How bad are high pollution events by metro area?

This map shows high pollution events over the past 10 years (2014-2023) in each major US metro area. More specifically, it is an average of 10 years of 90th percentile AQI data for each major United States metro area. In other words, on 90% of the days in the year, the AQI will be lower than this value, and only on the worst 10% of days will the AQI exceed this level. The darker color is better air quality and the lighter color is poorer air quality. Generally, an AQI of 0-50 is considered good (I believe 0-30 is actually good), 50-100 is moderate, 101+ is unhealthy. Anyway, the coloration is log-scaled for easier interpretation. You can mouse over each dot to see a given location’s data.

How did I make these maps? First, I gathered and organized a massive amount of data from various sources, then used Python to analyze the data, then Folium to create interactive maps.

The map uses data from the Environmental Protection Agency (EPA), specifically their Air Quality System (AQS). The annual AQI data by CBSA and the site coordinates (latitude, longitude, location setting, etc.) were pulled from EPA’s publicly available air quality datasets, which provide detailed air quality metrics for various locations across the United States.