July 30, 2025

expert reaction to study estimating the number of lung microplastics people inhale daily in homes and cars

A study published in PLOS One estimates human exposure to microplastics in homes and cars. 

Prof Oliver Jones, Professor of Chemistry, RMIT University, said:

“The only thing this paper measured was the concentrations of microplastics in a limited set of environments. The authors tested the air in three apartments and two cars via a total of 12 samples (plus four blanks). This is simply not enough data to make generalisations about the cities in France where the work took place, let alone the rest of the world. The authors did not conduct any testing to determine whether the microplastics they found were associated with or caused any health effects. The results should thus be treated as preliminary at best.

“But what if there were more samples? What would the results mean?

“When we talk about air pollution, you often hear the terms PM10 and PM2.5. The PM stands for particulate matter, and the numbers stand for the diameter of the particle in micrometres (microns). PM10 means particulate matter 10 micrometres (0.01 mm) in diameter or smaller, while PM2.5 means particles of matter 2.5 micrometres (0.0025 mm) in diameter or smaller. They usually come from dust and smoke, and we know that very fine particulate matter, no matter the source, can be a health risk; that’s why air quality is regularly tested, and there are guidelines in place for total PM10 and PM2.5 concentrations in the air in many countries [1].

“Particles at the top end of the PM10 range generally do not travel further into the lungs than the upper respiratory tract (nose and throat). Plastic particles in the PM2.5 range (or smaller) might travel further, but the keyword here is ‘might’; this is a relatively new area of research.

“However, even if we assume plastic PM2.5 were an issue, their effects are already considered as part of the general impact of PM2.5 pollution, and any effect from plastics would likely be dwarfed by the contribution of PM2.5 particles from burning petrol oil and other fossil fuels, which are present in much greater abundance (while a figure like 2238 particles per cubic meter sounds like a large number, the particles themselves are very small, so the total physical amount of particles is also very small).

“In short, while particulate pollution is an issue we should pay attention to, you don’t have to worry about breathing plastic air just yet.

[1] Accredited official statistics, particulate matter (PM10/PM2.5), https://www.gov.uk/government/statistics/air-quality-statistics/concentrations-of-particulate-matter-pm10-and-pm25 accessed 30/06/25″

‘Human exposure to PM10 microplastics in indoor air’ by Nadiia Yakovenko et al. will be published in PLOS One at 19:00 UK time Wednesday 30 July 2025, which is when the embargo will lift.

DOI: 10.1371/journal.pone.0328011

Declared interests

Prof Oliver Jones: I am a Professor of Chemistry at RMIT University in Melbourne. I have previously published research on microplastics in the environment. I have no conflicts of interest to declare but I have received funding from the Environment Protection Authority Victoria and various Australian Water utilities for research into environmental pollution.