Clothes dryers apparently emit masses of microplastics

Household clothes dryers are an overlooked problem for the environment, writes a team led by Kai Zhang and Kenneth Leung of City University Hong Kong after experimenting with the devices. The group found that dryers release 1.5 to 40 times as many microscopic particles from clothes during operation as a washing machine. And unlike the latter, whose wastewater is cleaned of particles at a sewage treatment plant, the microfibers from the dryer enter the environment unfiltered.

That's what Zhang, Leung and their team write in the journal Environmental Science & Technology Letters. They tested a commercial dryer with laundry items made of cotton and polyester. In both cases, microfibers were released. However, the problem is more serious with polyester fabrics: on the one hand, the output increases the more laundry is put into the drum, and on the other hand, polyester is a plastic, so the microfibers are to be regarded as microplastics. Unlike cotton, they do not break down in nature. Instead, they can accumulate in the food chain, for example. Environmental toxins also concentrate on microplastic particles. They are now ubiquitous in ecosystems, but also in the home.

The group attributes the difference between cotton and polyester to the fact that cotton fibers clump together and sink down, while polyester fibers float. All told, the study's authors estimate that between 90 and 120 million microscopic fibers are released into the surrounding air each year when a dryer is operated regularly.

In their tests, the group used a dryer that exhausts to the outdoors via a hose. The exhaust air was sucked in place and then analyzed in the lab. In their opinion, a special filter system should be used at this point in the future, which could reduce the input of microfibers. In the long term, however, materials such as polyester should be replaced by more environmentally friendly alternatives. To what extent the results of their tests can be applied to condensation dryers, which dehumidify the exhaust air by means of condensation and do not discharge it directly to the outside, is not clear from the study.

Spectrum of Science

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