Hong Kong Study: Tumble Clothes Dryers Generate Air Pollution from Microfibers

By Jerri-Lynn Scofield, who has worked as a securities lawyer and a derivatives trader. She is currently writing a book about textile artisans.

Microfibers – pieces of microplastics less than 5 mm in length – are now virtually ubiquitous, found in pristine environments such as the Arctic, as well as in human placentas.

Their impact on human health has not been well studied,  although recent research suggests they may be dangerous, as The Guardian noted in Tumble dryers found to be a leading source of microfibre air pollution.:

…In 2021, scientists found microplastics caused damage to human cells in the laboratory. These tiny fibres have also been linked to intestinal inflammation and other gut problems.

A study published this week, Microfibers Released into the Air from a Household Tumble Dryer, found that a single home clothes dryer could release up to 120 million such particles into the air each year, making microfibers so released a leading source of such air pollution (see full study here.)

The study was conducted by a group led by Prof. Kenneth Leung, director of the State Key Laboratory of Marine Pollution (SKLMP) and department of chemistry at City University of Hong Kong. Per the abstract:

This study quantified the number of the two most common textile fibers discharged from a household vented tumble dryer to ambient air. The results suggest that driers of this type are a potential source of air contamination by microfibers, releasing 433,128–561,810 microfibers during 15 min of use. Microfibers can be generated from both polyester and cotton textiles. The abundances of microfibers of polyester produced were directly proportional to the masses of clothing loaded into a dryer, but such a relationship was not apparent for cotton textiles. On the basis of the results presented here and other relevant data, it was estimated that the average Canadian household can annually release from 9 × 107 to 12 × 107 microfibers from a single dryer. To minimize the release of these microfibers into the air, an appropriate engineered filtration system should be developed and adopted as an effective control measure for individual household driers.

Both organic – e.g., cotton – and inorganic – polyester – shed microfibers when clothes are tumble dried. The natural fibres can be digested and decompose relatively quickly. The inorganic fibres are more problematic. Per the study:

Cotton microfibers discharged into the environment can be ingested by organisms, but they are not as persistent as polyester microfibers. For the same drying duration, cotton textiles produce more stable amounts of microfibers (165 ± 27) after drying regardless of the mass of textiles in the dryer. In comparison, polyester textiles can generate more microfibers than cotton textiles according to the current results. Micro- fibers generated from polyester textiles are of special concern since their bioaccumulation potential increases with decreasing size. The microfibers might be ingested by organisms ranging from zooplankton to fish and birds and transferred into food webs. [Jerri-Lynn here: my emphasis; study p. D, citations omitted.]

Professor Leung told The Guardian that filtering such pollutants is a relatively simple exercise:

“Once we know the source, we can begin to control it using simple methods,” said Leung, the lead author of the study published in the journal Environmental Science & Technology Letters.

Leung’s team has designed filtration systems that prevent washing machines from dispersing microfibres and is now working on similar systems for clothes dryers.

The challenge arises when it comes to dispose of the microfibers that the filters  collect: Over to The Guardian:

“These [filter systems] effectively remove most of the microfibres from the laundry,” he said. However, it is still unclear where these microplastics would end up when the filters were cleaned.
“If people just put these [fibres] in the dustbin, some of the fibres will be released back into the air,” he said. “We suggest the particles should be collected in a bag.”

The question of course is: where does that bag go? Because if it’s simple tossed into a landfill those microfibers will make their way into the ecosystem.

Filters per se are not a complete solution. Instead, Leung noted:

Even if fitting these filters is “possible, as Leung says, microfibres will still be pervasive until the clothing industry uses more environmentally friendly fabrics.

To be sure, the study suggested that when comparing the tumble drying of organic and inorganic fibers, cotton appears superior to polyester. Yet as I’ve written previously, merely shifting production from inorganic fibers to cotton creates its own set of environmental concerns. Current varieties of the most commercially popular cotton are notoriously thirsty plants, and considerable quantities of pesticides are also employed in most cotton production. While organic cotton production dispenses with the pesticides, the thirst issue remains. Reviving traditional Indian cotton varieties holds out some promise in addressing  these issues, yet at present, the scale of such initiatives is minuscule, and alone they couldn’t supply world cotton demand any time soon ( see Growing Cotton: One Small Sustainable Solution to the World Plastics Problem.)

Perhaps another possible short-term solution might be to air dry clothing – doing so cuts back on the fossil fuels necessary to run dryers. My mother used a clothes line during the temperate New Jersey summers of my youth. Yet with temperatures hovering below freezing today in much of the Northeast, clothes hung out to dry would freeze before they dried. Additionally, although Leung et al’s study only addressed tumble drying, I believe his team has also found washers also generate microfibers, so even eliminating clothes dryers completely wouldn’t solve the problem.

Leung et al’s study makes it clear that the typical household clothes dryer generates a considerable quantity of microfibers. Alas, sorting out what should be done to collect and dispose of these fibers properly is not a straightforward task.


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  1. Nikkikat

    I have been hanging most laundry for years. I noticed that our clothing became thinner and thinner. The more you washed and dried the more your clothes became almost see-through. All that lint captured in the dryer screen is your shirt slowly disappearing.
    Some of that would of course be microscopic, evading the lint screen.

    1. Jerri-Lynn Scofield Post author

      We have a small laundry room adjacent to the kitchen and hang up collared shirts and dresses on hangers to dry there throughout the year, summer and winter alike. Doing so reduces wear and tear. Linens, t-shirts, and underwear all go through the tumble dryer; most of those are made of 100% cotton.

  2. Joe Well

    Re: air drying clothing

    I was amazed when I lived in a very damp South American city where the clothes would take up to three days to dry on the line and would end up smelling slightly musty, that people were still horrified by the idea of a clothes dryer because of the waste of energy. Launderettes had clothes dryers that usually ran on gas (a giant flame under the rotating steel drum) so people knew about them, but it would be like having your own pizza oven.

    Which is just to say that we don’t in fact *need* a clothes dryer, it really is just a *want.*

    >>Yet with temperatures hovering below freezing today in much of the Northeast, clothes hung out to dry would freeze before they dried.

    People dry clothes indoors all the time on those wooden racks in the US, and usually on big plastic or metal ones in other countries. That’s how they do it in South America. Clothes dry better in a US winter because the air is dryer.

    1. Jerri-Lynn Scofield Post author

      Yes, I do that too when I’m in Brooklyn, see my comment above, but using hangers in the laundry room, rather than on a wooden rack.

      And when I’m in India, where I’ve spent lots of time over the last several years, especially in Calcutta, my clothes are hand washed in a bucket. Then I send them out to be ironed by a man who has a small nearby kiosk. He charges me the equivalent of 15 cents per piece to iron clothes perfectly and I’m more than happy to pay that.

  3. onihikage

    Both organic – e.g., cotton – and organic – polyester

    Should be inorganic for the second one.

    Washers generating microfibers seems like a natural consequence of cloth fibers being soft and easily damaged; washing by hand would likely generate nearly as much, if not more, while also wasting hours of someone’s time. I’d expect those fibers to be bound up by the water and have nothing to do with air quality, anyway; rather, the water is being polluted instead if the drain doesn’t lead to a treatment plant.

    1. JIG

      Both are technically organic from a chemical standpoint. The better description would be natural for cotton and synthetic for polyester.

      1. Jerri-Lynn Scofield Post author

        Thanks for your comment. I’ll make sure future posts reflect this better description.

  4. T_Reg

    Yet with temperatures hovering below freezing today in much of the Northeast, clothes hung out to dry would freeze before they dried.

    I’m not in the North, but it seems that freeze-drying is actually a thing.

    Those jeans you hung out turn into stiff denim icicles. Are they really dry? Yes! Drying on a line in winter is actually a form of freeze-drying thanks to sublimation – or ice evaporating from a solid state. Wet clothing may freeze, but the moisture evaporates into water vapor leaving behind dry clothing that just needs a little loosening.

    Here in the Southeast, humidity is the bigger problem. Usually it just means more patience is needed, but sometimes days isn’t enough. (This assumes that there is some protection from the rain).

    I hate the way cotton is produced, but at least it doesn’t result in immortal microscopic plastic.

  5. Pat

    A small fan in the room with the drying clothes will speed up drying. While blowing directly on them is quickest, even indirect air circulation speeds drying. Considering the subject of the post, you might not want direct, but it is well worth it to keep air moving for more than just its aid in drying clothes.

  6. Arizona Slim

    Wow, NC, you are GOOD. How did you know that I’m running a load of laundry right now?

    Where will that load go? Out to my clothesline!

    What I don’t hang outside gets air-dried in the house. That’s because there is no dryer here at the Arizona Slim Ranch.

  7. Katiebird

    I stopped tumble drying clothes in the early 70s when I realized I was throwing away the fibers of my clothes when I threw away the lint. … I’m still wearing a couple of things from those days. dryers destroy clothes

  8. Eclair

    I find myself becoming increasingly grumpy with middle-class whining over how we can’t live without: personal automobiles, plastic containers, clothes driers, strawberries in January in NYC. How do you think humans made it to 1900? OK, got that out of my system.

    My husband, the rocket engineer, has refused to use a clothes drier forever. We were fortunate (?) enough to spend decades in Southern California and Colorado, where a heavy towel would dry in less than an hour. Unless it was rainy season. He has always taken care of his laundry and now that we are retired, I do the sorting (white, off-white, tan, beige ……) and washing and he does the hanging and folding.

    When I first read about plastic microfibers, especially from fleece, about a decade or more ago, I stopped buying fleece products. I did love my polar fleece outerwear and poly thermal base layers for hiking, camping and biking! Discovered exorbitantly priced merino wool base layers and scrounged through thrift stores for real wool sweaters. Took to wearing two to three layers of wool ….. indoors ….. after we moved to Denver and bought a large, drafty house (because it was on the rocket guy’s preferred bicycle route to work …. but that’s another story), built in the hey-day 80’s when fuel was cheap and the sky was the limit.

    Now, after retirement (and moving back to damp climates), we still air dry clothes. Well, I cheat in the winter and put bedding and towels in the dryer. Our Amish neighbors in western NY and Pennsylvania manage to air dry their clothes all year. The family clothes line, running from an elevated porch to the corner of a barn or shed, works on pulleys, and is an integral part of every Amish house design. They don’t have closets full of clothes. Actually, they don’t have closets! Just a set of wooden pegs.

    I love our modern ‘labor-saving’ appliances: central hot water, refrigerator/ freezers, automatic clothes washers and dryers, dishwashers. It has allowed a couple of generations of women to get money in exchange for work. Me, along with other ‘working’ moms, would get home from 8 or 9 or 10 hours at ‘work,’ pop a frozen pizza in the oven, put the dishes in the dishwasher, throw a wash in, play a game with the kids, fall into bed, get up, having set the automatic coffee maker to brew at 6 am, throw the wash in the dryer, take a hot shower while the kids popped their tarts in the automatic toaster, give the kids their clean shirts still warm from the dryer, then roar off in the battered VW Rabbit to another day at ‘work.’

    We humans don’t ‘need’ closets full of clothes. We don’t ‘need’ thermostats set at 72 degrees in winter while we swan around in shorts and cotton tees. (Especially while some of us get to live in buildings with no heat.) We don’t ‘need’ 20 minute daily showers (looking at you, teenagers :-)) We don’t ‘need’ 27 varieties of toothpaste (sorry, had to get that beef out there!)

    Maybe all this whining about ‘stuff’ is a form of mourning. A realization that most, if not all, of this is going to disappear. For most of us. This so-called ‘American way of life,’ has already disappeared for tens of thousands of homeless citizens. And it was never there for the Indigenous peoples of the land. The Amish have never bought into the American Dream, teaching that contentment and self-worth arise from strong family and community bonds and a faith in God, and not from the number of shoes you own or the price of your stock portfolio.

    Now, I wouldn’t last five minutes in the Amish way of life. Patriarchy, God, and all that. And, they do love them some of the less savory parts of civilization, like plastics and refined sugar. But, their form of socialism is worth studying. And maybe even emulating, as we face massive climate disruption and the inevitable social upheaval that will follow.

  9. KLG

    J. Matthew Sleeth, MD, wrote Serve God, Save the Planet in ~2007. He convinced me to air-dry shirts because the lint in the trap is your clothing disappearing, not to mention the energy saved. His more recent book of a similar title must be an update. A good place to start, I would imagine.

  10. John

    Don’t own and only occasionally use a dryer in the laundromat. Waste of energy and nothing smells better than air/sun dried laundry. Freeze dried jeans and canvas shirts may take a couple days on the line. Cotton underwear on a line on the porch much shorter time.
    Laundry for me in India and Nepal was mostly in a bucket on shower floor. Every 10th time or so I’d splurge and send it out…for after all Hari was a Dobi. He beats us on a rock by the river and cleans our soul.;-)

  11. Julia

    Thank you so much, Jerri-Lynn and NC, for this info. I use drying racks for clothes, sheets, and towels. The “Sheila Maid” drying rack might work for some people–it hangs from your ceiling and looks so cool. I have a collection of incredibly warm, polyester fleece-lined sweats that allows me to work from home without using my heater. I used to always be cold and could never have functioned at 58 degrees, which is my home’s current temperature. Now I’m fine. I use a “Guppy Friend” bag to wash my polyester fleece clothing and really hope that my much lower energy consumption outweighs the downside of all that polyester.

  12. Charlotte

    A great compact outdoor line is made by Versaline from Australia. Mine was kind of spendy, but I’ve been using it for nearly 20 years now. It folds flat against the surface when you’re not using it. For winter, I strung clothesline from my basement rafters, and my sweetheart has a series of temporary lines he uses at his vacation rental cabin. Saves your clothes, saves energy, and saves your neighbors.
    Here’s a piece I wrote about it at Dark Mountain a couple of years back: https://dark-mountain.net/dark-mountain-issue-11-clothesline-at-the-end-of-the-world/

  13. anon y'mouse

    now i’m wondering about sunlight santisation of laundry prior to washing, thus removing the need for hot water or bleach.

    anyone lucky enough to have an airing cupboard?

    or a california food cabinet? oooh

  14. chuck roast

    I use a couple of clothes racks. Haven’t used a dryer in decades. Even when I had to schlep my clothes to laundromat, I schleped the damp clothes back home to the racks. Good humidifier in the winter; not so much in the summer. Of course it’s “no class” to hang your wash on a clothesline these day. All the more reason to string a couple lines.

  15. Grebo

    I line dry my laundry down here in the tropics. When the line is not out in the sun it can take a couple of days due to the humidity and it can get a bit smelly in that time, presumably due to the cold water wash not killing all the bacteria. The solution to that is to add a little bleach to the wash.

  16. sd

    SoCal – We have an outdoor clothes line – its actually faster to dry the clothes on the line than in the dryer. Pretty much just use the dryer for cotton bath towels. We also prefer the feel of the clothes from the line – and yes, clothing seems to last much longer if it is air dried.

  17. marieann

    We line dry laundry in the summer and hang in the basement in the winter…the bonus in the dry winter is extra humidity. We have a dryer that doesn’t get much use.

  18. The Pale Scot

    Yet with temperatures hovering below freezing today in much of the Northeast, clothes hung out to dry would freeze before they dried

    That’s not true, Nana hung her wash outside in Bayonne NJ year around. Takes more time but in happens. And Bayonne is between NY harbor and Newark bay, the winters were wet. It has some thing to do with partial pressure IIRC

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