Air quality in Arnold, Missouri, United States of America today
Mr. Duck’s Air Quality Score
Good air today for Arnold, Missouri, United States of America
This friendly indicator summarizes the latest city readings. For health guidance, please see: EPA AirNow or WHO.
Air quality today
The air quality in Arnold, Missouri is classified as Good today. The primary pollutant measured is PM2.5 (fine particles). Recent observations show a PM2.5 concentration of 6.1 µg/m³ and a PM10 level of 15.0 µg/m³ based on four valid measurements.
These values indicate that the ambient air meets the criteria for the Good category according to OpenAQ data. 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 Arnold, Missouri dataset currently draws from two monitoring stations, each providing a single row of recent observations for six common air‑quality pollutants: nitrogen monoxide (NO), nitrogen dioxide (NO2), total nitrogen oxides (NOX), ozone (O3), particulate matter up to 10 µm (PM10) and fine particulate matter up to 2.5 µm (PM2.5). The freshest record in the set is from 2026‑02‑10 23:00 UTC, when both PM10 and PM2.5 were updated alongside NO, NO2 and NOX; ozone’s latest entry is older, dated 2025‑11‑04 15:00 UTC.
Across the two stations the measured values show a modest spread. Ozone ranges from 0.015 to 0.042 ppm with a median of about 0.029 ppm, while PM10 varies between 13 and 15 µg/m³ (median 14 µg/m³) and PM2.5 sits from 6.1 to 8.7 µg/m³ (median roughly 7.4 µg/m³). The nitrogen species are essentially constant: NO is recorded at –0.002 ppm, NO2 at 0.0023 ppm and NOX at 0.0004 ppm for the single recent sample each.
The data coverage is uneven in time. Only ozone has a timestamp older than six months, whereas all other pollutants were refreshed within the last week, indicating that most of the current picture relies on very recent measurements except for ozone. Because there are just two stations, spatial variation within Arnold cannot be captured; conditions may differ across neighborhoods or at times not represented in these rows.
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 data for Arnold, Missouri is based on four valid measurements and was refreshed recently—updated within three days, with the latest reading recorded at 2026‑02‑10 23:00 UTC. This snapshot reflects conditions at a specific time and place; air quality can differ across neighborhoods and throughout the day, so values may vary locally.
OpenAQ station rows
| Station | Parameter | Value | Unit | Last updated |
|---|---|---|---|---|
| ARNOLD | o3 | 0.042 | ppm | 2016-03-23 19:00 UTC |
| ARNOLD | pm10 | 13.0 | µg/m³ | 2016-03-23 19:00 UTC |
| ARNOLD | pm25 | 8.7 | µg/m³ | 2016-03-23 19:00 UTC |
| Arnold West | no2 | 0.0023 | ppm | 2026-02-10 23:00 UTC |
| Arnold West | nox | 0.0004 | ppm | 2026-02-10 23:00 UTC |
| Arnold West | o3 | 0.015 | ppm | 2025-11-04 15:00 UTC |
| Arnold West | pm10 | 15.0 | µg/m³ | 2026-02-10 23:00 UTC |
| Arnold West | pm25 | 6.1 | µg/m³ | 2026-02-10 23:00 UTC |