Microplastics in household dust and indoor air: what we know

Most microplastics coverage pictures oceans, turtles and beaches. The plastic you’re most consistently close to is probably on your living-room floor, drifting past your nose and settling on your dinner.

People spend about 90% of their time indoors, by one common estimate, and indoors is where the synthetic stuff lives: polyester sofas, nylon carpets, acrylic jumpers, fleece blankets. All of it sheds. Researchers have been measuring what ends up in indoor air and dust for less than a decade, and the picture is still rough. Here’s what they’ve found, how sure they are, and what’s worth doing about it.

Indoor air carries more plastic than outdoor air

The first study to compare the two was published in 2017. They sampled air in two apartments and one office, plus one outdoor site. Indoor air held 1.0 to 60.0 fibres per cubic metre, against 0.3 to 1.5 outdoors. Those counts include natural fibres like cotton. About a third of the indoor fibres were petrochemical, mostly polypropylene. It was a small study, but it set the pattern later work keeps finding.

Fibres also settle. The same team estimated that 1,586 to 11,130 fibres landed on each square metre of indoor surface every day, building up to 190 to 670 fibres per milligram of the dust in vacuum cleaner bags.

Later studies counted plastic specifically:

• In three Danish apartments, researchers used a breathing mannequin that simulates a person’s body heat and breathing. It drew in air containing 1.7 to 16.2 microplastic particles per cubic metre. Polyester made up 81% of the synthetic particles.
• A study of homes, workplaces and public transport found an average of 4.8 particles per cubic metre in houses and 17.3 on buses, mostly polyamide (nylon) and polyester, the polymers of synthetic clothing.
• When a team in Toulouse, France, looked for much smaller particles (1 to 10 micrometres, the size that reaches deep into the lungs), the counts jumped. They found a median of 528 particles per cubic metre in apartments and 2,238 in cars. 94% of the particles were under 10 micrometres.

That last jump isn’t a sign that Toulouse is filthy. It shows that the answer depends on how small you can see. Smaller particles are more numerous, and older methods simply missed them.

And dust is full of it

Household dust collects what falls out of the air, plus what we track in. In the biggest survey so far, researchers analysed 286 dust samples from 12 countries for two plastics: PET (the polymer in polyester fabric and drinks bottles) and polycarbonate. PET-based particles turned up in every sample, from 38 to 120,000 micrograms per gram of dust, with a median of 5,900. At the median, that’s roughly half a percent of the dust by weight.

A Sydney study collected dust settling in 32 homes over a month. It found 22 to 6,169 microplastic fibres landing per square metre per day, and 39% of fibres were petrochemical. Homes with carpet as the main floor covering had more polyethylene, polyester, nylon, acrylic and polystyrene fibres.

Dust doesn’t stay on the floor. In a UK study that set out to measure plastic in mussels, the researchers also measured fibres falling onto a dinner plate indoors. They estimated that a person swallows 13,731 to 68,415 fibre particles a year from household dust settling on meals, compared with about 123 a year from eating mussels. That’s a modelled estimate from one setting. Still, it’s a good reminder that the dinner table may matter more than the seafood counter.

Where it comes from

The polymers found indoors are the polymers we furnish and dress ourselves in. Polyester dominated the Danish samples. Polyamide and polyester dominated the Spanish ones. Carpeted homes in Sydney had more synthetic fibre types.

Clothes shed simply by being worn. A study of polyester garments found that the fibres people release into the air through everyday wear are of a similar order of magnitude to what laundering sends down the drain. Fabric construction mattered. A tightly woven fabric made from long, highly twisted filaments shed the least. Loose knits made from short fibres shed the most.

Researchers haven’t yet ranked indoor sources. Nobody can tell you how much comes from your sofa versus your sweater versus your carpet.

How much do we breathe in? Nobody knows within a factor of 100

This is the most uncertain part of the topic, so we’ll be blunt about it.

The Danish mannequin study estimated that, at its most contaminated location, a man doing light activity could inhale up to 272 microplastic particles in 24 hours. That counted only particles 11 micrometres and larger.

The Toulouse team, combining their small-particle data with published indoor measurements, estimated that an adult inhales about 3,200 particles a day in the 10 to 300 micrometre range, and 68,000 a day in the 1 to 10 micrometre range. By their own account, that small-particle estimate is about 100 times higher than earlier extrapolations. It also rests on seven samples from three apartments.

Meanwhile, a probabilistic model combining food, drink and inhalation put median total intake at 883 particles a day for adults and 553 for children. Those authors also checked the much-repeated “credit card a week” figure, an early WWF estimate, and found it sits above the 99th percentile of their distribution. It doesn’t describe a typical person.

So the honest answer is somewhere between hundreds and tens of thousands of particles a day, depending mostly on the smallest size the lab can detect. A count also isn’t a dose. A breathed-in particle may be coughed up, or caught in mucus and swallowed. Its size and chemistry probably matter more than the raw number.

Plastic has been found in human lungs

In a 2022 study from Hull, researchers analysed 13 lung tissue samples, taken from 11 living patients during thoracic surgery, and found 39 microplastic particles in 11 of the samples. That works out to an average of 1.42 particles per gram of tissue, or 0.69 after subtracting the background contamination found in lab blanks. The most common were polypropylene, PET and resin. Levels were highest in the lower part of the lung. Some fibres were over 2 millimetres long, which the authors note is larger than they expected to reach that deep.

A Brazilian study of lung tissue taken at autopsy found polymer particles or fibres in 13 of 20 samples, mostly polyethylene and polypropylene.

Here’s what these studies don’t show. They don’t show that the plastic caused any disease. They didn’t measure health outcomes. The Hull team had no data on patients’ smoking or jobs, and the patients were having surgery for cancer or severe lung disease, so they’re not a random sample of anyone. Both are small studies. What they do show is that inhaled plastic can reach and stay in human lung tissue. The Hull authors frame their work as a basis for realistic lab experiments to find out what it does there. Those experiments haven’t been done yet.

The clearest human evidence of harm comes from a different setting: workplaces. Respiratory symptoms and disease have been reported in people exposed to occupational levels of microplastics in industry. Synthetic fibres have also been found in textile workers’ lungs. Those exposures are far higher than in a typical home, so they tell us the mechanism is plausible, not that household levels are harmful. For the wider picture of plastic in the body, see our explainer on microplastics inside you.

Why children get more

Small children live closer to the floor and put their hands and toys in their mouths. The US EPA’s exposure handbook notes that children ingest soil and dust through hand-to-mouth movements and by mouthing objects or eating food that has dropped on the floor.

Apply that to plastic-laden dust and the modelled numbers climb. The 12-country study estimated that infants’ median daily intake of PET-based particles from dust ranged from 4,000 to 150,000 nanograms per kilogram of body weight. The Sydney study put ingestion from dust at 6.1 mg per kilogram of body weight per year for ages 1 to 6, against 0.5 for adults over 20. The first indoor-fibre study had already flagged dust ingestion as a concern “particularly for young children”.

These are modelled exposure estimates, not measurements of what’s inside children, and none of them comes with a known safe or harmful level.

What we don’t know yet

• The real dose. Inhalation estimates span more than two orders of magnitude, and methods for the smallest particles are new.
• Health effects at household levels. No study has linked indoor microplastic exposure to a disease outcome in the general population.
• Which sources matter most. Textiles are the leading suspect, but nobody has ranked carpets, furniture and clothing.
• Whether household habits change exposure. We found no study showing that a cleaning routine lowers what a person breathes or swallows.
• What the particles carry. Additives and absorbed pollutants may matter as much as the plastic itself, but they’re barely studied in indoor dust.

What to do about it

None of the steps below has been shown to improve anyone’s health. A few have a little direct evidence. Most are cheap precautions that follow from where the plastic comes from. We’ll label which is which.

• Ventilate when you can (reasoned precaution). Indoor air tends to carry more plastic than outdoor air, so swapping it out should dilute it. In one office study, an air cleaner lowered indoor plastic levels relative to outdoors, but running electric fans alongside it worked against it. So air movement isn’t automatically your friend.
• Vacuum with a HEPA filter (precaution). Dust is where plastic accumulates, and a sealed HEPA vacuum is designed to catch fine particles rather than blow them back out. No study yet shows it lowers microplastic exposure specifically.
• Damp-dust and damp-mop (precaution). A damp cloth picks up dust instead of launching it back into the air. This is the same logic used for other household dust contaminants, untested for microplastics.
• Keep floors clean where kids play and eat (precaution, strongest rationale). Children’s hand-to-mouth habits are the best-documented reason dust exposure differs between people.
• Choose natural fibres when you’re replacing things anyway (precaution). Synthetic textiles are the leading source, and carpeted homes in Sydney had more kinds of synthetic fibre. A wool or cotton rug won’t make your house plastic-free, but it’s one less shedding surface. Don’t bin a perfectly good sofa for this.
• Wash and tumble synthetics a bit less (mainly for rivers, not your lungs). Washing less often cuts what goes down the drain. For indoor air, wearing synthetics sheds about as much as washing them, and tightly woven fabrics shed less than loose knits or fleece.

Our standards page explains how we grade evidence, and the home section has more. The bigger fix is upstream. The polyester study concluded that changing how textiles are designed is likely to work better than trying to catch fibres after they’re shed. That’s a job for the fashion and furniture industries, not your vacuum cleaner.