supports media playback device

Poster "absorbed 20 cars worth of pollution" in Sheffield

May 19 2014 Last updated at 13:31 BST clock

A huge sign was founded in Sheffield in order to eliminate air pollution.

The researchers say that the flag removes harmful nitrogen oxide in the air, absorb the pollution of about 20 vehicles per day.

Pro-Vice-Chancellor for Science at the University of Sheffield, Professor Tony Ryan, told BBC Radio 5 Live Breakfast your idea.