A scatterplot for the Los Angeles area compares PM2.5 air pollution levels (x-axis) against a user-selectable income or health attribute from a dataset of regional census tracts. Using D3 v5, the visualization loads a CSV and converts its string columns to numbers. Animated circles transition between positions when the user changes the y-axis variable through a dropdown menu. The chart relies on D3's `scaleLinear`, `extent`, `axisLeft`, and `axisBottom` APIs to render scales and axes.