Imagine growing up believing trees are nature’s perfect little oxygen factories, silently working away to purify the air for us—kind of like Earth’s unpaid interns. But then one day, a dude named Andrew, a subscriber of PBS’s Reactions Youtube channel and an employee at an unmentioned city engineering department, crashes your tree-hugging dreams with a question that’s downright SCANDALOUS: “Wait… can trees actually hurt air quality?”
Andrew, trapped in a heated office debate with a coworker who told him the unthinkable, took to Google to verify the information, and he discovered something that made him question everything—like that time we found out Pluto isn’t a planet. Turns out, trees aren’t just mindlessly giving us fresh air—they’re also throwing a little something called isoprene into the mix. And this is where the plot thickens.
The Chemistry of Trees: Friend or Foe?
Yes, trees do release a compound known as isoprene, and it’s not just a few rogue species—roughly a third of all seed-producing plants emit isoprene. The surprise? Isoprene is the second-most emitted volatile organic compound (VOC) after methane, making up a sizable chunk of the emissions we usually associate with industrial pollution.
But what exactly is isoprene, and why is it a concern? Isoprene is a simple molecule composed of carbon and hydrogen, and it’s actually a building block for A LOT of vital substances like vitamin A, rubber, and even testosterone and estrogen! While essential for various biological processes, when released into the air, isoprene undergoes a series of reactions, especially in hot, sunny weather. The problem isn’t isoprene itself—it’s what happens to it in the atmosphere.
Isoprene: A Hidden Polluter?
When isoprene gets released into the air, it reacts with nitrogen oxides (NO and NO₂), typically produced by burning fossil fuels like those from car engines or power plants. The resulting chemical reaction produces ground-level ozone, which, while vital in the upper atmosphere for blocking UV rays, is dangerous when it lingers close to the surface. Ground-level ozone irritates the lungs and can worsen respiratory conditions like asthma, especially in cities during hot weather.
It turns out that on particularly hot days, trees release more isoprene, which means even more potential for ozone formation. So in urban areas, trees can inadvertently worsen air quality, despite their leafy, peaceful appearance.
Are Trees Secret Supervillains?
Before you rush outside to shake your fist at your local oak, let’s slow down. Isoprene isn’t that toxic—more like the tree’s version of a harmless prank. Yes, it’s labeled as “possibly carcinogenic” (at least for lab rats), but the odds of you getting isoprene poisoning from a tree are about as likely as being hit by lightning while simultaneously eaten by a shark. So, you know, not worth packing your bags and moving to the desert just yet.
The problem only arises when tree emissions mix with human-made pollution. So, are trees causing all our air quality problems? Nah. They’re more like accidental accomplices in a heist planned by car exhaust and industrial smoke. In other words, it’s not time to chop down all the trees and start wearing oxygen tanks—just maybe be a little more mindful of all the stuff in the air.
Scientific Citations Aren’t the Whole Story
One key takeaway here is that science, while grounded in fact, is also subject to how you frame the question. Andrew’s coworker wasn’t technically wrong—trees can contribute to air pollution in very specific circumstances—but that doesn’t mean trees are inherently bad for us. As the video below points out, science often finds what it’s looking for. If you search for reasons to blame trees for air quality problems, you’ll find them, just like you’ll find injuries caused by seat belts if you look hard enough. But that doesn’t mean seat belts—or trees—are harmful in a broader sense.
In the end, the real question we should be asking isn’t “Are trees bad?” but rather, “Are trees in cities good or bad for humans overall?” Yes, trees release isoprene, but they also provide shade, help reduce heat, support biodiversity, and yes, they still do absorb carbon dioxide and release oxygen.
So, before you let your coworker’s scientific citations make you rethink your love for nature, remember that trees are just one piece of a much larger environmental puzzle. Rather than cutting them down, maybe we should focus on reducing the other pollutants that turn their emissions into something harmful.
Now you can watch the video. The host, George Zaidan, is not only knowledgeable, he’s also hilarious!
-Video Source: Reactions
-Photo: Public Domain (CC0 1.0 Universal)