Clothes dryers are an underappreciated source of airborne microfibers

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No one likes when their favorite clothes fall apart. What happens to the pieces of fabric that come off? It's not known how drying affects the environment. A pilot study shows that a single dryer can discharge up to 120 million microfibers annually, more than washing machines.

Microfibers can come from natural fabrics, such as cotton, or synthetic ones, such as polyester. Releasing microfibers into the environment is a concern because they can transport pollutants long distances. The fibers can be a problem if they are swallowed or breathed in. Some microfibers are released from clothes washers into laundry water, but the waste is treated and removed before the water is discharged into rivers or streams. There is no information about whether dryers are an important source of airborne microfibers and microplastics in nature. Kai Zhang, Kenneth Leung, and colleagues wanted to estimate the amount of microfibers released into the air from a household's laundry each year by counting the microfibers generated by cotton and polyester clothing in a dryer.

The researchers dried their clothing in a tumble dryer that had a vent pipe for the outdoors. The machine ran for 15 minutes and they counted the particles that left the vent. The team thinks that the microfibers come from the rubbing of clothes as they tumble around. The dryer released between 1.4 and 40 times more fragments than the washing machines did in previous studies for the same amount of clothing. The release of cotton microfibers is constant regardless of the load size, whereas the release of polyester microfibers increases with more clothes in the dryer. The researchers suggest that cotton microfibers aggregate and cannot stay airborne, a process that doesn't happen forPolyester.

The team estimated that between 90 and 120 million microfibers are produced and released into the air outside by the average Canadian household's dryer every year. To control the release of airborne microfibers, additional filters should be adapted for dryer vents.

Microfibers are released into the air from a household tumble dryer.

Environmental Science & Technology Letters is a journal.

Clothes dryers are an underappreciated source of airborne microfibers.

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