Clothes dryers are an underappreciated source of airborne microfibers
Nobody likes their favorite clothes having holes or breaking after many wash cycles. But what happens to the shards of fabric and sewing that come off? Although washing clothes is known to release microfibers into wastewater, it is unclear how drying affects the environment. Now, a pilot study at ACS’ Environmental science and technology messages Reports suggest that a single dryer can vacuum up to 120 million microfibers per year—much more than washing machines.
Microfibers can come from natural fabrics, such as cotton, or synthetic fabrics, such as polyester – which are also considered microplastics. The release of microfibers into the environment is a concern because they can absorb pollutants and transmit them over long distances. And the fiber itself can be irritating if ingested or inhaled. Previous studies have shown that microfibers from washing machines are released into the wash water, but this waste is processed, removing some or most of the fibers before the water drains into rivers or streams. However, there is very little information on whether dryers, whose air passes through a duct and vented directly to the open air, are a significant source of airborne microfibers and microplastic pollution in nature. Therefore, Kai Zhang, Kenneth Leung and their colleagues wanted to count the microfibers generated by cotton and polyester clothes in a dryer to estimate the amount released into the outdoor air of a home laundry each year.
The researchers separately dried polyester and cotton clothes in a ventilated clothes dryer to the open air. While the machine was running for 15 minutes, they collected and counted airborne particles that exited the vent. The results showed that both types of clothing produced microfibers, which the team suggests comes from rubbing the clothing together as it flips over. For both fabrics, the dryer released between 1.4 and 40 times more microscopic splinters than what was produced by the washing machines in previous studies for the same amount of clothes. They also found that the release of polyester microfiber increased with the increase of clothes in the dryer, while the release of cotton microfiber remained constant regardless of the load size. The researchers suggest that this happens because some of the cotton microfibers collect and cannot stay in the air, a process that does not happen with polyester. Finally, the team estimated that between 90 and 120 million microfibers are produced and released into the air outside by the average Canadian household dryer each year. The researchers say that to control the release of these airborne microfibers, additional filtration systems must be adapted to dryer vents.
Reference: “microfibers released into the air of a household clothes dryer” Jan 12, 2022, Available here. Environmental science and technology messages.
DOI: 10.1021 / acs.estlett.1c00911
The authors acknowledge funding from the State Key Marine Pollution Laboratory; the Innovation and Technology Commission of the Hong Kong Special Administrative Region of the People’s Republic of China; Discovery Scholarship from the Natural Sciences and Engineering Research Council of Canada; Western economic diversification in Canada; Infrastructure Canada; Canadian Research Chair Program of the Natural Sciences and Engineering Council of Canada; One of the authors was supported by the Distinguished Visiting Professor at Baylor University.