This visualization shows the average Air Quality Index (AQI) for six pollutants—CO, NO2, SO2, PM10, PM2.5, and Ozone—as a pie chart with a custom legend listing each pollutant and its mean value in units. The code loads a CSV dataset from a GitHub gist, aggregates the pollutant-specific AQI values by summing and averaging non-void entries, and renders the result using D3 v5’s `pie`, `arc`, and `scaleOrdinal` with `schemeCategory10`. The SVG is drawn with paths, and each segment includes a mouseover handler that logs the pollutant’s AQI to the console.