Air pollution is one of the most pressing problems we face; it damages our health and our planet. Among the worst offenders are Nitrogen Dioxide, pumped out by boilers and engines, and particulate matter, created by vehicle exhausts and log fires.

Put that way, air pollution sounds far removed from a landscape architect’s scope – a national problem ripe for politicians to solve. But while policy is needed for the bigger picture, there is a role for our profession to play.

Research tells us that some plants are better than others when it comes to filtering air – an area Chris Churchman has been exploring in collaboration with the Birmingham Institute of Forest Research (BIFoR). Together they have been creating planting strategies featuring a selection of species chosen for the positive impact they can have on air quality.

Some of the best plants for filtering air feature hairy or waxy leaves – perfect for trapping pollution. That makes Birch a bit of superstar, along with some species of pine. Surprisingly, other species aren’t quite so good – some trees are themselves polluters, emitting Volatile Organic Compounds (VOCs) which can interact with Nitrogen Oxide (NOx) to produce Ozone. Oaks fall into this category, so under certain circumstances they can exacerbate pollution levels rather than bringing them down.

It’s a rich area of research with the potential to bear nationwide benefits. The BIFoR group have already advised HS2 on planting, particularly at Interchange Station, a site hit by pollution from the road (M42) and the skies (Birmingham airport).