Washing machines and tumble driers under scrutiny over release of microfibres

Microfibres can come from natural fabrics, such as cotton, or synthetic ones, such as polyester - which are also considered to be microplastics. Releasing microfibres into the environment is a concern because it can present potential health issues. The microfibres also adsorb and transport pollutants long distances and the fibres 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. However, to date, there has been very little information about whether tumble dryers, whose air passes through a duct and is vented directly to the outdoors, are an important atmospheric source of airborne microfibres and microplastic contamination in nature.

Kai Zhang, Kenneth Leung, and colleagues from the American Chemical Society (ACS) wanted to count the microfibres generated by cotton and polyester clothing in a dryer machine to estimate the amount potentially being 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 microfibres, 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 microfibres increases with more clothes in the dryer, whereas the release of cotton microfibres remains constant regardless of the load size. The researchers suggest this occurs because some cotton microfibres aggregate and cannot stay airborne, a process that doesn’t happen for polyester.

Finally, 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. To control the release of these airborne microfibres, additional filtration systems should be adapted for dryer vents, the researchers say.

The study - 'Microfibers Released into the Air from a Household Tumble Dryer' - has been published in ACS’ journal Environmental Science & Technology Letters.

In related news, an exchange in the UK's House of Commons yesterday (January 12) revealed that Defra (the Department for Environment, Food and Rural Affairs) is looking at options to force manufacturers of new washing machines to install plastic filters.

The government is considering introducing legislation that could see new washing machines fitted with microfibre filters to collect tiny pieces of plastic and keep them out of the environment, current Prime Minister Boris Johnson said. Microplastics are typically defined as small plastic pieces, less than five millimetres in length, considered harmful to the oceans and aquatic life.

The issue was raised in the Commons by Alberto Costa, a Conservative MP, who is seeking support for his Private Member's Bill to ensure the latest washing machines are made with the pollution-quashing filters.

Speaking at Prime Minister’s Questions, Costa, the MP for South Leicestershire, said: “Washing machine manufacturers are considering installing microfibre filter systems in all new washing machines.

“Will the Prime Minister ask his minsters to look into the viability of my Bill, which has cross-party support and seeks to introduce inexpensive microplastic filters on all new washing machines?”

Thanking Costa for his campaign, Johnson responded: “I believe that we should tackle microplastic pollution and I’m glad that Defra (Department for Environment, Food and Rural Affairs) are looking at the introduction of legislation for microfibre filters on washing machines as a cost-beneficial solution.

“I will make sure that my right honourable friend, the Secretary of State for the Environment (George Eustice MP), will keep him informed of how we’re doing.”