Dryer Vents Blow Hot Air & Microplastics

New research confirms that air vents on tumble dryers – rather than washing machines – may be a leading source of microplastic fibers from clothing in the environment. The findings, presented in a new report by the San Francisco Estuary Institute, provide convincing reason to hang-dry clothes and to use energy-intensive dryers sparingly, if ever. 

Microplastics have emerged in recent years as one of the most concerning forms of pollution, with the insidious little particles being found, among other places, in ocean-caught fish, beer, and even placentas of unborn babies.

Kelly Moran, an SFEI senior scientist and the lead author of the report, says emerging science on microplastic fiber sources also creates a significant regional divide between the people of the United States and Canada and those of the much of the rest of the world, including Europe and New Zealand.

“Tumble dryers aren’t widely used there,” she says, explaining that people in these regions tend to hang-dry their clothes or use gentler, less abrasive – and more energy-efficient – ventless dryer machines. Rather than spew out hot – and fiber-laden – air, ventless dryers recirculate heated air inside the system while draining out evaporated water. 

“These geographic differences may explain why dryer vents are an under-studied source of microplastic pollution,” Moran and her colleagues suggest in their 137-page analysis. The authors also cite research suggesting that some dryers may cause 3.5 times the shedding of microplastic fibers that some washers do.

Microplastic fibers vented from clothes dryers may be especially problematic in the United States. That’s because Americans’ household wastewater is typically processed in treatment plants which remove most plastic particles, whereas dryer-released fibers exiting buildings can be washed into storm drains that flow directly to creeks. Many European communities, Moran says, have a different system entirely by which storm drains empty into wastewater treatment plants.

The SFEI’s report suggests regulatory action that could help mitigate microplastic pollution. Moran and her colleagues propose stricter standards on apparel fabric quality to reduce shedding. Filtration systems on dryer vents could also be improved to reduce microfiber emissions. They also encourage governments to ease restrictions on using outdoor clotheslines to dry clothes.

Moran says voluntary action at the individual level will also be helpful, primarily by avoiding dryer use when possible. “If you don’t have outdoor space, use an indoor folding rack – that’s what I do,” she says. 

Though such solutions are seemingly obvious, reducing environmental pollution while improving energy efficiency and climate resilience, significant change will probably not come easily. “It’s difficult to change our lifestyles,” Moran says. “There’s a big gap between knowing what the solution is and doing it.”

More

• A Synthesis of Microplastic Pathways and Sources in Urban Runoff, San Francisco Estuary Institute 2021
• Your Laundry and Plastic Pollution, CBC Radio 2019
• The Fabric Cycle, Envirobites, November 2021