No one wants their favorite clothes to develop holes or unravel after many laundry cycles.
But what happens to the fabric and stitching fragments that fall off? Although it is well known that washing clothes emits microfibers into wastewater, the environmental impact of drying is unknown.
According to a pilot study published in ACS’ Environmental Science & Technology Letters, a single dryer can emit up to 120 million microfibers per year – far more than washing machines.
Microfibers can be made from natural fabrics like cotton or synthetic materials like polyester, which are also microplastics.
The release of microfibers into the environment is a problem since they have the ability to adsorb and transmit contaminants over great distances. In addition, if the fibers are swallowed or inhaled, they might cause irritation.
Previous research has revealed that microfibers are released into laundry water by clothes washers, but this waste is processed, eliminating some or most of the fibers before the water is discharged into rivers or streams.
However, nothing is known about whether dryers, whose air goes through a duct and is vented directly to the outside, are a significant source of microfiber and microplastic contamination in the environment.
Thus, Kai Zhang, Kenneth Leung, and colleagues set out to count the microfibers produced by cotton and polyester garments in a dryer in order to determine the amount of laundry released into the outdoor air each year by a home.
The researchers dried polyester and cotton garments separately in a tumble dryer with a vent pipe to the outside. As the machine ran for 15 minutes, they accumulated and recorded the airborne particles that came out of the vent.
The findings revealed that both types of clothing produced microfibers, which the researchers believe is due to friction caused by clothes rubbing against each other as they tumbled around.
In the previous studies, depending on the fabric, the dryer generated between 1.4 and 40 times the number of microscopic pieces that were previously generated by washing machines for the same amount of clothing.
They also discovered that the release of polyester microfibers rises as the load size increases, whereas the release of cotton microfibers remains constant.
According to the researchers, this occurs because certain cotton microfibers cluster and are unable to remain airborne, a process that does not occur with polyester.
Finally, the researchers determined that the average single Canadian household’s dryer produces between 90 and 120 million microfibers each year and releases them into the air outside.
To keep these airborne microfibers from getting into the air, more filtration systems should be added to dryer vents, the researchers say.
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