Air quality in Castle Rock, Colorado, United States of America today

Mr. Duck’s Air Quality Score

Good air today for Castle Rock, 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 Castle Rock, Colorado is rated as Good today. The primary pollutant identified is PM2.5, fine particulate matter, and the measured concentration is reported at a reference value of 0.0 µg/m³ based on five valid observations.

Data for this assessment are shown via OpenAQ. 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 Castle Rock air‑quality dataset contains five measured variables – PM1, PM2.5, relative humidity, temperature and the particle count UM003 – drawn from a total of seven data rows collected at two monitoring stations in the city. All five pollutants have a most recent timestamp of 2026-02-11 01:00 UTC, so the newest observations are just under two weeks old. However, the freshness profile is uneven: five of the rows (about 71 %) were recorded within the last seven days, while two rows are older than thirty days, meaning a portion of the record reflects conditions that may no longer be current.

The numeric ranges show very limited variation for most parameters. PM1 and relative humidity each have a single observed value – 0.0 µg/m³ for PM1 and 31.54633344014486 % for humidity – with identical minimum, median and maximum values, indicating that only one measurement is available for those variables. UM003 also appears as a single reading of 34.28250010808309 particles/cm³. By contrast, temperature spans a broader interval from –1.36 °C to 10.59 °C, with a median around 4.61 °C and the 10th‑percentile at –0.17 °C, suggesting modest daily swings in the recent period. PM2.5 shows a similarly narrow spread, ranging from 0.0 to 2.0 µg/m³, a median of 1.0 µg/m³ and a 90th‑percentile of 1.8 µg/m³.

Overall, the dataset provides recent but sparse coverage: while temperature and PM2.5 have multiple observations that allow a glimpse of typical conditions, the other three pollutants are represented by single data points, limiting insight into their variability across Castle Rock. Users should keep in mind that air quality can differ by location and time, especially when many rows are older or missing.

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

The data shown for Castle Rock reflects five valid measurements and was updated today (2026‑02‑11T01:00:00+00:00). This snapshot represents the conditions recorded at that time; air quality can vary across different neighborhoods and throughout the day, so values may differ from what you experience elsewhere in the city.

OpenAQ station rows