Trees

Vegetation Filters Harmful Particulates from Air

Barbara Maher, an environmental researcher at the University of Lancaster in the UK, ran a study at four primary schools set along busy streets in nearby Manchester, set up expensive air quality monitoring equipment. They installed the plants, she calls tredges, a combination of trees and hedges—as a tool to combat a public health emergency: particulate matter pollution, which studies have tied to premature death, mainly via its effects on the heart, lungs, and vascular system. In her own research, Maher has found the pollutants embedded deep in human tissues. She and others have found that leaves pick up and store particulates from the air. And when she and colleagues lugged potted silver birch trees to the edge of a busy road near their campus in Lancaster, they saw levels of particulate pollution inside the houses just behind the trees drop by more than 50 percent. While they’re no substitute for reducing emissions themselves, Maher says, tredges could be “an interim measure that can actually make a measurable difference almost straight away.”

Smells of Nature Lower Physiological Stress

Tall trees with thick, lush canopies,with slight breeze blowing, birds are singing, and there’s a faint smell of forest—mostly fir trees and mushrooms. For a moment, people experiencing the scene may forget they’re in a research lab in Sweden helping scientists run an experiment to test how the natural environment affect physiological stress. There’s a consensus among researchers that being in nature contributes to good physical and mental health, says Marcus Hedblom, an ecologist at the Swedish University of Agricultural Sciences who helped run the virtual reality experiment. Research has shown that viewing natural scenes can lower heart rate and restore focus, both of which are important for combatting physical and mental health disorders. Previous studies found that listening to clips of multiple bird species singing in an urban area had a stronger positive effect on people’s perception of the space. Hedblom and his colleagues hypothesized that an environment with rich biodiversity would reduce stress faster.