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PLOS ONE is delighted to introduce a new Curated Collection – Recent Advances in Understanding Plastic Pollution. This global challenge may have not been the biggest fixture in the media during the past couple of years, but researchers, governments, volunteers and the public have all been working hard on ensuring that it is easier than ever to be a part of the movement to reduce plastic pollution. Many of us will now be used to receiving take-away food in paper bags or boxes and being equipped with wooden forks and spoons instead of the traditional plastic ones. The PLOS ONE community of researchers working on plastic pollution have been busy reporting new results on identifying microplastic prevalence in various organisms and habitats, understanding how members of the public understand recycling and bioplastics, and how clothes shed microfibers during washing and drying. You can learn more about all of this in our new Curated Collection.
In this first installment of our Q&A with authors from this collection, we speak to some of our researchers working on how clothes may contribute to microfiber pollution during washing and drying.
Dr Neil Lant joined Procter & Gamble’s Newcastle Innovation Centre in 1997 after completing a chemistry degree and PhD in bioorganic chemistry. For the past 25 years he has worked in fabric and home care product development for all regions of the world, with a strong emphasis on applying new enzyme technology to improve product performance and sustainability, resulting in over 150 families patent applications. He also leads P&G’s microfiber research program, as part of his broader interests in the role of fabric care products in improving textile sustainability.
Neil Lant’s paper in this Curated Collection: Lant NJ, Defaye MMA, Smith AJ, Kechi-Okafor C, Dean JR, Sheridan KJ (2022) The impact of fabric conditioning products and lint filter pore size on airborne microfiber pollution arising from tumble drying. PLoS ONE 17(4): e0265912. https://doi.org/10.1371/journal.pone.0265912
PLOS: Your studied microfiber shedding from clothes during various washing and drying conditions. You made a distinction between European and North American washing routines. What is the main difference between these? How do they differ from those in other parts of the world that were not studied?
NL: The washing machines used in Europe are almost exclusively front-loaders with a wash water volume of around 13 litres. However, in North America several very different appliance types are being used, broadly falling into three types – (i) front loaders that are essentially larger versions of European machines, (ii) traditional top-loading machines that have a large water volume of around 64 litres and (iii) high efficiency top-loading machines with a water volume of around 32 litres. We have found that microfiber release is driven by many factors but our previous publications were the first to recognise that the ratio of water volume to fabric weight was particularly important with high water to fabric ratios causing the highest levels of release. For this reason we run testing in both European and top-loading North America machines to check that the same trends are observed in very different conditions. Other appliance types are used in different regions of the world, and many consumers still wash by hand, but the European and North American washing machines are good representatives of those used in markets where tumble drying is common, as in this paper we were mainly interested in microfiber release during the drying step.
PLOS: You mention in this study that the only real solution to microfiber shedding may be to design a completely different type of dryer. What would need to be the key differences, and how close are we to being able to developing something like that?
NL: The study was focused on airborne microfiber pollution arising from vented dryers which have a air duct to the outside of the building, which is the most important type of dryer in North America with over 95% of the market. The airborne microfiber release can be eliminated by either improving the removal of fibers from that air flow (e.g. using the cyclonic filtration process used in many vacuum cleaners) or moving to fully sealed condenser dryers that collect all fibres and moisture within the appliance. The only problem with the latter is that the fibers can end up in the condensed water or on the condenser which is typically washed in a sink, running the risk of solving an air pollution issue by increasing water pollution! This suggests that we might need to redesign all tumble dryers to ensure that all fibers can be collected and disposed in household waste, with no opportunity for fibers to be released to the air or water.
PLOS: You studied how clothes shed during washing and drying. We also know that clothes shed microfibers whilst we wear them. Do we know how the microfiber release for a certain garment differs during washing vs drying vs wearing?
NL: Forensic scientists have known for a long time that fabrics lose fibers when they make contact with other surfaces, but loss of fibers to the air and their transfer to other surfaces has now been proven. We also know that fibers will be lost during line drying of clothes. Although textile scientists are gaining a better understanding of the relationship between fiber, yarn, and textile construction and microfiber shedding during washing, more research will be needed to understand whether the same principles apply to other modes of microfiber release. And we still don’t have a clear understanding of the relative quantities of microfibers being released from textiles to air and water from these sources nor the ultimate fate of these fibers. However, there is a clear consensus that steps to reduce the intrinsic ‘sheddability’ of clothing will be a move in the right direction and we anticipate future government legislation to drive any changes needed in textile manufacturing, in line with proposed legislation in several markets to include microfiber filters in new washing machines.
PLOS: Several other studies in this Collection also look the effects of plastic pollution on living species. One of these is “Kapp KJ, Miller RZ (2020) Electric clothes dryers: An underestimated source of microfiber pollution. PLoS ONE 15(10): e0239165. https://doi.org/10.1371/journal.pone.0239165” Has seeing these other research studies in the collection helped inspire any thoughts about future work you might do, or other advances your research community will make?
NL: Kapp and Miller’s article was a breakthrough in being the first to recognise, and begin to quantify, the contribution of vented tumble dryers to airborne (and subsequent terrestrial) pollution. Their methods involving use of snow to collect deposited microfibers were fantastic. As their study only involved two dryers and didn’t measure the relative quantities of microfibers being released during washing and drying, we were keen to build on that study with a more extensive program spanning different markets, impact of fabric care products, and evaluating some potential solutions. The quantity of literature focused on tumble drying is still very limited so we would like to continue researching this area with an emphasis on condenser dryers which are already very common outside of North America and, when integrated with heat pump technology, are much more energy efficient resulting in lower operating costs and reduced carbon footprint.
Stay tuned for more interviews with authors from this collection, including Kapp and Miller who contributed Electric clothes dryers: An underestimated source of microfiber pollution
Cover image: Port of Dover, 2014 Beach Clean (CC-BY 2.0)
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