Guildford: Surrey university says small leaves best for pollution

The effective awl-shaped leaves were found on Japanese Cedar and Lawson's Cypress

Evergreen trees with smaller leaves are the best for stripping pollution from the air, a study says.

The University of Surrey's research focused on ten trees on a stretch of the A3 in Guildford and tested which caught the most pollution particles.

The university's Global Centre for Clean Air Research (GCARE) also looked at which best allowed the rain to wash those particles safely to the ground.

Ideal leaves cling to particles when it's windy and let go in the rain.

Former forester and University of Surrey researcher Yendle Barwise said: "It seems that the size and shape of the leaf is much more important from this perspective."

An estimated 80,000 vehicles drive along the stretch of road every day

The university said many planting projects use trees which lose their leaves in the winter - even though that is when air pollution is worst in towns and cities.

For that reason, scientists chose ten evergreen specimens and placed them in plant pots beside the A3 in Guildford.

Of those studied, Yew (taxus baccata) was the plant which removed the most air pollution, and the most effective leaf types were awl-shaped.

For the Yew, more pollution particles gathered on the porous underside of the leaf despite the other side being 47% rougher.

GCARE founder Professor Prashant Kumar said: "We've shown that smarter choice of plants can take even more pollution out of the air."

"Other factors, like the tree's height, leaf chemistry, or how many trees you plant, could also make a big difference," he added.

Follow BBC South East on Facebook, on X, and on Instagram. Send your story ideas to [e-mail].