Air quality in Boulder, Colorado, United States of America today

Mr. Duck’s Air Quality Score

Good air today for Boulder, Colorado, United States of America

⚠️ This website is currently under active development. Some data may be incomplete or temporarily inaccurate. For health-critical decisions, please verify information through official government or environmental sources.

Categories follow US EPA AQI breakpoints for PM (estimate from latest valid measurements; this project does not compute EPA NowCast/24-hour AQI yet).

This friendly indicator summarizes the latest city readings. For health guidance, please see: EPA AirNow or WHO.

Air quality today

The air quality in Boulder, Colorado is currently rated as Good. The primary pollutant measured is PM2.5. Seven valid measurements were recorded, with the most recent reading taken on 2026-02-23 12:00 UTC. The reported PM2.5 concentration is 4.0 µg/m³, and the PM10 concentration is 18.0 µg/m³. Both values correspond to the reference levels of 4.0 µg/m³ for PM2.5 and 18.0 µg/m³ for PM10 used in the assessment.

Data is shown via OpenAQ. The dataset reflects the seven valid observations that support the Good category for today’s air quality in Boulder. Across the observations, PM2.5 consistently measured at the reference value, while PM10 also remained at its reference level. This page is informational; for health guidance, use official sources such as EPA AirNow or WHO.

Latest sensor values

PM categories follow US EPA AQI breakpoints, shown here as an estimate derived from the latest valid measurements (this project does not compute EPA NowCast/24-hour AQI yet).

What the data includes

The Boulder data set pulls from five monitoring stations and contains 18 individual rows of measurements. Six pollutants are reported: PM1, PM10, PM2.5, relative humidity, temperature and UM003 (particle count). The most recent readings are all from within the last month, with PM2.5 and PM10 updated on 2026-02-10 23:06 UTC and 2026-02-10 23:00 UTC respectively, while the other four parameters were last refreshed on 2026-01-30 18:00 UTC.

PM2.5 values span the full range from 0.0 µg/m³ up to a peak of 3 685.17 µg/m³ recorded at Marine Street – CU Boulder, with a median of about 3.49 µg/m³ and the 90th percentile near 2 212.70 µg/m³, indicating occasional very high spikes. PM1 measurements are much tighter, ranging from 0.0 µg/m³ to 2.12 µg/m³, a median of 1.29 µg/m³ and a 90th percentile of roughly 1.96 µg/m³. Relative humidity across the sites varies between 26.78 % and 31.59 %, centering on a median of 29.92 %, while temperature shows a modest spread from 10.28 °C to 22.41 °C with a median of 20.83 °C. The UM003 particle count ranges from 46.10 to 196.96 particles/cm³, with a median close to 194.29 particles/cm³, suggesting generally high background particle concentrations.

Coverage is uneven: PM10 appears in only a single row (value 18.0 µg/m³ at Boulder – CU – 2102), whereas the other pollutants have multiple observations across the five stations. Although all data are labeled as updated within 30 days, the older timestamp of 2026-01-30 18:00 UTC for four parameters means that the freshest snapshot is a few weeks older than the PM2.5 and PM10 readings. Consequently, while the dataset offers a recent snapshot of air quality, conditions can still differ by location and time across the city.

Learn more about sources and filtering: About the data.

Trusted references: WHO (Air pollution) · US EPA AirNow · European Environment Agency (Air)

Latest sensor values (bars)

PM categories follow US EPA AQI breakpoints, shown here as an estimate derived from the latest valid measurements (this project does not compute EPA NowCast/24-hour AQI yet).

Data notes

These data are based on seven valid measurements and were updated within 30 days, with the most recent reading recorded on 2026‑02‑10 at 23:00 UTC. The values represent a citywide snapshot and may not reflect conditions at specific neighborhoods or at other times of day. Air quality can vary by location and time within the city.

OpenAQ station rows