Page last updated at 00:18 GMT, Thursday, 1 May 2008 01:18 UK

Tree-lined streets 'cut asthma'

Trees in New York
New York is currently planting more trees




The study appears in the Journal of Epidemiology and Community Health.




This is a positive first step into a new area of research linking the environment and asthma
Leanne Male
Asthma UK



Exposure theory

Some experts believe that children who are exposed to few microbes in early life are at an increased risk of asthma because their immune systems do not get the practice they need at fighting infection.

Therefore, if a tree-lined street encourages outside play, it might help reduce the risk of asthma by maximising the odds that children will be exposed to microbes.

However, trees are also a source of pollen, which may potentially exacerbate asthma symptoms in vulnerable children.

Lead researcher Dr Gina Lovasi admitted the effect, if any, of trees was far from clear.

She said: "There may be something else healthful about the areas that had more trees.

"For example, trees could be more abundant in areas that are well maintained in other ways."

Leanne Male, assistant director of research at the charity Asthma UK, said: "Previous research looking at the influence of the environment on levels of asthma has focused on negative aspects, such as pollution and chemical exposure.

"This innovative report is the first to look specifically at the potentially beneficial effects of trees in urban areas and raises some interesting issues.

"However, there are a number of other factors that have not been considered, for example whether the families involved have pets.

"Despite the need for further work, this is a positive first step into a new area of research linking the environment and asthma."

New York City is planning to plant 1 million extra trees by 2017.

08 Jan 04 |  Medical notes

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