Air quality in Chicago, Illinois, United States of America today

Mr. Duck’s Air Quality Score

Moderate air today for Chicago, Illinois, 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 Chicago today is classified as Moderate. The primary pollutant identified is PM2.5 (fine particles). Measurements show a PM2.5 reference value of 34.20 µg/m³ and a PM10 reference value of 18.0 µg/m³, based on 35 valid observations collected via OpenAQ.

These values reflect the current monitoring data for the city. 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

Chicago’s OpenAQ feed includes seven measured pollutants: ozone (O₃), PM1, PM2.5, PM10, relative humidity, temperature and particle count (UM003). The dataset contains 81 individual rows drawn from 17 monitoring stations across the city. Most of the data are recent – the latest updates for PM2.5, PM1, relative humidity, temperature, UM003 and PM10 were recorded on 2026‑02‑11 or 2026‑02‑10, all within the past week. Ozone is an outlier: its only available reading dates back to 2025‑11‑04, so it reflects older conditions.

Across the recent measurements, values show a wide spread. PM2.5 concentrations range from about 1.6 µg/m³ up to 267 µg/m³, with a median near 21.5 µg/m³; PM1 varies between roughly 3.1 and 139 µg/m³, median 9.3 µg/m³. Relative humidity spans 35.6 % to 58 %, centering around 45.6 %; temperature covers 4.7 °C to 31.1 °C, with a typical value near 13 °C. Particle counts (UM003) are especially variable, from roughly 495 to over 32 000 particles/cm³, median about 808. PM10 data are limited to five rows but still show a range from 1.6 to 22.2 µg/m³, median 2.6 µg/m³.

The coverage is uneven: while most pollutants have dozens of recent rows (e.g., 19 rows for PM2.5 and 14 rows each for PM1, humidity, temperature and UM003), PM10 appears in only five rows and ozone in a single, older row. Consequently, city‑wide conditions can differ noticeably by location and time, especially where data are sparse or outdated.

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 reflects 35 valid measurements and was Updated today (last refreshed at 2026-02-11T01:00:00+00:00). These values represent a snapshot of ambient conditions across Chicago, Illinois, but air quality can vary by location and time within the city, so individual neighborhoods may experience different levels than those reported here.

OpenAQ station rows