When it comes to fighting air pollution and alleviating the impact of global warming, trees are superheroes. They absorb carbon dioxide and air pollutants, lower temperatures with their shade, and add oxygen to the air we breathe.
According to American Forests, trees clean our atmosphere…
“… by intercepting airborne particles, and by absorbing ground-level ozone, carbon monoxide, sulfur dioxide, and other greenhouse gases. A single tree can absorb 10 pounds of air pollutants a year, and produce nearly 260 pounds of oxygen- enough to support two people.”
Not only that, the older and bigger a tree is, the greater its capacity to lock up carbon. A recent study, based on decades of measurements from hundreds of trees all over the world, found that as trees get bigger, their growth rate keeps increasing. So not only do senior trees prevent large amounts of carbon from escaping into the atmosphere and contributing to climate change, they strengthen that superpower every year by adding more mass to their trunks, branches, and leaves.
In an interview with the Los Angeles Times, the study’s leader, Nate Stephenson, a California-based research ecologist with the U.S. Geological Survey, put it this way,
“It’s the equivalent of managing a sports team. You need to know who your star players are. It turns out they’re not the 20-year-olds. They’re the 90-year-olds.”
While senior trees may be the star players, we still need the rookies who will eventually replace them. And because trees are such effective anti-pollution devices, some cities are planting them in less foliated neighborhoods to help meet air quality goals, and reduce asthma among their residents.
In Sacramento, California, for example, trees are being considered as one tool to help the city meet air quality goals under the Clean Air Act regulations. A preliminary study by the Center for Urban Forest Research, the Sacramento Tree Foundation, and the Sacramento Metropolitan Air Quality Management District has, among other things, developed a tree-planting plan for inclusion in the State Implementation Plan.
According to a document on the U.S. Forest Service website,
“The new trees won’t be just cleaning the air. They will also be providing the residents of Sacramento and the surrounding area with numerous benefits: less spending for energy, reduced atmospheric carbon dioxide levels, cleaner stormwater, increased property values, improved physical and mental health, a greater sense of place, and a more beautiful environment.”
Sacramento’s neighbor to the north, Portland, Oregon, is also using trees to improve the health and quality of life for its residents. In this case, trees are being deployed to ease the city’s asthma problem.
An article in the Portland Tribune, notes that new maps created by the Coalition for a Livable Future can pinpoint neighborhoods with high rates of asthma. Not surprisingly, based on past research, these are low-income areas with many people of color. The article adds,
“They also reveal higher rates along freeways and highways, which tend to have relatively few trees.”
To help counteract the impact of pollutants on residents’ health, Friends of Trees plants trees in low-income neighborhoods with subpar tree canopy and high levels of air pollution. Over the past four years, the group has planted 60,000 trees along Interstate 205 in East Portland, and it recently put in close to 90 trees on the grounds of an elementary school in a low-income neighborhood — also sited near that highway — that had a low tree canopy.
Scientists in Portland also found that a tree’s health-protecting superpowers extend to newborns as well. According to the article, “The more trees located within 50 meters of a home, the less likely a baby from that household would be born underweight.”
Trees may be superheroes in the fight for clean air, but they can’t do it alone, we need strong regulations too.