EnviroNearby

Ada County, Idaho air quality history

Daily Air Quality Index summaries from EPA monitors in Ada, Idaho, 1980–2025.

74%
Good days in 2025
42
Median daily AQI, 2025
0
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 Ada, Idaho on 365 days. 270 of those days (74%) were in the Good range, and the median daily AQI was 42. That median is higher than the typical monitored county in Idaho (median 35 across 18 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 209 days. Across the years with fuller monitoring, the share of Good days rose: an average of 41% in 1980–1982 versus 69% 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 139 of 366 days1980: Moderate 204 of 366 days1980: Unhealthy for Sensitive Groups 22 of 366 days1980: Unhealthy 1 of 366 days19801981: Good 117 of 295 days1981: Moderate 162 of 295 days1981: Unhealthy for Sensitive Groups 16 of 295 days1982: Good 166 of 364 days1982: Moderate 185 of 364 days1982: Unhealthy for Sensitive Groups 11 of 364 days1982: Unhealthy 2 of 364 days1983: Good 114 of 243 days1983: Moderate 120 of 243 days1983: Unhealthy for Sensitive Groups 6 of 243 days1983: Unhealthy 1 of 243 days1983: Very Unhealthy 2 of 243 days1984: Good 261 of 364 days1984: Moderate 97 of 364 days1984: Unhealthy for Sensitive Groups 6 of 364 days1985: Good 256 of 356 days1985: Moderate 97 of 356 days1985: Unhealthy for Sensitive Groups 3 of 356 days19851986: Good 190 of 330 days1986: Moderate 137 of 330 days1986: Unhealthy for Sensitive Groups 2 of 330 days1986: Unhealthy 1 of 330 days1987: Good 237 of 344 days1987: Moderate 106 of 344 days1987: Unhealthy 1 of 344 days1988: Good 277 of 358 days1988: Moderate 80 of 358 days1988: Unhealthy for Sensitive Groups 1 of 358 days1989: Good 246 of 328 days1989: Moderate 82 of 328 days1990: Good 118 of 201 days1990: Moderate 83 of 201 days19901991: Good 258 of 356 days1991: Moderate 96 of 356 days1991: Unhealthy for Sensitive Groups 2 of 356 days1992: Good 265 of 366 days1992: Moderate 101 of 366 days1993: Good 293 of 357 days1993: Moderate 64 of 357 days1994: Good 219 of 254 days1994: Moderate 35 of 254 days1995: Good 325 of 363 days1995: Moderate 38 of 363 days19951996: Good 332 of 366 days1996: Moderate 34 of 366 days1997: Good 330 of 365 days1997: Moderate 34 of 365 days1997: Unhealthy for Sensitive Groups 1 of 365 days1998: Good 335 of 365 days1998: Moderate 30 of 365 days1999: Good 297 of 365 days1999: Moderate 66 of 365 days1999: Unhealthy for Sensitive Groups 2 of 365 days2000: Good 301 of 366 days2000: Moderate 60 of 366 days2000: Unhealthy for Sensitive Groups 5 of 366 days20002001: Good 226 of 365 days2001: Moderate 119 of 365 days2001: Unhealthy for Sensitive Groups 16 of 365 days2001: Unhealthy 4 of 365 days2002: Good 224 of 365 days2002: Moderate 125 of 365 days2002: Unhealthy for Sensitive Groups 14 of 365 days2002: Unhealthy 2 of 365 days2003: Good 269 of 362 days2003: Moderate 87 of 362 days2003: Unhealthy for Sensitive Groups 6 of 362 days2004: Good 235 of 366 days2004: Moderate 124 of 366 days2004: Unhealthy for Sensitive Groups 7 of 366 days2005: Good 226 of 365 days2005: Moderate 131 of 365 days2005: Unhealthy for Sensitive Groups 8 of 365 days20052006: Good 189 of 365 days2006: Moderate 150 of 365 days2006: Unhealthy for Sensitive Groups 24 of 365 days2006: Unhealthy 2 of 365 days2007: Good 160 of 365 days2007: Moderate 187 of 365 days2007: Unhealthy for Sensitive Groups 15 of 365 days2007: Unhealthy 3 of 365 days2008: Good 194 of 366 days2008: Moderate 166 of 366 days2008: Unhealthy for Sensitive Groups 6 of 366 days2009: Good 169 of 365 days2009: Moderate 189 of 365 days2009: Unhealthy for Sensitive Groups 7 of 365 days2010: Good 102 of 365 days2010: Moderate 259 of 365 days2010: Unhealthy for Sensitive Groups 4 of 365 days20102011: Good 276 of 365 days2011: Moderate 84 of 365 days2011: Unhealthy for Sensitive Groups 5 of 365 days2012: Good 265 of 366 days2012: Moderate 90 of 366 days2012: Unhealthy for Sensitive Groups 9 of 366 days2012: Unhealthy 1 of 366 days2012: Very Unhealthy 1 of 366 days2013: Good 268 of 365 days2013: Moderate 82 of 365 days2013: Unhealthy for Sensitive Groups 11 of 365 days2013: Unhealthy 4 of 365 days2014: Good 277 of 365 days2014: Moderate 87 of 365 days2014: Unhealthy 1 of 365 days2015: Good 276 of 365 days2015: Moderate 80 of 365 days2015: Unhealthy for Sensitive Groups 7 of 365 days2015: Unhealthy 2 of 365 days20152016: Good 271 of 366 days2016: Moderate 88 of 366 days2016: Unhealthy for Sensitive Groups 7 of 366 days2017: Good 217 of 365 days2017: Moderate 126 of 365 days2017: Unhealthy for Sensitive Groups 18 of 365 days2017: Unhealthy 4 of 365 days2018: Good 266 of 365 days2018: Moderate 92 of 365 days2018: Unhealthy for Sensitive Groups 7 of 365 days2019: Good 266 of 365 days2019: Moderate 99 of 365 days2020: Good 242 of 366 days2020: Moderate 106 of 366 days2020: Unhealthy for Sensitive Groups 11 of 366 days2020: Unhealthy 7 of 366 days20202021: Good 223 of 365 days2021: Moderate 124 of 365 days2021: Unhealthy for Sensitive Groups 15 of 365 days2021: Unhealthy 3 of 365 days2022: Good 196 of 365 days2022: Moderate 162 of 365 days2022: Unhealthy for Sensitive Groups 6 of 365 days2022: Unhealthy 1 of 365 days2023: Good 251 of 365 days2023: Moderate 111 of 365 days2023: Unhealthy for Sensitive Groups 3 of 365 days2024: Good 230 of 366 days2024: Moderate 101 of 366 days2024: Unhealthy for Sensitive Groups 28 of 366 days2024: Unhealthy 6 of 366 days2024: Very Unhealthy 1 of 366 days2025: Good 270 of 365 days2025: Moderate 95 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 931981: 90th percentile AQI 921982: 90th percentile AQI 871983: 90th percentile AQI 811984: 90th percentile AQI 731985: 90th percentile AQI 701986: 90th percentile AQI 771987: 90th percentile AQI 691988: 90th percentile AQI 611989: 90th percentile AQI 641990: 90th percentile AQI 651991: 90th percentile AQI 661992: 90th percentile AQI 631993: 90th percentile AQI 581994: 90th percentile AQI 541995: 90th percentile AQI 511996: 90th percentile AQI 491997: 90th percentile AQI 491998: 90th percentile AQI 461999: 90th percentile AQI 572000: 90th percentile AQI 602001: 90th percentile AQI 792002: 90th percentile AQI 842003: 90th percentile AQI 672004: 90th percentile AQI 772005: 90th percentile AQI 742006: 90th percentile AQI 932007: 90th percentile AQI 872008: 90th percentile AQI 712009: 90th percentile AQI 772010: 90th percentile AQI 722011: 90th percentile AQI 642012: 90th percentile AQI 672013: 90th percentile AQI 712014: 90th percentile AQI 612015: 90th percentile AQI 642016: 90th percentile AQI 682017: 90th percentile AQI 872018: 90th percentile AQI 722019: 90th percentile AQI 582020: 90th percentile AQI 762021: 90th percentile AQI 792022: 90th percentile AQI 752023: 90th percentile AQI 642024: 90th percentile AQI 972025: 90th percentile AQI 611980: Median AQI 571981: Median AQI 551982: Median AQI 531983: Median AQI 511984: Median AQI 391985: Median AQI 401986: Median AQI 441987: Median AQI 391988: Median AQI 341989: Median AQI 411990: Median AQI 451991: Median AQI 401992: Median AQI 401993: Median AQI 321994: Median AQI 331995: Median AQI 301996: Median AQI 301997: Median AQI 351998: Median AQI 351999: Median AQI 372000: Median AQI 332001: Median AQI 452002: Median AQI 452003: Median AQI 402004: Median AQI 442005: Median AQI 442006: Median AQI 482007: Median AQI 542008: Median AQI 492009: Median AQI 542010: Median AQI 552011: Median AQI 432012: Median AQI 412013: Median AQI 382014: Median AQI 412015: Median AQI 412016: Median AQI 412017: Median AQI 462018: Median AQI 422019: Median AQI 412020: Median AQI 442021: Median AQI 462022: Median AQI 482023: Median AQI 442024: Median AQI 442025: 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
Ozone20957%
Fine particles (PM2.5)15342%
Coarse particles (PM10)31%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025365270950000426197Ozone
2024366230101286104497214Ozone
202336525111130004464120Ozone
202236519616261004875166Ozone
2021365223124153004679173Ozone
2020366242106117004476198PM2.5
20193652669900004158100Ozone
20183652669270004272134Ozone
2017365217126184004687196Ozone
20163662718870004168116Ozone
20153652768072004164172Ozone
20143652778701004161152Ozone
201336526882114003871194Ozone
20123662659091104167215Ozone
20113652768450004364115Ozone
201036510225940005572136PM2.5
200936516918970005477126PM2.5
200836619416660004971147PM2.5
2007365160187153005487172PM2.5
2006365189150242004893161PM2.5
200536522613180004474147PM2.5
200436623512470004477120Ozone
20033622698760004067143Ozone
2002365224125142004584156Ozone
2001365226119164004579155PM2.5
20003663016050003360108PM10
19993652976620003757149NO2
1998365335300000354698NO2
19973653303410003549104NO2
1996366332340000304980CO
1995363325380000305187CO
1994254219350000335489CO
1993357293640000325887CO
19923662651010000406393CO
19913562589620004066110CO
1990201118830000456587CO
19893282468200004164100CO
19883582778010003461106CO
198734423710601003969173CO
198633019013721004477180CO
19853562569730004070108CO
19843642619760003973113CO
198324311412061205181202CO
1982364166185112005387192CO
1981295117162160005592147CO
1980366139204221005793151CO

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 Idaho with a similar median AQI in 2025

All monitored counties in Idaho

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