Can trees take particles out of the air? They probably do a bit, but trees really aren’t made to take particles out of the air. If they do, they probably do so when they suck in air and water through their roots. While they’re sucking in, some particles may get filtered out, but it’s probably not much.<\/p>\n
When Are Trees Active?<\/h3>\n
There’s another problem: during the winter, trees are less active, so they’d be even less effective. This comes at the worst time possible, because China’s air pollution is worse during the winter.<\/p>\n
![\"Summer](\"\/wordpress\/wp-content\/uploads\/2019\/08\/Summer-winter-trees-active.jpg\")
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2. Giving Particles A Place to Land<\/h2>\n
Research reports that I\u2019ve read focus on how trees give particles a place to settle or impact on, rather than sucking up particles. For example, researchers at the USDA Forest Service explain<\/a>: \u201cmost particles that are intercepted are retained on the plant surface.\u201d<\/p>\n How big is that effect? I don\u2019t think anyone knows of a way to measure this directly, but\u00a0researchers have estimated that all of the tree cover in London reduces larger PM10 particles by 0.7\u20131.4%<\/a>. Other researchers estimated that\u00a0more than doubling the tree cover in Glasgow would reduce PM10 levels by about 2%.<\/a>\u00a0Across 10 US cities, the\u00a0highest<\/b>\u00a0estimate was that\u00a0tree cover reduces the smaller PM2.5 particles by 0.24%<\/a>.<\/p>\n At that rate, how much more tree cover would we need to reduce PM2.5 by 50%? Let\u2019s start with the highest PM2.5 effect estimate of 0.24%. At that rate, we\u2019d need to multiply tree cover by 208 times! Maybe we could plant trees on top of trees?<\/p>\n Don\u2019t get me wrong. I love trees, and I would love it if cities had more trees. But they won\u2019t be solving our air pollution problems any time soon.<\/p>\n In fairness, governments have planted trees for reasons other than sucking up particles. Another goal is to block sandstorms originating in Mongolia from making it all the way to Beijing. In this case, trees are probably somewhat effective. However, sandstorms really aren’t what most people are concerned about in China.<\/p>\n From a big-picture perspective, it makes the most sense to cut down on pollution at the source. It’s a heck of a lot cheaper to (1) put emissions control technology on smokestacks and (2) remove old polluting cars that lack\u00a0catalytic converters<\/a>\u00a0than it is to try to suck up all those particles after they’re already in the air. So if I were in charge of solving the world’s particulate problem, I’d start at the source rather than go planting trees.<\/p>","protected":false},"excerpt":{"rendered":" Planting trees to solve China’s air pollution would be a very ineffective way. Let me break down the effect of trees into (1) sucking up particulate and (2) giving particles a place to land. 1. How Much Particulate Air Pollution Do Trees Suck Up? Let’s talk about the most commonly … <\/p>\n3. A third use: Blocking sandstorms<\/h2>\n
What Would Work Better than Planting Trees to Solve China’s Air Pollution Problem<\/h2>\n