Clothes dryers are an underappreciated source of airborne microfibers


Date:
January 12, 2022
Source:
American Chemical Society
Summary:
No one likes when their favorite clothes develop holes or unravel
after many laundry cycles. But what happens to the fragments
of fabric and stitching that come off? Although it's known that
washing clothes releases microfibers into wastewater, it's unclear
how drying impacts the environment. Now, a pilot study reports
that a single dryer could discharge up to 120 million microfibers
annually -- considerably more than from washing machines.



FULL STORY ==========================================================================
No one likes when their favorite clothes develop holes or unravel
after many laundry cycles. But what happens to the fragments of fabric
and stitching that come off? Although it's known that washing clothes
releases microfibers into wastewater, it's unclear how drying impacts the environment. Now, a pilot study in ACS' Environmental Science & Technology Letters reports that a single dryer could discharge up to 120 million microfibers annually -- considerably more than from washing machines.


========================================================================== Microfibers can come from natural fabrics, such as cotton, or
synthetic ones, such as polyester -- which are also considered to be microplastics. Releasing microfibers into the environment is a concern
because they can adsorb and transport pollutants long distances. And
the fibers themselves can be irritants if they are ingested or
inhaled. Previous studies have shown that microfibers are released
from clothes washers into laundry water, but this waste is treated,
removing some or most of the fibers before the water is discharged
into rivers or streams. However, there's very little information about
whether dryers, whose air passes through a duct and is vented directly
to the outdoors, are an important source of airborne microfibers and microplastic contamination in nature. So, Kai Zhang, Kenneth Leung,
and colleagues wanted to count the microfibers generated by cotton and polyester clothing in a dryer to estimate the amount released into the
outdoor air from a household's laundry each year.

The researchers separately dried clothing items made of polyester and
those made of cotton in a tumble dryer that had a vent pipe to the
outdoors. As the machine ran for 15 minutes, they collected and counted
the airborne particles that exited the vent. The results showed that
both types of clothing produced microfibers, which the team suggests
comes from the friction of clothes rubbing together as they tumbled
around. For both fabrics, the dryer released between 1.4 and 40 times
more microscopic fragments than were generated by washing machines in
previous studies for the same amount of clothing. They also found that the release of polyester microfibers increases with more clothes in the dryer, whereas the release of cotton microfibers remains constant regardless of
the load size. The researchers suggest this occurs because some cotton microfibers aggregate and cannot stay airborne, a process that doesn't
happen for polyester. Finally, the team estimated that between 90 and
120 million microfibers are produced and released into the air outside
by the average single Canadian household's dryer every year. To control
the release of these airborne microfibers, additional filtration systems
should be adapted for dryer vents, the researchers say.

The authors acknowledge funding from the State Key Laboratory of Marine Pollution; the Innovation and Technology Commission of the Hong Kong
Special Administrative Region of the People's Republic of China; a
Discovery Grant from the Natural Science and Engineering Research Council
of Canada; Western Economic Diversification Canada; the Canada Foundation
for Infrastructure; the Canada Research Chair program of the Natural
Science and Engineering Council of Canada; and one of the authors was
supported by a Distinguished Visiting Professorship at Baylor University.

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========================================================================== Journal Reference:
1. Danyang Tao, Kai Zhang*, Shaopeng Xu, Huiju Lin, Yuan Liu, Jingliang
Kang, Tszewai Yim, John P. Giesy, and Kenneth
M. Y. Leung. Microfibers Released into the Air from a Household
Tumble Dryer. Environmental Science & Technology Letters, 2022 DOI:
10.1021/acs.estlett.1c00911 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220112093953.htm
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