Research out of the Massachusetts Institute of Technology is a reminder that running isn't necessarily as ecofriendly a sport as we might think it is.
Published in the Journal of Cleaner Production, the research says that the typical pair of running shoes generates 30 pounds of carbon dioxide emissions, a carbon footprint equivalent to keeping a 100-watt lightbulb on for one week.
Credit: Runner's World
That might not sound like a huge amount of carbon dioxide emissions, but it becomes significant when you consider that, according to the study, about 25 billion of running shoes are sold worldwide every year.
More than two-thirds (68%) of the emissions produced by running shoes stem from the manufacturing process. Materials account for another 29%.
"For consumer products not requiring electricity during use, the intensity of emissions in the manufacturing phase is atypical," the study notes. "[M]ost commonly, materials make up the biggest percentage of impact."
The large contribution of manufacturing is because of the complex nature of assembling the typical running shoe. "A single shoe can contain 65 discrete parts that require 360 processing steps for assembly," the study reports.
In a press release accompanying the study, the researchers say that revised manufacturing processes, such as printing directly on a shoe instead of attaching separate pieces, could lower running shoes' carbon footprint. In that regard, some shoe companies are ahead of the researchers, as companies like Nike, New Balance and Adidas, among others, experiment with 3D printing, welding instead of stitching, and other innovative processes that produce shoes in fewer steps.
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