A species of maple tree offers the best protection from damaging ultraviolet rays of sunlight, a study has suggested. The crimson king (Acer platanoides) variety of maple tree came out as the most protective, closely followed by species of oak and a beech.

Experts say trees can provide people with important protection against the harmful effects of UV radiation. However, not all species of the same group of trees offer the same protection.

Although the crimson king maple was found to offer the most protection, another maple – Acer rubrum (red maple) – provided the least among the trees sampled. 

One of the study’s co-authors, Sivajanani Sivarajah from the University of Toronto, Canada, said that trees provided a lot of benefits, but they were poorly understood. 

“We know trees are essential for air pollutant removal, storm-water reduction, and many other ecosystem services in cities,” she observed. “However, health benefits are not easily quantifiable, like many other indirect ecosystem services. We should be thinking about trees as public health infrastructure.”, she said.

The team found that the crimson king maple, swamp white oak, hackberry, and copper beech trees offered the highest protection factor (PF) (greater than three, meaning its shade allows you to remain outside three times longer than if you had no protection from the sunshine), while the maidenhair tree (ginkgo) and the red maple returned the lowest PF values (less than two).

The trees with crowns that were less transparent and were wider offered greater protection. They also found that it was species with a higher level of shade tolerance that were more effective when it came to UV protection.

“In my opinion,” Dr Sivarajah, “people’s health is more important than beautifying our cities, but it is possible to have both if we plan for it!”