For a story about air quality in South Korea, NPR asked me to create three D3 graphics comparing Seoul with comparably sized metro areas in China (Beijing and Shanghai) and the United States (Los Angeles and New York City).
The process involved obtaining and analyzing reams of hourly PM2.5 readings for each location over several years, and then scaling those concentrations into the digestible health ratings categories developed by the U.S. Environmental Protection Agency.
I then spent time sketching and summarizing with the data before settling on our graphics. It was great to work with my friends again at NPR — and to tinker with its Visuals team’s daily graphics rig.
First, a look at a year of Seoul’s PM 2.5. You can see the minimum and maximum readings each day and the daily average line. Some days are quite bad:
Not as bad as China, of course:
But worse than New York City: