This interactive visualization shows air pollution levels across multiple monitoring stations, displaying daily average concentrations for six pollutants (SO2, NO2, O3, CO, PM10, PM2.5) as a series of stacked horizon charts. Users select a year and band number via dropdown menus, which updates React state and triggers D3 to re-render the SVG. The code uses `d3.csv` to load air pollution data from a remote server, `d3.scaleTime` and `d3.scaleLinear` for axes, and `d3.mean` to aggregate hourly measurements into daily averages. Each pollutant uses a distinct color scheme, with bands overlaid to encode magnitude.