Boris beds in

Major tree-planting under way in capital as new research points to health benefits

Fresh from his victory in the London mayoral elections, Boris Johnson has announced a scheme to plant 10,000 new trees on the streets of the capital over the next three years. Funded by the Greater London Authority, charities such as Trees for Cities are to draw up a list of the 40 areas they believe would benefit most. Londoners will then be able to vote (via the GLA website) on the order the areas receive their trees.

The announcement comes shortly after publication of a Columbia University report showing that tree-lined streets cut levels of asthma in urban areas – particularly among young children. Conducted in New York, the study found that for every additional 343 trees per square kilometre, asthma rates fell 25% among children aged between four and five, even after taking account of factors such as relative affluence and local sources of pollution.

It remains unclear how much of that is directly attributable to trees cleaning the air of pollutants. For Graham Simmonds, chief executive of Trees for Cities, that’s only the start. “Research has shown,” he says, “that trees help to alleviate respiratory problems by trapping airborne particulates more common to towns and cities – the debate is really on the extent. But it’s clear that people are also much keener to get out and exercise more in greener urban
environments.”
 
That’s good for adults, and even better perhaps for those in their formative years when exposure to microbes builds an immune system more capable of fighting infection and allergies. With 1 in 10 children in the UK currently receiving treatment for asthma, perhaps in future years we’ll see local health authorities leading investment in tree-lined streets. – Jon Wallace

24 June 2008

Jon Wallace