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APRIL 2012
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HEMISPHERESMAGAZINE.COM
THE SOLUTION:
PLANT UPWARD.
THE PROBLEM: AS
CITIES GROW, THE
SMOG THICKENS.
THE SOLUTION:
MAKE
BUILDINGS THAT CLEAN
THE AIR.
Researchers have long known
that one of the primary clean-
ers in the atmosphere
is an ephemeral
particle known
as a hydroxyl
radical. Until
recently,
waiting for
this particle to
slowly clear out
smog and pollut-
ants was one of the
only ways to get clearer
air. In the past few years,
however, scientists have fig-
ured out how to make extra
hydroxyl radicals by le ing a
common mineral known as
titanium dioxide react with
nothing more than moisture
and sunlight. As a result, two
eco-friendly companies have
started including it in build-
ing materials: Aluminum
producer Alcoa has coated
its popular Reynobond With
EcoClean panels with enough
titanium dioxide so that just
10,000 square feet cleans as
much air as 80 trees, while
an LEED-certified company
called Pureti has developed
a liquid coating that can be
used on everything from
decking to public buses.
Because these materials don’t
reduce CO₂, they’re not quite
as effective at cleaning air as
trees are, but they sure beat
standing around waiting.
—JACQUELINE DETWILER
THE PROBLEM
SPRAWL KILLS TREES.
In the center of Milan, construc-
tion is well under way on the
$87.5 million Bosco Verticale, an
ambitious two-building apart-
ment complex that will double as
the world’s first vertical forest.
Every unit will have a concrete
balcony planted with humidity-
creating and CO 2 -filtering trees,
shrubs and flowers that will get
their nourishment from recycled
gray water. The buildings them-
selves—the taller of which tops
out at 27 stories—will rely on the
sun for much of their power.
The best part? This burst
of green on Milan’s skyline comes
cheap. Project architect Stefano
Boeri has said these forest
features will increase the build-
ings’ construction costs by only 5
percent, making the whole thing
not only energy-efficient, but
cost-effective as well. This should
have the complex’s future inhabit-
ants breathing easier, but they
probably won’t be the only ones:
The city’s winged residents will
surely know a good thing when
they see it, too.
—SAM POLCER
CITIES