Chicago Air Quality Hourly Sensor Aggregations

277 sensors deployed by the City of Chicago measure fine particulate matter (PM2.5) and nitrogen dioxide (NO2) concentrations. The dataset provides hourly mean, NowCast, and 24-hour rolling mean aggregations for these pollutants, with some sensors also collecting black carbon and weather data. It is published by data.cityofchicago.org and was last updated in April 2026.

Use Cases

• Modeling PM2.5 NowCast concentrations from sensor_name and startofperiod to generate public air quality alerts.
• Analyzing spatial patterns of NO2 pollution across Chicago using location, Zip Codes, and Community Areas columns.
• Correlating atmospheric conditions like atmPressure1HourMean.value with pollutant levels for meteorological studies.
• Investigating fossil fuel combustion sources by analyzing the bcFossilFuel1HourMean.value column from specific sensors.
• Temporal trend analysis of PM2.5 using the pm2_5ConcMassNowcast.value and the hourly mean aggregations.

Strengths

• Data from a network of 277 deployed sensors provides spatial coverage across Chicago.
• Includes multiple aggregation types (1-hour mean, NowCast, 24-hour rolling mean) for specialized trend analysis.
• Automated data quality control checks are applied, as noted in the description.

Limitations

• Black carbon metrics are explicitly noted as offline and unavailable, appearing as blank values in columns like bcBiomass1HourMean.value.
• The dataset is limited to measurements passing automated QC, potentially excluding raw, unvalidated data points.
• Key metadata such as total row count, precise temporal coverage, and sensor uptime are unknown.

Provenance

Source

City of Chicago via data.cityofchicago.org, part of the Open Air Chicago project.

Collection Method

Measurements collected from 277 Clarity air quality sensors deployed throughout the city, with automated cloud calibration for some metrics.

Freshness

Dataset was last updated on 2026-04-03.

Geography

City of Chicago, Illinois, USA.