Manchester is looking at lessons from a recent study about planting 'tredges' between roads and school playgrounds. The trees managed as a head-high hedge were installed at three Manchester primary schools in the summer of 2019—one with ivy; one with western red cedar; and one with mixed western red cedar, Swedish birch and an inner juniper hedge. A fourth school, with no planting, was a control. Western red cedar brought the biggest overall reductions in particulate matter and black carbon. Its prolific, small, rough, evergreen leaves capture and stop particulates from circulating. Rain then washes them off so  leaves can capture more. Carefully selected and managed tredges could be used elsewhere in urban areas to cut the health impacts of traffic pollution, the researchers said. Manchester City Council will consider how to use the lessons to make further targeted use of green infrastructure in the UK city.

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