A detailed data viz pinpoints dirty power plants, too.

(Hsu et al/Yale)View full-screen map

If you’ve ever wondered how air quality in your neighborhood compares to the dirtiest cities in the world, this map is for you.

A team of Yale University environmental researchers just released a map tool that shows concentrations of fine particulate matter (PM 2.5) across the whole world in pretty astounding detail: each pixel represents a 10-by-10 kilometer square. They also included visual representations of the world’s dirtiest power plants—a timely feature as the U.S. announces a sweeping new plan to reduce carbon emissions from power plants, especially coal-fired ones.

PM 2.5 inflicts critical damage on populations exposed to it in high concentrations, says map co-creator Alisa Zomer, manager of the Yale Environmental Performance Index. "PM 2.5 is invisible to the human eye,” she says. “But it penetrates into blood and organ tissues, and can lead to cardiovascular and respiratory diseases."

The map draws from satellite measurements to calculate average particulate matter. Users can also toggle on citywide PM 2.5 counts, which come from the WHO’s ambient (outdoor) air pollution in cities database from 2014. Power plants came from the database over at Carbon Monitoring for Action. The air pollution data represent averages, so Zomer notes that the best way to track particulate matter is to install more local sensors in at-risk neighborhoods. That can inform policies and political action to clean up the air.

A detail from the map shows air pollution and dirty power plants clustered around the dense East Coast. (Hsu & Wong/Yale)

The new map marks a significant improvement on the one published last year by Zomer and Angel Hsu, director of the Environmental Performance Measurement Program at Yale. The original map simply colored each nation based on its average PM 2.5 readings. The new map, when you click “Show Satellite Data,” illustrates just how much that pollution can vary within a country. (Yale undergraduate David Wong helped with programming for the updated version.)

For instance, the expanse of land between the East Coast and the Missouri River appears red as an extremely rare steak, indicating higher concentrations of pollutants, whereas points out West fade to yellow. CityLab’s neighborhood in Washington, D.C., has a reading of 14 micrograms per cubic meter. That exceeds the World Health Organization’s standard of 10 for safe air, landing in the lower range of “moderate” health concern. In general, densely populated areas with lots of cars and high energy demand are host to higher PM 2.5 concentrations and more of the dirtiest power plants.

That pattern holds true around the world. For all the headlines about how bad the air is in Beijing or New Delhi—and their regions do stand out on the map—Europe, Japan, Korea, and the U.S. have their work cut out for them, too. The Obama administration’s new power plan could help get America on track; though it targets carbon dioxide rather than particulate matter, both emissions come from dirty coal plants.

"On most urban environment issues, like water and sanitation, the U.S. and the developed world tend to do really well,” Zomer says. “But air pollution is still problematic in developed countries.”

This post has been updated to note undergraduate David Wong's contribution to the new map.

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