New filtration systems would prevent spread of microplastics into the environment, scientists say
On the same day British MP Alberto Costa raised in parliament the issue of washing machines releasing plastic microfibres into the atmosphere, a new study reveals that drying machines could be significantly worse.
Mr Costa, the MP for South Leicestershire, is calling for microplastic filters to be fitted to all new washing machines in the UK, in order to reduce the amount of plastic particles going into the environment.
But according to a study by the American Chemical Society, a single clothes dryer could discharge up to 120 million microfibres a year, which the researchers said this was “considerably more than from washing machines”.
The research team said that while it has long been known that washing machines release microfibres into wastewater, it has been unclear how drying impacts the environment beyond energy usage.
Microfibres can come from natural fabrics, such as cotton, or synthetic ones, such as polyester — which are also considered to be microplastics.
The scientists said: “Releasing microfibres into the environment is a concern because they can absorb and transport pollutants long distances. And the fibers themselves can be irritants if they are ingested or inhaled.
“Previous studies have shown that microfibres are released from clothes washers into laundry water, but this waste is treated, removing some or most of the fibres before the water is discharged into rivers or streams.”
But they said little research had previously been done into dryers, whose air passes through a duct and is vented directly to the outdoors, and hypothesised they are an important source of airborne microfibers and microplastic contamination in nature.
The research team, including Professor Kenneth Leung from the City University of Hong Kong, and Kai Zhang from the American Chemical Society’, wanted to count the microfibres 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.
In order to do this, 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 revealed that both types of clothing produced microfibres, which the team suggested 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 microfibres increases with more clothes in the dryer, whereas the release of cotton microfibres remains constant regardless of the load size.
The researchers said they believed this occurs because some cotton microfibres aggregate and cannot stay airborne, a process that doesn’t happen for polyester.
The team estimated that between 90 and 120 million microfibres are produced and released into the air outside by the average single Canadian household’s dryer every year.
They said that in order to control and reduce the release of these airborne microfibres, additional filtration systems should be adapted for dryer vents.