Air quality in Chelsea, Massachusetts, United States of America today

Mr. Duck’s Air Quality Score

Good air today for Chelsea, Massachusetts, 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 Chelsea, Massachusetts is classified as Good today. The primary pollutant identified is PM2.5 (fine particles).

A single valid measurement recorded a PM2.5 concentration of 5.9 µg/m³. No PM10 value is available for this assessment. 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

Chelsea’s OpenAQ feed includes six measured pollutants: PM2.5, PM1, PM10, relative humidity, temperature and UM003 (particle count). The dataset comprises twelve individual rows drawn from three monitoring stations, but the timing of those observations is uneven. Only one row was recorded within the past seven days; the remaining eleven are classified as either older than a month (six rows) or of unknown recency (five rows). Consequently, the freshest data point in the whole set is the PM2.5 measurement from Chelsea HP on 2026‑02‑11 00:00 UTC, while all other pollutants – PM1, PM10, relative humidity, temperature and UM003 – were last updated on 2025‑01‑13 23:00 UTC.

The values themselves show a modest spread for most constituents. PM2.5 ranges from a low of 5.9 µg/m³ to a high of about 25 µg/m³, with a median near 6.1 µg/m³, indicating that recent observations are clustered toward the lower end of the range. PM1 varies more widely, from roughly 2.7 µg/m³ up to 14.3 µg/m³ and sits at a median of 8.5 µg/m³, suggesting greater fluctuation across locations or times. Relative humidity stays between about 38 % and 52 %, centered around 45 %; temperature spans from near‑freezing 8.5 °C to warm 29.5 °C, with a median close to 19 °C; UM003 particle counts range from roughly 383 particles/cm³ to 2,218 particles/cm³, medially about 1,300. PM10 is represented by a single value of 26.5 µg/m³, so no spread can be assessed for that metric.

Overall the dataset provides a snapshot of multiple air‑quality parameters for Chelsea, but the predominance of older or unknown‑date rows limits how fully current conditions are captured. Users should keep in mind that actual pollutant levels may differ across neighborhoods and times not reflected in these sparse, dated observations.

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 current reading for Chelsea, Massachusetts is based on a single valid measurement and was updated today (2026‑02‑11T00:00:00+00:00). This snapshot reflects conditions at the time of collection; air quality can vary across different neighborhoods and throughout the day, so values may differ from one location to another within the city.

OpenAQ station rows