EnviroNearby

Cass County, Nebraska air quality history

Daily Air Quality Index summaries from EPA monitors in Cass, Nebraska, 1985–2025.

96%
Good days in 2025
19
Median daily AQI, 2025
0
Days above 100 in 2025
339
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Cass, Nebraska on 339 days. 325 of those days (96%) were in the Good range, and the median daily AQI was 19. That median is lower than the typical monitored county in Nebraska (median 34 across 10 counties), and lower than the typical monitored U.S. county (40). The main pollutant was coarse particles (PM10) on 339 days. Across the years with fuller monitoring, the share of Good days rose: an average of 79% in 1985–1987 versus 96% in 2023–2025.

Years with fewer than 120 monitored days (1998, 1999) 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%1985: Good 212 of 286 days1985: Moderate 72 of 286 days1985: Unhealthy for Sensitive Groups 2 of 286 days19851986: Good 279 of 331 days1986: Moderate 52 of 331 days1987: Good 253 of 316 days1987: Moderate 63 of 316 days1988: Good 129 of 172 days1988: Moderate 43 of 172 days1989: Good 141 of 176 days1989: Moderate 35 of 176 days1990: Good 143 of 169 days1990: Moderate 26 of 169 days19901991: Good 139 of 166 days1991: Moderate 27 of 166 days1992: Good 163 of 179 days1992: Moderate 16 of 179 days1993: Good 159 of 170 days1993: Moderate 10 of 170 days1993: Unhealthy for Sensitive Groups 1 of 170 days1994: Good 200 of 231 days1994: Moderate 30 of 231 days1994: Unhealthy for Sensitive Groups 1 of 231 days1995: Good 315 of 336 days1995: Moderate 21 of 336 days19951996: Good 301 of 323 days1996: Moderate 22 of 323 days1997: Good 224 of 244 days1997: Moderate 20 of 244 days1998: Good 53 of 63 days1998: Moderate 9 of 63 days1998: Unhealthy for Sensitive Groups 1 of 63 days1999: Good 48 of 105 days1999: Moderate 56 of 105 days1999: Unhealthy for Sensitive Groups 1 of 105 days2000: Good 100 of 164 days2000: Moderate 63 of 164 days2000: Unhealthy for Sensitive Groups 1 of 164 days20002001: Good 294 of 358 days2001: Moderate 64 of 358 days2002: Good 277 of 351 days2002: Moderate 74 of 351 days2003: Good 278 of 352 days2003: Moderate 73 of 352 days2003: Unhealthy for Sensitive Groups 1 of 352 days2004: Good 305 of 365 days2004: Moderate 60 of 365 days2005: Good 267 of 364 days2005: Moderate 96 of 364 days2005: Unhealthy for Sensitive Groups 1 of 364 days20052006: Good 302 of 364 days2006: Moderate 62 of 364 days2007: Good 316 of 357 days2007: Moderate 39 of 357 days2007: Unhealthy for Sensitive Groups 2 of 357 days2008: Good 324 of 360 days2008: Moderate 36 of 360 days2009: Good 344 of 360 days2009: Moderate 16 of 360 days2010: Good 285 of 308 days2010: Moderate 19 of 308 days2010: Unhealthy for Sensitive Groups 3 of 308 days2010: Unhealthy 1 of 308 days20102011: Good 257 of 285 days2011: Moderate 28 of 285 days2012: Good 293 of 346 days2012: Moderate 52 of 346 days2012: Unhealthy for Sensitive Groups 1 of 346 days2013: Good 334 of 355 days2013: Moderate 21 of 355 days2014: Good 316 of 357 days2014: Moderate 41 of 357 days2015: Good 309 of 353 days2015: Moderate 43 of 353 days2015: Unhealthy for Sensitive Groups 1 of 353 days20152016: Good 322 of 352 days2016: Moderate 30 of 352 days2017: Good 335 of 365 days2017: Moderate 30 of 365 days2018: Good 332 of 337 days2018: Moderate 5 of 337 days2019: Good 348 of 348 days2020: Good 346 of 358 days2020: Moderate 12 of 358 days20202021: Good 345 of 351 days2021: Moderate 6 of 351 days2022: Good 337 of 356 days2022: Moderate 19 of 356 days2023: Good 344 of 354 days2023: Moderate 10 of 354 days2024: Good 259 of 274 days2024: Moderate 15 of 274 days2025: Good 325 of 339 days2025: Moderate 14 of 339 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 year0501001985: 90th percentile AQI 611986: 90th percentile AQI 541987: 90th percentile AQI 581988: 90th percentile AQI 601989: 90th percentile AQI 551990: 90th percentile AQI 571991: 90th percentile AQI 561992: 90th percentile AQI 491993: 90th percentile AQI 481994: 90th percentile AQI 531995: 90th percentile AQI 461996: 90th percentile AQI 461997: 90th percentile AQI 491998: 90th percentile AQI 611999: 90th percentile AQI 742000: 90th percentile AQI 642001: 90th percentile AQI 572002: 90th percentile AQI 632003: 90th percentile AQI 592004: 90th percentile AQI 552005: 90th percentile AQI 632006: 90th percentile AQI 572007: 90th percentile AQI 532008: 90th percentile AQI 512009: 90th percentile AQI 412010: 90th percentile AQI 452011: 90th percentile AQI 502012: 90th percentile AQI 562013: 90th percentile AQI 462014: 90th percentile AQI 512015: 90th percentile AQI 542016: 90th percentile AQI 482017: 90th percentile AQI 492018: 90th percentile AQI 312019: 90th percentile AQI 262020: 90th percentile AQI 322021: 90th percentile AQI 372022: 90th percentile AQI 402023: 90th percentile AQI 352024: 90th percentile AQI 382025: 90th percentile AQI 361985: Median AQI 371986: Median AQI 311987: Median AQI 311988: Median AQI 381989: Median AQI 351990: Median AQI 271991: Median AQI 311992: Median AQI 271993: Median AQI 231994: Median AQI 261995: Median AQI 211996: Median AQI 261997: Median AQI 241998: Median AQI 311999: Median AQI 532000: Median AQI 402001: Median AQI 292002: Median AQI 312003: Median AQI 262004: Median AQI 292005: Median AQI 352006: Median AQI 282007: Median AQI 272008: Median AQI 242009: Median AQI 202010: Median AQI 212011: Median AQI 222012: Median AQI 272013: Median AQI 222014: Median AQI 222015: Median AQI 242016: Median AQI 222017: Median AQI 222018: Median AQI 152019: Median AQI 132020: Median AQI 142021: Median AQI 192022: Median AQI 192023: Median AQI 172024: Median AQI 172025: Median AQI 19198519901995200020052010201520202025
  • 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
Coarse particles (PM10)339100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025339325140000193664PM10
2024274259150000173868PM10
2023354344100000173566PM10
2022356337190000194087PM10
202135134560000193764PM10
2020358346120000143271PM10
201934834800000132646PM10
201833733250000153157PM10
2017365335300000224983PM10
2016352322300000224899PM10
20153533094310002454106PM10
2014357316410000225196PM10
2013355334210000224677PM10
20123462935210002756113PM10
2011285257280000225077PM10
20103082851931002145176PM10
2009360344160000204190PM10
2008360324360000245194PM10
20073573163920002753107PM10
2006364302620000285793PM10
20053642679610003563104PM10
20043653056000002955100PM10
20033522787310002659146PM10
2002351277740000316396PM10
2001358294640000295792PM10
20001641006310004064109PM2.5
1999105485610005374117PM2.5
19986353910003161106PM10
1997244224200000244978PM10
1996323301220000264698PM10
1995336315210000214685PM10
19942312003010002653104PM10
19931701591010002348104PM10
1992179163160000274988PM10
1991166139270000315671PM10
1990169143260000275792PM10
1989176141350000355594PM10
1988172129430000386090PM10
1987316253630000315897PM10
1986331279520000315493PM10
19852862127220003761108PM10

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 Nebraska with a similar median AQI in 2025

All monitored counties in Nebraska

Source: U.S. EPA AirData, “Annual AQI by County” files for 1985–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem