English yew tree
Pollution-trapping yew trees could help clean up Britain’s air, a new study has found. According to scientists from Surrey’s Global Centre for Clean Air Research, the yew’s pointy leaves excelled at trapping toxic particles and releasing them in the rain. Source: Country Living
The team looked at 10 evergreen tree specimens – including viburnum, white cedar, sitka spruce, dwarf pine, Chinese juniper, and Japanese holly – and measured which species caught the most pollution particles, as well as which best allowed the rain to wash those particles to the ground.
Scientists placed the trees in plant pots beside the A3 in Guildford, an area that sees 80,000 cars drive past every day. The yew tree outperformed the other trees by far.
“When tackling air pollution, the ideal leaves cling on to particles when it’s windy but let go of them in the rain,” Yendle Barwise, a former forester and University of Surrey researcher, said in the study.
“That means the wind blows less pollution back into the air but rain can wash it safely to the ground. Being rough and hairy isn’t all it’s cracked up to be. To remove more particle pollutants over time, leaves need to be washed by rainfall, and it seems that the size and shape of the leaf is much more important from this perspective.”
Meanwhile, the study also suggested that ‘pores’ of the leaf could help plants ‘catch’ particles.
Professor Prashant Kumar, founder of the University of Surrey’s Global Centre for Clean Air Research, adds: “We know that planting trees by roadsides can make a big difference to air quality. Our study shows that by choosing your trees carefully, that difference can be even bigger.”
Many planting projects around the UK choose deciduous trees which lose their leaves in winter; however this is when air pollution is often at its worst.
