Art less pollution: cleaning is not a crime

"This is what you may call reverse graffiti. Brazilian streetartist Alexandre Orion removes soot to draw skulls and create ‘Art less pollution’.
At dawn on July 13, 2006, Brazilian streetartist Alexandre Orion started working on a intervention in the Max Feffer tunnel Sao Paulo and created ‘Art less pollution’. The intervention was through a process of substraction, scraping off layers of soot from vehicle exhaust built up on tunnel walls to produce images of human skulls.
Read more about the intervention and see pictures at Alexandre Orion’s website."

Via Osocio.