We may be inhaling 68,000 microplastics every day

New measurements of fine microplastic particles suspended in the air in homes and cars suggest that humans may be inhaling far greater amounts of lung-penetrating microplastics than previously thought, according to a study published in the journal PLOS One.

Prior research has detected tiny fragments of plastic known as microplastics suspended in the air across a wide variety of outdoor and indoor environments worldwide. The ubiquity of these airborne pollutants has raised concerns about their potential health effects, as small-sized inhaled microplastic particles may penetrate the lungs and release toxic additives that pose risks of oxidative stress, immune-system effects and organ damage. However, prior research on airborne microplastics has mostly focused on larger particles ranging from 20–200 µm in diameter, which are less likely to penetrate the lungs than particles of 10 µm across or less.

To help improve understanding of the risk of microplastic inhalation, Nadiia Yakovenko and colleagues at the Université de Toulouse collected air samples from their own apartments, as well as from their own cars in realistic driving conditions. They used Raman spectroscopy to measure concentrations of microplastics, including those from 1–10 µm across, in 16 air samples.

The researchers found that the median concentration of detected microplastics in the apartment air samples was 528 particles/m³, while in the cars it was 2238 particles/m³ (the researchers acknowledge that there was high variability of microplastic concentration in both environments). Furthermore, 94% of the detected particles were smaller than 10 µm.

The researchers then combined their results with previously published data on exposure to indoor microplastics, estimating that adults inhale about 3200 microplastic particles per day in the range of 10–300 µm across, and 68,000 particles of 1–10 µm per day — 100 times more than prior estimates for small-diameter exposures. The authors thus suggest that the health risks posed by inhalation of lung-penetrating microplastics may be higher than previously thought, although further research will be needed to confirm and expand on these results.

“We found that over 90% of the microplastic particles in indoor air across both homes and cars were smaller than 10 µm, small enough to be inhaled deep into the lungs,” the authors said. “This was also the first study to measure microplastics in the car cabin environment, and overall, we detected indoor concentrations up to 100 times higher than previous extrapolated estimates, revealing indoor air as a major and previously underestimated exposure route of fine particulate microplastic inhalation.”

Image caption: Electron microscope image of a quartz fibre filter with numerous micrometre-sized microplastic indoor dust particles. Image background has been altered from the original, which is credited to Nadiia Yakovenko under CC-BY 4.0