By Rachael Lallensack

On a trip to India in 2012, Anirudh Sharma captured a photo of a diesel generator blowing black soot against a white wall. That dark, triangular stain made Sharma, who was then a student at Massachusetts Institute of Technology’s Media Lab, think seriously about pollution—and also about pigments, like ink.

The black ink we use in our pens or in inkjet printers is essentially made from soot. The technical term for the substance is “carbon black,” and it is the powder that remains after burning coal or oil. The powder is mixed with a polymer and a solvent to turn it into smooth, flowing black rollerball ink.

“So, if you can do it with soot, can we do the same with air pollution?” Sharma explains. “The black color in the pen you use is made by burning fossil fuels to make ink. But you shouldn’t need to burn new fossil fuels just to make ink. Fossil fuels are already being burned.”

If he could find a way, he thought, to capture the particles that produced that stain on the wall in his photograph, he could not only reduce the amount of pollution released into the air, but also turn it into something new, or perhaps something beautiful.