This interactive scatter plot visualizes monthly roadside pollution levels in London from January 2010 through August 2018, sourced from the Kings College London Air Quality Dataset. Each circle represents a monthly average, colored by pollutant type, with a legend that filters data on click. The visualization includes animated transitions using `transition().duration()` and `delay()`, a dropdown menu for selecting variables, and D3 v5 APIs including `scaleTime`, `scaleLinear`, `axisBottom`, and `axisLeft`. The chart renders as an SVG with interactive color legend and axis labels.