You’ve already inhaled thousands of microscopic particles today. Some will be dust, pollen or soot, and some are plastic. Microplastics – tiny fragments shed from clothes, tyres or packaging – have been found pretty much everywhere. They’re in oceans, soils, wildlife, remote mountaintops and deep-sea trenches and the atmosphere is no exception.
But how much plastic are we really breathing in? And should we be worried?
A modelling study published in the journal Nature earlier this year suggests the answer may be more complicated – and perhaps less alarming – than previously thought. Measuring this atmospheric microplastic remains difficult, however, and scientists haven’t yet agreed on exactly how to do it.
The particles come from many different sources, including road dust generated by tyre wear, sea spray, or agricultural soil dust, disturbed by wind and farming activities. Indoors, the major source is textiles, particularly synthetic fabrics. Your fleece or your leggings will shed fibres during everyday use.
As plastics fragment into ever smaller pieces, detection becomes increasingly difficult. Current methods struggle to identify the smallest particles, meaning they are probably underestimated and, in the very smallest cases, remain largely theoretical.
Estimating microplastics in the air
Scientists can’t measure every microscopic particle directly, so they rely partly on computer models that estimate how much plastic enters the environment, how it breaks down into smaller pieces, and how these particles move through the atmosphere. Different models led to different estimations of anywhere between 324,000 tonnes and around 10 million tonnes entering the air each year.
But real-world measurements didn’t find as much plastic in the atmosphere as these models predicted – not even close. After adjusting the flawed models to match the real-world measurements, the scientists behind the Nature paper came up with a much lower estimate: around 4,500 tonnes per year.
Why were the earlier estimates so much higher? The authors argue that previous models probably overestimated emissions from land-based sources such as car tyres or textiles. Those models had to make assumptions about how much plastic difference sources released and the sizes of the particles they produce – two things scientists still don’t know with confidence.
The Nature modelling study uses revised assumptions that better match what’s actually being found in the atmosphere. But this research is unlikely to be the final word. In a few years, with better data and more understanding, we may find ourselves having a similar conversation about another more refined estimate.
Different researchers looking at different things
The scientists behind the new study emphasise the lack of a “universal sampling protocol” for microplastics, including those found in the atmosphere. Different studies collect different particles in different ways, and this makes comparisons between them difficult. Some sample particles suspended in the air using pumps, while others collect particles that settle onto surfaces over time.
The samples are then examined under a microscope to identify features like colour and size, before chemical tests confirm whether the particles are actually plastic and if so which polymer they are made from.
Because studies use different equipment, focus on different size particles, and have different reporting methods, the results are often not directly comparable. This makes it much harder to estimate how much plastic people are actually breathing in.
Should we be worried?
Microplastics have been found throughout the human body, including in the blood and lungs. This naturally raises questions about the health effects. However, detecting microplastics is not the same thing as demonstrating they are harmful.
For now, researchers cannot say that the levels of airborne microplastics people typically inhale are causing diseases. What we can say is that evidence from laboratory experiments increasingly shows that these particles are linked to inflammation and a risk of damage to DNA and cells, though these experiments don’t necessarily reflect everyday life.
What needs to be done next
A few simple changes would help researchers make progress on atmospheric microplastics. We should have internationally agreed standards for sampling, analysis and reporting, for instance. This would mean the data generated is better quality and more easily comparable.
We’ll need studies that track the health harms of exposure over the long-term – not just on us, but on plants, animals and ecosystems too. And we need more research looking at the original sources of this microplastic and how it gets into the environment. This will help us develop better strategies for mitigating the problem.
Atmospheric microplastics are out there, and people are inhaling them every day. But we still don’t know exactly how much is in the air or what effect it will have on our health. Better measurements will help us answer that question. For now, the evidence does not support panic, but it does justify concern.
The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.