Groups 7 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 year0501001501980: 90th percentile AQI 1121981: 90th percentile AQI 1001982: 90th percentile AQI 1081983: 90th percentile AQI 1331984: 90th percentile AQI 1001985: 90th percentile AQI 1011986: 90th percentile AQI 611987: 90th percentile AQI 901988: 90th percentile AQI 1331989: 90th percentile AQI 771990: 90th percentile AQI 841991: 90th percentile AQI 1151992: 90th percentile AQI 801993: 90th percentile AQI 841994: 90th percentile AQI 931995: 90th percentile AQI 1011996: 90th percentile AQI 901997: 90th percentile AQI 871998: 90th percentile AQI 971999: 90th percentile AQI 1122000: 90th percentile AQI 772001: 90th percentile AQI 922002: 90th percentile AQI 1082003: 90th percentile AQI 952004: 90th percentile AQI 772005: 90th percentile AQI 1012006: 90th percentile AQI 722007: 90th percentile AQI 882008: 90th percentile AQI 752009: 90th percentile AQI 762010: 90th percentile AQI 822011: 90th percentile AQI 772012: 90th percentile AQI 902013: 90th percentile AQI 742014: 90th percentile AQI 742015: 90th percentile AQI 712016: 90th percentile AQI 692017: 90th percentile AQI 642018: 90th percentile AQI 672019: 90th percentile AQI 662020: 90th percentile AQI 652021: 90th percentile AQI 712022: 90th percentile AQI 732023: 90th percentile AQI 732024: 90th percentile AQI 642025: 90th percentile AQI 711980: Median AQI 271981: Median AQI 331982: Median AQI 431983: Median AQI 391984: Median AQI 351985: Median AQI 381986: Median AQI 331987: Median AQI 331988: Median AQI 341989: Median AQI 311990: Median AQI 321991: Median AQI 321992: Median AQI 361993: Median AQI 371994: Median AQI 341995: Median AQI 361996: Median AQI 341997: Median AQI 341998: Median AQI 361999: Median AQI 452000: Median AQI 422001: Median AQI 432002: Median AQI 562003: Median AQI 562004: Median AQI 422005: Median AQI 492006: Median AQI 402007: Median AQI 562008: Median AQI 442009: Median AQI 542010: Median AQI 582011: Median AQI 562012: Median AQI 572013: Median AQI 572014: Median AQI 532015: Median AQI 532016: Median AQI 512017: Median AQI 442018: Median AQI 512019: Median AQI 462020: Median AQI 472021: Median AQI 522022: Median AQI 522023: Median AQI 512024: Median AQI 452025: Median AQI 431980198519901995200020052010201520202025
  • 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
Ozone20456%
Fine particles (PM2.5)16144%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536524111770004371127Ozone
202436623712720004564119Ozone
2023365175177102105173223PM2.5
202236516719260005273122PM2.5
202136516919510005271105PM2.5
202036620715441004765166PM2.5
201936521714800004666100PM2.5
201836517318570005167133PM2.5
201736523612540004464133PM2.5
201636418217480005169119PM2.5
201536215220820005371134PM2.5
201436515920240005374129PM2.5
201336111224621005774155PM2.5
2012366113234171105790213PM2.5
201136312822771005677161PM2.5
2010355101244100005882128PM2.5
200936515121040005476107PM2.5
200836622713720004475108Ozone
2007365119229170005688150PM2.5
200636524811160004072115Ozone
20053331721253150049101177Ozone
200436624311391004277164Ozone
2003365126210245005695179PM2.5
200236511820223193056108216PM2.5
2001365225114215004392172Ozone
2000365225127103004277166Ozone
1999281165782990045112174Ozone
199835925871219003697195NO2
199736429645166103487203NO2
199636628353219003490185Ozone
19953652705824121036101201Ozone
199436527562216103493202Ozone
199329522253191003784166Ozone
199229723051124003680179Ozone
1991362258494780032115185Ozone
199036228159193003284159Ozone
198936429357122003177166Ozone
19883662695122213034133212Ozone
198736328746246003390200Ozone
198636330051120003361150Ozone
1985362257663180038101190Ozone
1984366279523050035100169Ozone
19833652514941213039133216Ozone
19823652427928160043108185Ozone
19813582784624100033100197Ozone
19803632903125116027112220Ozone

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 Indiana with a similar median AQI in 2025

All monitored counties in Indiana

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