Just got this via Twitter (thank you Romain Colin):

i think this is a neat idea, a sort of ecological graffiti…

“An experimentation full with freshness by the illustrator Anna Garforth. The idea: ecological graffiti, i.e. surfant on the tendency green, which makes its appearance in urban environment. A calligraphic work at the same time original and full with direction.”, sais Jeremie on FUBIZ – one of my favourite websites