Adults may inhale an estimated 68,000 microplastic particles per day from indoor air—nearly 100 times more than previously believed, according to a recent study.
Lead author Nadiia Yakovenko of Géosciences Environnement Toulouse, CNRS/IRD/Université de Toulouse in France and fellow researchers quantified human exposure to inhalable indoor microplastics (MPs) in a study by combining direct measurements from 16 air samples with modeled estimates based on published data.
Using Raman spectroscopy with a lower detection limit of 1 µm, the team measured suspended MP concentrations in residential apartments and car cabin environments, focusing on particles within the respirable 1 to 10 µm range (MP1–10 µm), which can penetrate the lower respiratory tract.
The samples were from 3 apartments and 2 vehicles and included blanks. They were collected using active air sampling through 47 mm PTFE filters, followed by extraction and Raman analysis of a 1 mm² central filter area.
After correcting for background contamination and recovery rates (81% ± 3%), the researchers extrapolated findings to estimate total airborne MP concentrations. The median concentration of suspended indoor MPs across all environments was 1,877 MPs/m³. Concentrations were notably higher in car cabins (median = 2,238 MPs/m³) than in residential spaces (median = 528 MPs/m³). The highest value was observed during high human activity (34,404 MPs/m³).
Among the MPs identified, 94% were within the MP1–10 µm range, and 97% were classified as fragments. Polyethylene (76%) was the dominant polymer in residential samples, while polyamide (25%) and acrylonitrile butadiene styrene (19%) were most common in vehicle interiors. The researchers used a power law size distribution model to integrate their findings with published data. They estimated mean indoor air concentrations of 4,300 ± 2,200 MPs/m³ for MP1–10 µm and 200 ± 180 MPs/m³ for MP10–300 µm.
Based on European Union-recommended inhalation rates, the team calculated daily MP1–10 µm inhalation exposures of 47,000 ± 28,000 particles for children and 68,000 ± 40,000 particles for adults. These estimates were nearly 100-fold higher than those derived from previous studies that were limited to larger particles. Estimated inhalation of MP10–300 µm was 2,200 ± 2,000 for children and 3,200 ± 2,900 for adults.
"Consequently, human inhalation of fine particulate MP1–10 µm, and likely [nanoplastic], that penetrate deep lung tissue may contribute to causing lung tissue damage, inflammation and associated diseases," the authors concluded. They recommended further investigation of microplastic inhalation at MP1–10 µm in epidemiologic and occupational health studies to better characterize exposure and potential health effects.
The authors reported no conflicts of interest
Source: PLOS One
