How many trees...

One of my refuges here in New York is a thin green slice of park that runs along the island between the river and FDR Drive. Crickets chirp among the rose bushes, and morning glories scramble up the hurricane fence, awake before everyone else. Kids play soccer and baseball, and Chinese men and women do their exercises, facing east. I lie in the grass and look up at the bridge, arching silver against the sky. Across the water, the rusted cooling towers of the Domino Sugar factory glint amber in the sun.

The scene settles in like a photograph: blue sky, aging smokestacks, the geometry of steel. The picture of urbanity, with its layers of progress and decay. The perfect almost-autumn day. But its beauty has a dark side for me now. About four years ago, I developed an intolerance to common toxins. I can no longer ignore the fumes those smokestacks once produced, or the soot that falls from the well-traveled bridge. Chemical sensitivity makes you fear the things you used to love.

At the edge of the park is a construction site. Dumptrucks rumble past, a bulldozer clambers up a pile of earth like a slow, yellow dinosaur. Once, I could watch a building being built for hours. Now, I keep to the other end of the park, fearful that the dust in the air [PM10-- particulate matter less than 10 microns in diameter], will make me achy, dizzy and numb.

http://www.sustainablebuild.co.uk/PollutionFromConstruction.html

Factories were once pure adventure. I would sidestep a surprise blast of combustion, or jump a puddle of unknown oily sludge, admiring the rise of smokestacks and the tangle of pipes, amazed at the fact that these parts came together, Rube Goldberg-like, to create something, anything-- it didn't matter what. Now it matters.

http://www.brownstoner.com/brownstoner/archives/2007/09/toxically_chall.php

I grew up in a city of bridges. To me, they were steel sculptures, silhouetted against mountains or sky. But now, I cannot help consider the traffic that travels them-- and its exhaust.

http://asthmaregionalcouncil.org/about/documents/ComparingToxinsinTobaccoandCarExhaust.pdf

But here in my park, there is green all around me. Isn't it safe here? I have read that trees absorb exhaust, creating more oxygen for us to breathe. There's a barrier, three or four trees thick, between me, my picnic blanket and the highway. At least 25 trees. But is this tiny forest of bark-blasted plane trees enough? How many trees do we need?

After I little research, I learn that 17 trees, over their lifetime, absorb enough greenhouse gasses to balance one year's car exhaust emissions. Two mature trees produce enough oxygen for seven or eight people to breathe. But nearly a million cars enter Manhattan every day. And nearly two million people live here. Can these trees possibly take all that on?

http://www.environmentaldefense.org/documents/6117_AllChokedUp_NYCTrafficandHealthReport.pdf

http://www.oasisnyc.net/resources/street_trees/tree_value/mn.asp

I am afraid the cars are winning.