Twin Falls, ID

EPA AQS → · NOAA →

Metro area air quality from EPA Air Quality System (2024). 347 days monitored. Median AQI: 23 (Good).

Insights: Twin Falls, ID metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 23 over 347 measured days in 2024, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 264 Good days (76%), 76 Moderate (22%), and 4 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 64 while the highest single-day reading hit 158 (Unhealthy). Metro residents averaged roughly 22.8 clean-air days per 30-day window across the reporting year.

Across the 2020–2024 trend window, good days shifted by -51 and the median AQI moved -1 points, which classifies the multi-year trajectory as worsening. The metro recorded 3 unhealthy-or-worse days combined — on those days the EPA recommends that sensitive groups limit prolonged outdoor exertion, and many schools and athletic programs adjust outdoor activity accordingly. Metros with comparable AQI profiles include Elko, NV (87.1% good, AQI 23); Ellensburg, WA (87.4% good, AQI 23); La Grande, OR (82.8% good, AQI 23).

Air Quality Summary

Median AQI

23

Good

Good Days

76.1%

264 of 347 days

Max AQI

158

Unhealthy

Health Grade

Good

90th pct: 64

AQI Day Breakdown (2024)

Distribution of 347 monitored days across EPA AQI categories.

Good

264

76%

Moderate

76

22%

USG

4

1%

Unhealthy

3

1%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Twin Falls, ID metro area's air quality is rated Good based on 76.1% good air days. There were 3 unhealthy days in 2024 when outdoor activity should be limited.

Air quality is acceptable most days, but 4 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 158. Sensitive groups should monitor real-time conditions at AirNow.gov.

5-Year Air Quality Trend

Air quality is worsening in the Twin Falls, ID metro. Best year: 2023 (328 good days).

Year Good Moderate Unhealthy Median AQI
2020 315 44 4 24
2021 298 56 0 28
2022 280 71 1 31
2023 328 16 0 25
2024 264 76 3 23

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Twin Falls, ID.

Elko, NV

AQI 23 · 87.1% good

23

Ellensburg, WA

AQI 23 · 87.4% good

23

La Grande, OR

AQI 23 · 82.8% good

23

Lubbock, TX

AQI 23 · 92.2% good

23

The Dalles, OR

AQI 23 · 87.1% good

23

Aberdeen, SD

AQI 24 · 85.7% good

24

Related Environmental & Health Data

Explore related data for the Twin Falls, ID area from other federal sources.

🏭

PlainEnviro — EPA Facilities

EPA environmental compliance data for regulated facilities. 5-year violation trends.

🏥

PlainHealth — Mortality Data

CDC NCHS leading causes of death. 19 years of mortality data by cause.

🌡️

PlainClimate — Climate Normals

NOAA 30-year climate normals. Temperature, precipitation, humidity.

⚠️

PlainHazard — Natural Disasters

FEMA disaster declarations. Wildfire, flood, and storm history affecting air quality. FEMA.gov →

Air Quality Guides

Learn more about air quality monitoring, pollutants, and health impacts.

Understanding AQI

What each AQI level means and who is most at risk.

Best & Worst City Air Quality

Metro area air quality rankings and what drives urban pollution.

Health Effects of Air Pollution

How PM2.5 and ozone exposure affects respiratory and cardiovascular health.

Frequently Asked Questions

What is the air quality in the Twin Falls, ID metro area? ▼
The Twin Falls, ID metro area has a median Air Quality Index (AQI) of 23, rated "Good." 76.1% of monitored days (264 out of 347) had good air quality in 2024.
How many unhealthy air days does Twin Falls, ID have? ▼
In 2024, the Twin Falls, ID metro area recorded 3 unhealthy air days (3 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 158.
Is air quality in Twin Falls, ID getting better or worse? ▼
Air quality in the Twin Falls, ID metro is worsening based on 5-year trends (2020-2024). Best year: 2023 with 328 good days. Worst year: 2024 with 264 good days.
What does AQI 23 mean for health? ▼
An AQI of 23 is "Good" — air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
What is the 90th percentile AQI for Twin Falls, ID? ▼
The 90th percentile AQI for the Twin Falls, ID metro area is 64, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 158 (Unhealthy).
How does Twin Falls, ID compare to other metro areas? ▼
The Twin Falls, ID metro has 76.1% good air days. Similar metros: Elko, NV (87.1% good), Ellensburg, WA (87.4% good), La Grande, OR (82.8% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2024. The AQS collects ambient air monitoring data from state, local, and tribal monitoring agencies across the United States.

Metrics: Air Quality Index (AQI) is calculated using EPA-standard breakpoints for six criteria pollutants: PM2.5, PM10, Ozone, NO2, CO, and SO2. Median AQI, max AQI, and 90th percentile AQI are computed from daily measurements. Good days percentage reflects days with AQI 0–50.

Coverage: 501 metro areas (Core Based Statistical Areas). Only metros with active monitoring stations are included. Unmonitored areas are not represented.

Read our methodology — how this data is sourced, computed, and verified.

Source: U.S. EPA — AirNow / AQS Air Quality Index readings and pollutant concentrations · 2025