Our modern metropoli have accumulated a lot of dirt and grime from pollution and traffic. Street artists took note and started cleaning images and messages into the grime using cleaning supplies and high powered water sprayers with stencils (below).

[ Image from Reverse Grafitti Project ]

[ Image from Inhabitat ]

The messages can last up to six months before more grime fills in the cleaned areas. Some entrepreneur minded individuals realized that this could become a legitimate advertising method for edgier companies.

So now there are the services of Green Grafitti from the Netherlands and the UK based Street Advertising Services that will spray your message or logo into the dirty streets of your city.

Street  Advertising Services

Green Grafitti

They say it costs a fraction of traditional outdoor advertising, and hey, your cleaning up the world one ad at a time.

[ via - Springwise ]