20 SPRING 2015 n ARBOR AGE www.arborage.com
INDUSTRY INSIGHTS
In 2012 I attended an urban forestry conference in Sacramento.
I found one presentation highly provocative because it hinted at
a potential downside of the urban forest. What could possibly be
negative about living in close
proximity to tree canopy?
One of the many benefi ts
of urban tree canopy is said
to be reduced air pollution,
which could be expected to
lead to a healthier respiratory
environment. But Assistant
Professor in Epidemiology at
Columbia University Mailman
School of Public Health, Dr. Gina
Lovasi, and her 11 coauthors
found a surprising result for
members of a group of 549 New
York City children.
A statistically significant
subset of those children —
those whose mothers lived
n BY MICHELLE SUTTON
near urban tree canopy while pregnant — developed allergic
sensitization to tree pollen by age seven. In their analysis
of the findings, Lovasi et al identified pollen as a potential
factor, but they didn't have enough information to firmly lay
the blame there.
However, other studies are more specific to pollen. For
example, "The Association of Tree
Pollen Concentration Peaks and
Allergy Medication Sales in New
York City: 2003–2008" by Sheffield
et al found that maple, oak, and birch
tree pollen concentration peaks
were followed by large, statistically
significant increases in over-the-
counter allergy medication sales.
According to the American
Academy of Allergy, Asthma and
Immunology, more than 35 million
Americans suffer from seasonal
allergies, including to tree pollen.
The pollen question is likely
to become more visible as laws
prohibiting the planting of the most
allergenic trees are being enacted
Before looking through his microscope, Tom Ogren placed a
small piece of window screen over a glass slide with pollen
from a male tree. This shows why window screens are next
to no protection against pollen from nearby trees.
PHOTO
BY
TOM
OGREN
Dealing with Allergenic Trees
Pollen, We Have a Problem
What possible downside could the
urban forest present? Most urban
forests are heavy in male cultivars,
and the resulting pollen shed from
certain highly allergenic tree species
can create a public health hazard.
PHOTO
BY
MICHELLE
SUTTON
