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New Study Shows Tree Leaves Can Capture Particulate Matter From Air Pollution

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If you need another reason to plant a tree, consider how it could also help the air quality in your home.  A new study by Lancaster University in the UK found that young silver birch trees can trap particulate pollution from street traffic, and cut particles entering the home by up to 50%.

The team used dust monitoring devices to collect  data on the size and concentration of particles every periodically over five days. Wet wipes were used to gather dust from LED or plasma television screens inside each of the  four houses and then analyzed with magnetic remanence.  The researchers confirmed that the hairy surfaces of the leaves trapped metallic particles that are probably the product of  vehicle emissions and brake dust.

Only one species was tested, and the leaves had a “fuzzy” texture as to maximize particle collection possibility.

Abstract: Exposure to airborne particulate pollution is associated with premature mortality and a range of inflammatory illnesses, linked to toxic components within the particulate matter (PM) assemblage. The effectiveness of trees in reducing urban PM10 concentrations is intensely debated. Modeling studies indicate PM10 reductions from as low as 1% to as high as 60%. Empirical data, especially at the local scale, are rare. Here, we use conventional PM10monitoring along with novel, inexpensive magnetic measurements of television screen swabs to measure changes in PM10 concentrations inside a row of roadside houses, after temporarily installing a curbside line of young birch trees. Independently, the two approaches identify >50% reductions in measured PM levels inside those houses screened by the temporary tree line. Electron microscopy analyses show that leaf-captured PM is concentrated in agglomerations around leaf hairs and within the leaf microtopography. Iron-rich, ultrafine, spherical particles, probably combustion-derived, are abundant, form a particular hazard to health, and likely contribute much of the measured magnetic remanences. Leaf magnetic measurements show that PM capture occurs on both the road-proximal and -distal sides of the trees. The efficacy of roadside trees for mitigation of PM health hazard might be seriously underestimated in some current atmospheric models. – Full Report (must be a member of ACS)

It can’t all be great news. Before you go totally pro-tree,  it should be noted that mass tree planting in urban areas can have a down side when it comes to the environment.  There are some trees that are known to emit isoprene, such as oaks, which t is known to react with smog to create ozone.  Choose your trees wisely.

November 26, 2013 |

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