Reverse graffiti — removing paint or dirt from a wall to create a pattern — is a hot trend internationally, and many cities have had a hard time figuring out how to handle it legally. Inhabitat reader Aislan pointed us to this cool video of graffiti artists removing exhaust on the tunnel walls to write “For a Clean Porto Alegre.” Police show up, hear the invisible inkers make their case, and end up shielding them from traffic while they work!

sustainable design, green art, art, reverse graffiti, transportation, air pollution, air quality

Is reverse graffiti the same as conventional graffiti, since removing the images can be difficult? It ought to depend on whether paint, or just car exhaust, is removed, and whether the reverse writing is potentially offensive. Police in the fast-growing Brazilian city of Porto Alegre seemed to agree when they came upon these reverse taggers at work in a traffic tunnel. Vehicles are the biggest source of air pollution in Porto Alegre, so the message is right on target.