Asthma and trees, Cause & effect?


Published: 14/05/2012

by Andrew McKernan


Research on the incidence of Asthma and the presence of street trees found the opposite results to what many people believe.

A New York study found that Asthma rates have increased by 50% from 1980 to 2000, while tree populations were decreasing. An inverse effect of what would be expected if trees were the root cause of asthma.

Further investigation found that areas with a greater density of street tree cover had a lower prevalence of early childhood asthma.

An increase of 343trees/km were associated with a 29% lower early childhood prevalence of Asthma.

A large scale Natural experiment is now underway in New York. They are going to plant one million trees by 2017. They have already planted over 500 000! Researchers are going to monitor the relationship to Asthma as the program progresses.

Research was conducted by the National Institute for Environmental Health Science (R01-ES014229) and summary findings were published in The Bark for Arboriculture Australia, Vol13,No2 2011.

Further information on the million tree program is at...