In European cities, a simpler presentation of air quality data is accomplished using various different indices, each converting their measurements into one easily understood number. In our monitoring system, we use the hourly index, which describes the current air quality based on the average of all measurements from the last hour. The platform updates its data on average every 3 minutes, so the measurements shown are the rolling average of the last full hour.

The air quality index used in Europe, CAQI, has five ranges, with the values presented on a scale from 0 (very low) to >100 (very high). It is a relative measure of the amount of air pollution.

In Airly, when providing the CAQI index, we consider PM10 and PM2.5 dust.

To show the differences in air pollution, a colored 7-level scale operates on our platform. This starts with green, which indicates very good quality air. The scale graduates all the way through to maroon, which shows the air pollution standards are being repeatedly exceeded and it would be wise to stay indoors!