What if we could hear air pollution?

This website turns air quality data into sound. 

We used data from 7 major cities using the 2018 Air Quality Index (AQI), a metric run by the Environmental Protection Agency (EPA). The AQI is one number, from 1 to 500, that captures the daily air quality in a city based on the five air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide.

Each AQI data point has been converted into a musical chord. The lower the number, indicating good air quality, the more clearly you can hear the sound.