Air quality in Decatur, Illinois, United States of America today
Mr. Duck’s Air Quality Score
Moderate air today for Decatur, 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 Decatur, Illinois is currently classified as Moderate. The primary pollutant identified is PM2.5 (fine particles), with a measured concentration of 10.8 µg/m³ based on two valid observations reported through OpenAQ.
Data for this assessment are limited to the available measurements and do not include other pollutants such as PM10. 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 Decatur air‑quality record includes two measured pollutants: ozone (O₃) and fine particulate matter (PM₂.5). The dataset comes from a single monitoring location, so all values represent one row of observations for each pollutant. Freshness varies between the two chemicals. The most recent ozone reading is dated 2025‑11‑04 14:00 UTC, which the source labels as “Old data,” indicating that this measurement is more than seven days old. In contrast, the latest PM₂.5 value was recorded on 2026‑02‑10 23:00 UTC and is marked as having been updated within the past week.
Because only one station contributes data, coverage across the city is limited to that specific site. The ozone concentration is a constant 0.016 ppm for the available record; there is no spread in the minimum, median or maximum values—all are identical at 0.016 ppm. PM₂.5 shows a single reported value of 5.2 µg/m³, again with no variation across statistical percentiles. This uniformity reflects the sparse nature of the dataset rather than any inherent stability in ambient conditions.
Overall, the data set provides a snapshot rather than a comprehensive picture of Decatur’s air quality. The ozone metric is outdated, while the particulate matter reading is relatively recent but still originates from only one location. Consequently, city‑wide conditions may differ from these point measurements depending on time of day, weather patterns, and local emission sources. Users should keep in mind that the available figures represent limited spatial and temporal coverage.
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 Decatur air‑quality data are based on two valid measurements and were updated within three days, with the latest refresh recorded at 2026‑02‑10T23:00:00+00:00. This snapshot reflects conditions at a specific time and place; actual pollutant levels can differ across neighborhoods and throughout the day, so values may vary locally and temporally.
OpenAQ station rows
| Station | Parameter | Value | Unit | Last updated |
|---|---|---|---|---|
| DECATUR | o3 | 0.016 | ppm | 2025-11-04 14:00 UTC |
| DECATUR | pm25 | 5.2 | µg/m³ | 2026-02-10 23:00 UTC |