“Nature’s voice is written in dirt like it would be in blood,” states original reverse graffiti artist Moose (Paul Curtis), in the video of the Reverse Graffiti Project, powered by Green Works, which highlights his work in San Francisco’s Broadway tunnel. Reverse graffiti involves creating artwork using cleaning materials to remove signs of pollution, rather than using paint. The result, also judging from the images on this list of the 35 greatest works of reverse graffiti, is stunning. I also really appreciated Brazilian artist Alexandre Orion’s work of adorning a tunnel in Sao Paolo with skulls to remind drivers of the impact of a car’s emissions on the planet.

Check it out: