Small and smooth – not rough and hairy – best for removing pollution, finds University of Surrey study

If you're trying to take pollution out of the air, choose evergreen trees with smaller leaves. That's according to a new study from the University of Surrey.   
Researchers from Surrey's Global Centre for Clean Air Research (GCARE) tested ten trees beside a busy main road. They studied which caught the most particles of pollution and which best allowed the rain to wash those particles safely to the ground.  
It had been thought that leaves with rougher surfaces and minute hairs would catch more pollutants. Yet that wasn't borne out by the evidence.