Plane tree felling: the hidden risk to health

We already know that cutting down healthy trees makes air pollution worse. But that’s not just because they absorb pollutants. Yesterday I learnt that plane trees have spiky “hairs” (called trichomes) on their leaves which can exacerbate the symptoms of lung conditions, especially when disturbed by pruning or felling.

Ian Dalton, a professional tree officer for a London borough, posted in the Facebook group for Sheffield Tree Action Groups (STAG):

Plane trees have a layer of fibrous "dust" on the leaves which, when viewed under a microscope have tiny hooks that get caught in your windpipe and can cause severe coughing...

If a plane tree is pruned when it’s in leaf, this will spread the dust and exacerbate problems like asthma and bronchitis as well as hayfever. This is why most London boroughs plan their pruning schedules so that plane trees are only pruned during the winter.

Unfortunately, many people are posting in the STAG Facebook group to report that Sheffield council contractor Amey seems to be felling plane trees now, in the middle of summer. The felling crews bring wood-chippers which blow the dust around and make the problem even worse.

Mr Dalton went on to say that any Sheffield residents who see Amey working on plane trees during the summer should complain to Streets Ahead (the highways maintenance collaboration between Sheffield City Council and Amey) because pruning or felling at this time of year is a health risk to the public and shouldn't be continuing until the trees have lost their leaves.

Research from Australia suggests that plane tree trichomes are more of a respiratory irritant than normal plane tree pollen, and that the trichome season is longer. (If you read the linked paper, it’s worth remembering that June is the start of winter in Australia!)  That’s not an argument for getting rid of plane trees in urban spaces, because it must be weighed against all their great qualities, such as their ability to absorb air pollution and thrive in dusty city settings. But it is an argument to leave them well alone until the leafing season is over.