Air quality in Alton, Illinois, United States of America today
Mr. Duck’s Air Quality Score
Good air today for Alton, Illinois, 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 Alton, Illinois is currently classified as Good. The primary pollutant identified for today is PM2.5 (fine particles).
A single valid measurement recorded a PM2.5 concentration of 6.9 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
Alton’s air‑quality profile draws from a single monitoring station that reports two pollutants: ozone (O3) and fine particulate matter (PM2.5). The dataset contains two rows—one for each pollutant—so the coverage is limited to this lone site.
The most recent measurement in the set is the PM2.5 reading, recorded on 2026‑02‑10 at 23:00 UTC, while the ozone value dates back to 2025‑11‑04 at 14:00 UTC. This means that for ozone the data are more than three months old, whereas the particulate matter figure is current within the last week. Overall, the freshest timestamp across all rows is from early February 2026.
Both pollutants show a single observed value with no variation in the record. Ozone was measured at 0.008 ppm, and that same concentration appears as the minimum, median, maximum, 10th percentile and 90th percentile for the pollutant. Likewise, PM2.5 registered a consistent 6.9 µg/m³ across all statistical markers. Because each pollutant has only one data point, there is no spread to describe and the typical (median) value equals the sole recorded measurement.
Given that the dataset consists of just one station and two rows, the picture of Alton’s air quality is necessarily narrow. The ozone reading is relatively old, so conditions could have changed since its last capture, while the PM2.5 figure reflects a more up‑to‑date snapshot. Users should keep in mind that air quality can differ across neighborhoods and over time, and the available data represent only these specific moments at a single location.
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 Alton, Illinois reflects a single valid measurement and was updated within 3 days, with the most recent reading recorded at 2026‑02‑10T23:00:00+00:00. This snapshot provides a brief view of current conditions; however, air quality can differ across neighborhoods and change throughout the day, so local variations may not be captured in this single data point.
OpenAQ station rows
| Station | Parameter | Value | Unit | Last updated |
|---|---|---|---|---|
| Alton | o3 | 0.008 | ppm | 2025-11-04 14:00 UTC |
| Alton | pm25 | 6.9 | µg/m³ | 2026-02-10 23:00 UTC |