EnviroNearby

Valley County, Idaho air quality history

Daily Air Quality Index summaries from EPA monitors in Valley, Idaho, 2002–2025.

73%
Good days in 2025
34
Median daily AQI, 2025
1
Days above 100 in 2025
352
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Valley, Idaho on 352 days. 258 of those days (73%) were in the Good range, and the median daily AQI was 34. That median is about the same as the typical monitored county in Idaho (median 35 across 18 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 352 days. Across the years with fuller monitoring, the share of Good days rose: an average of 62% in 2004–2007 versus 70% in 2023–2025.

Years with fewer than 120 monitored days (2002, 2003, 2006) 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%2002: Good 8 of 15 days2002: Moderate 7 of 15 days20022003: Good 35 of 41 days2003: Moderate 6 of 41 days2004: Good 194 of 250 days2004: Moderate 56 of 250 days20042005: Good 216 of 328 days2005: Moderate 109 of 328 days2005: Unhealthy for Sensitive Groups 3 of 328 days2006: Good 55 of 113 days2006: Moderate 54 of 113 days2006: Unhealthy for Sensitive Groups 2 of 113 days2006: Unhealthy 2 of 113 days20062007: Good 73 of 167 days2007: Moderate 83 of 167 days2007: Unhealthy for Sensitive Groups 10 of 167 days2007: Unhealthy 1 of 167 days2008: Good 157 of 190 days2008: Moderate 33 of 190 days20082009: Good 278 of 328 days2009: Moderate 50 of 328 days2015: Good 214 of 247 days2015: Moderate 28 of 247 days2015: Unhealthy for Sensitive Groups 2 of 247 days2015: Unhealthy 3 of 247 days20152016: Good 304 of 348 days2016: Moderate 44 of 348 days2017: Good 244 of 362 days2017: Moderate 106 of 362 days2017: Unhealthy for Sensitive Groups 6 of 362 days2017: Unhealthy 6 of 362 days20172018: Good 254 of 353 days2018: Moderate 97 of 353 days2018: Unhealthy for Sensitive Groups 2 of 353 days2019: Good 261 of 357 days2019: Moderate 96 of 357 days20192020: Good 205 of 329 days2020: Moderate 117 of 329 days2020: Unhealthy for Sensitive Groups 5 of 329 days2020: Unhealthy 1 of 329 days2020: Very Unhealthy 1 of 329 days2021: Good 217 of 351 days2021: Moderate 125 of 351 days2021: Unhealthy for Sensitive Groups 7 of 351 days2021: Unhealthy 2 of 351 days20212022: Good 241 of 351 days2022: Moderate 102 of 351 days2022: Unhealthy for Sensitive Groups 6 of 351 days2022: Unhealthy 2 of 351 days2023: Good 255 of 360 days2023: Moderate 105 of 360 days20232024: Good 235 of 357 days2024: Moderate 113 of 357 days2024: Unhealthy for Sensitive Groups 8 of 357 days2024: Unhealthy 1 of 357 days2025: Good 258 of 352 days2025: Moderate 93 of 352 days2025: Unhealthy for Sensitive Groups 1 of 352 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 year0501002002: 90th percentile AQI 742003: 90th percentile AQI 512004: 90th percentile AQI 552005: 90th percentile AQI 632006: 90th percentile AQI 782007: 90th percentile AQI 832008: 90th percentile AQI 532009: 90th percentile AQI 542015: 90th percentile AQI 532016: 90th percentile AQI 522017: 90th percentile AQI 682018: 90th percentile AQI 622019: 90th percentile AQI 662020: 90th percentile AQI 682021: 90th percentile AQI 722022: 90th percentile AQI 692023: 90th percentile AQI 612024: 90th percentile AQI 702025: 90th percentile AQI 602002: Median AQI 442003: Median AQI 342004: Median AQI 342005: Median AQI 392006: Median AQI 522007: Median AQI 542008: Median AQI 352009: Median AQI 312015: Median AQI 182016: Median AQI 172017: Median AQI 302018: Median AQI 292019: Median AQI 292020: Median AQI 402021: Median AQI 412022: Median AQI 372023: Median AQI 362024: Median AQI 372025: Median AQI 342002200420062008201520172019202120232025
  • 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)352100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253522589310003460104PM2.5
202435723511381003770155PM2.5
20233602551050000366178PM2.5
202235124110262003769168PM2.5
202135121712572004172162PM2.5
202032920511751104068211PM2.5
2019357261960000296692PM2.5
20183532549720002962108PM2.5
201736224410666003068192PM2.5
2016348304440000175290PM2.5
20152472142823001853154PM2.5
2009328278500000315484PM2.5
2008190157330000355373PM2.5
20071677383101005483161PM2.5
2006113555422005278157PM2.5
200532821610930003963132PM2.5
2004250194560000345597PM2.5
2003413560000345177PM2.5
200215870000447475PM2.5

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 2002–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem