Dust laced with plastic
When tiny fragments of plastic settle from the air, they often end up in household dust.
Even though dust settles, it can easily get kicked up into the air when disturbed by any sort of friction. Jeroen Sonke, a biogeochemist at the French National Center for Scientific Research who co-authored a recent study on indoor airborne microplastics, investigated the presence of small microplastics in the range of one to 10 micrometres, which penetrate deeper into the lungs than larger fragments.
Sonke and his colleagues looked inside three of their own apartments in Toulouse, France, to take samples, and collected further samples from inside two cars (where people in developed countries typically spend another 5% of their time). Sonke was surprised to find an average of more than 500 fragments in one cubic metre of air indoors, and more than 2,200 fragments inside the cabin of a car. He noted that these samples were mainly from stagnant air, but if people were present stirring up dust, the air would likely have many more microplastics.
For a baby crawling on the ground, their faces can be inches away from microplastic-filled dust. Sonke and his colleagues calculated the amount of microplastics an infant may inhale on an average day ranged between 19,000 and 75,000 particles in the 1-10 micrometre range. For adults, it was 28,000 to 108,000 particles a day.
These numbers come with a caveat: it remains challenging for scientists to unequivocally measure the amount of microplastics in the air. "There's no gold standard approach for measuring microplastics, and there may never be," says Douglas Walker, an associate professor of environmental health at Emory College, noting this makes it difficult to compare findings between studies.
And it's especially hard to measure smaller microplastics, which can find their way deeper into the lungs. Standard microscopes tend to have a lower limit of around 20 micrometres, though the technology is improving, Sonke notes. The method his team used (Raman microscopy) allowed them to get down to the 1 micrometre microplastic range for the first time.
Contamination also complicates the picture. The clothes scientists wear, which release clouds of microplastics, make it hard to get reliable results. Even the coating on latex gloves that scientists often wear during experimental work can accidentally influence samples, one study found.
Clothes, soft furnishings and carpets
Microplastics come in all different shapes and sizes, including spheres, flakes, foams and fragments. The predominant type of airborne microplastics come from textiles, such as the clothes we wear, the upholstered chairs and sofas we sit on, and the carpets we walk on.
"Indoors we do surround ourselves with lots of plastic materials, and things like upholstery, your furniture, your curtains, your bedding, your clothing, are all things that undergo daily wear and tear," says Stephanie Wright, a microplastics researcher and associate professor in the Faculty of Medicine at Imperial College London. "So literally as we use them, as we sit on them, as we move on them, as we wash them, as we hoover them – all these mechanical ways in which we wear them down generate microplastic as well."
These microplastics take the form of tiny fibres, and they're generated in the home more or less wherever plastic fibres are heated or come under friction.
Textile workers
The health risks from textile fibres come into sharp focus when looking at those who work with them day in, day out. A recent study analysing airborne microplastic concentrations in several textile factories found consistently high concentrations of fine particles (0.5 micrometres and smaller) in the air and on factory floors. Some studies have found fragments of that size are responsible for health risks, including respiratory issues such as asthma, lung tissue damage and endocrine disruption.
If you are going to wear synthetic clothes, buying used, second-hand garments may also limit microplastic exposure, although scientists are somewhat divided on this. "Some are saying that used clothes have already shed their loose fibres and are less prone to shedding," says Adrian. "However, others argue that used clothes can accumulate more microplastics from all the washes they've undergone, and fibres can break and weaken over time."
Instead, buying used natural-fibre clothes, such as organic cotton or organic wool products, would be "the gold standard", says Adrian.
After minimising the synthetic textiles around you, a good next step is to try to remove the plastic dust in your home, says Wright.
Vacuuming
A thorough vacuum can suck up microplastics that have settled on your floors and furniture, but it can simultaneously send particles back into the air as you clean. You'll also get a face full when you empty the bag or canister into the bin, says Barr.
Mopping and wiping hard surfaces with a wet cloth before you vacuum can help tamp down microplastics so fewer become airborne, says Barr. However, be wary of the products you use to wipe down surfaces; some cleaning products, such as wipes and sponges, can also generate microplastics.
Air filters and air conditioning
It may be impossible to remove microplastics from the air completely, but some simple home devices can help limit your exposure. Hepa air filters are designed to theoretically remove at least 99.97% of airborne particles around 0.3 micrometres (typically the trickiest size to filter). One study that analysed micro- and nanoplastics alongside other air pollution found that a true Hepa filter could remove over 99% of nanoparticles from the atmosphere.
Not all Hepa air filters are created equal, however. Even if they've met the Hepa standards, their construction and functionality could impact how well they capture plastic particles in the average home. Considering that, if you're going to invest in one, Barr suggests models that have numerous filtering stages.
"They have some coarse areas and then fine filtration areas. The more of those filters you have, the more they're stacked, the better off you're going to be, because you're going to be able to filter out multiple sizes of particles," Barr says. Air filtration systems like this tend to have a larger capacity, allowing for a greater surface area to absorb more particles in a range of sizes.
Air conditioning, meanwhile, may not be so helpful for reducing microplastics. Microplastics accumulate on air conditioning units, one study found, and could distribute microplastics around the room when operating. Strong air conditioning can even increase the emission of microplastics from textiles. A study in Colombia found higher concentrations of microplastics in rooms with air conditioning than those without.
"The thinner the fibre, and the smaller, on average, the fibre is, then the more likely it is to penetrate deeper into our airways, and deeper into the lung," says Wright.
Based on what we know from other types of tiny fibres, those dimensions are problematic, she says, based on what we know about mineral fibres such as asbestos or carbon nanotubes. "We know that those fibres – small enough to javelin down into the air sacs at the end of our airways – are problematic."
More like this:
• Your kitchen is full of microplastics. Here's how to eat less of them
• How do microplastics affect our health?
• What would happen if we stopped using plastic?
For microplastic fibres, the picture is still unclear, says Wright. "Would they cause the same effect? Or the fact that they're flexible, whereas mineral fibres are very rigid, does that make [microplastics] less toxic, less harmful?"
Beyond their potential to interfere with tissues, there's also the concern that microplastics often come with company. They are home to a broad range of bacteria, and may carry other contaminants too. It's been suggested that microplastics might act to amplify the toxicity of other pollutants in the environment. This field of research, however, is still in its early days, and the full effects of microplastics on the body are still not yet understood.
To solve the microplastic pollution crisis will take a lot more than changes within the home – there are plenty of broader sustainability concerns too. If moving to replace synthetic fibres in your home with natural fibres, for instance, there's also the greater water and land use from organic cotton use to think about. Or if choosing to ventilate your home more to usher away microplastics, that pollution is only being pushed outdoors. Short of systemic change and a global reduction from the 460 million tonnes of plastic made each year, there's only so much individuals can do.
"It's tricky, isn't it?" Wright concedes. "Because I feel like in these scenarios, it's pick your battles."
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