Authors of a study conducted at Hawai’i University recently reported another good reason to redouble global efforts to beat plastic pollution: as plastics decay, they emit traces of methane and ethylene, two powerful greenhouse gases, and the rate of emission increases with time. The emissions occur when plastic materials are exposed to ambient solar radiation, whether in water or in the air, but in air, emission rates are much higher.
The researchers tested polycarbonate, acrylic, polypropylene, polyethylene terephthalate, polystyrene, high-density polyethylene and low-density polyethylene – materials used to make food storage, textiles, construction materials and various plastic goods.
“Low-density polyethylene emits these gases when incubated in air at rates about 2 times and 76 times higher than when incubated in water for methane and ethylene, respectively,” says the study.
“Our results show that plastics represent a heretofore unrecognized source of climate-relevant trace gases that are expected to increase as more plastic is produced and accumulated in the environment,” the study concludes.
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