EnviroNearby

Blaine County, Idaho air quality history

Daily Air Quality Index summaries from EPA monitors in Blaine, Idaho, 1990–2025.

97%
Good days in 2025
17
Median daily AQI, 2025
0
Days above 100 in 2025
350
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Blaine, Idaho on 350 days. 338 of those days (97%) were in the Good range, and the median daily AQI was 17. That median is lower than 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 350 days. Across the years with fuller monitoring, the share of Good days rose: an average of 90% in 2015–2018 versus 94% in 2023–2025.

Years with fewer than 120 monitored days (1995, 1996, 1997, 1998, 1999, 2016…) 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%1990: Good 14 of 14 days19901991: Good 29 of 29 days1992: Good 14 of 14 days19921995: Good 58 of 58 days1996: Good 56 of 57 days1996: Moderate 1 of 57 days19961997: Good 59 of 60 days1997: Moderate 1 of 60 days1998: Good 56 of 58 days1998: Moderate 2 of 58 days19981999: Good 56 of 59 days1999: Moderate 3 of 59 days2015: Good 192 of 202 days2015: Moderate 8 of 202 days2015: Unhealthy for Sensitive Groups 2 of 202 days20152016: Good 97 of 113 days2016: Moderate 16 of 113 days2017: Good 197 of 220 days2017: Moderate 18 of 220 days2017: Unhealthy for Sensitive Groups 4 of 220 days2017: Unhealthy 1 of 220 days20172018: Good 313 of 363 days2018: Moderate 47 of 363 days2018: Unhealthy for Sensitive Groups 3 of 363 days2019: Good 307 of 314 days2019: Moderate 7 of 314 days20192020: Good 323 of 365 days2020: Moderate 34 of 365 days2020: Unhealthy for Sensitive Groups 6 of 365 days2020: Unhealthy 2 of 365 days2021: Good 288 of 350 days2021: Moderate 52 of 350 days2021: Unhealthy for Sensitive Groups 10 of 350 days20212022: Good 321 of 355 days2022: Moderate 29 of 355 days2022: Unhealthy for Sensitive Groups 2 of 355 days2022: Unhealthy 3 of 355 days2023: Good 323 of 330 days2023: Moderate 7 of 330 days20232024: Good 310 of 359 days2024: Moderate 43 of 359 days2024: Unhealthy for Sensitive Groups 4 of 359 days2024: Unhealthy 1 of 359 days2024: Very Unhealthy 1 of 359 days2025: Good 338 of 350 days2025: Moderate 12 of 350 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 year0501001990: 90th percentile AQI 331991: 90th percentile AQI 181992: 90th percentile AQI 261995: 90th percentile AQI 271996: 90th percentile AQI 321997: 90th percentile AQI 351998: 90th percentile AQI 391999: 90th percentile AQI 342015: 90th percentile AQI 342016: 90th percentile AQI 612017: 90th percentile AQI 532018: 90th percentile AQI 552019: 90th percentile AQI 332020: 90th percentile AQI 532021: 90th percentile AQI 662022: 90th percentile AQI 492023: 90th percentile AQI 332024: 90th percentile AQI 572025: 90th percentile AQI 361990: Median AQI 131991: Median AQI 121992: Median AQI 221995: Median AQI 171996: Median AQI 151997: Median AQI 211998: Median AQI 191999: Median AQI 222015: Median AQI 132016: Median AQI 102017: Median AQI 152018: Median AQI 172019: Median AQI 202020: Median AQI 192021: Median AQI 232022: Median AQI 232023: Median AQI 192024: Median AQI 192025: Median AQI 171990199219961998201520172019202120232025
  • 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)350100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025350338120000173675PM2.5
20243593104341101957220PM2.5
202333032370000193363PM2.5
20223553212923002349182PM2.5
202135028852100002366144PM2.5
20203653233462001953172PM2.5
201931430770000203357PM2.5
20183633134730001755143PM2.5
20172201971841001553166PM2.5
201611397160000106193PM2.5
2015202192820001334138PM2.5
1999595630000223456PM10
1998585620000193972PM10
1997605910000213552PM10
1996575610000153259PM10
1995585800000172736PM10
1992141400000222631PM10
1991292900000121825PM10
1990141400000133343PM10

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 1990–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem