We’re barking up the wrong trees.
A new study reveals that a majority of the 7 million trees in New York City are emitting “volatile compounds” that do more harm than good for our air quality — especially during scorching heat.
“We’re all for planting more trees. They bring so many good things,” said study coauthor Róisín Commane, an atmospheric chemist at Columbia University’s Lamont-Doherty Earth Observatory. “But if we’re not careful, we could make air quality worse.”
The arbors in question include oaks and sweetgums which produce high volumes of a chemical composition called isoprenes — and they’re rooted in the Big Apple more than any other species.
“There is no reason to think that trees don’t play a role in what’s in the air,” said lead author Dandan Wei, of the local Columbia Climate School. “We just didn’t have the tools before this to understand this particular aspect.”
When that compound interacts with nitrogen oxide pollution, which is emitted from cars and building exhaust, the result is a key driver for respiratory illnesses.
Asthma and chronic bronchitis were listed as the most vulnerable conditions, according to the new report in Environmental Science & Technology.
And, if NYC continues its usual planting of those style trees, isoprene levels in Manhattan will surge about 140% with a 30% boost in ozone.
In the more lush borough of Queens, both isoprene and ozone are expected to quadruple, researchers note.
Oak trees, which already let out 800 times more isoprene than maples, emit in especially high volume when the city reaches boiling temperatures in the high 90s as well. They make up 37% of city trees while the sweetgums consist of 17%.
After analyzing satellite imagery that combined with Parks Department data, the research team found that local trees played a role in ozone creation during hot days.
But they maintain it’s not empirically the trees to blame — but instead what their organic emissions are mixing into.
“If we lowered [nitrogen oxides] significantly, trees wouldn’t be a problem,” said Wei. “We don’t want to convey the idea that trees pollute the air. It’s the cars.”
Although researchers note the city is making some headway in reducing nitrogen oxides from exhaust and man-made pollutants, it would take up to 80 years to see some real improvement.
“No quick fix appears to be imminent,” a release on the news read.
