Exploring the presence of microplastics in lung lavage of respiratory patients and correlation with airborne microplastics

Microplastics (MPs) are becoming well-known as widespread airborne pollutants with potential consequences for human respiratory health. In this study, we examined the occurrence, morphology, and polymer type of MPs in bronchoalveolar lavage fluid (BALF) samples from 30 patients with respiratory issues in a health care setting in southwestern Iran, in relation to airborne MPs collected contemporaneously from the ambient environment. Individual MPs were separated by the use of chemical digestion and density gradient centrifugation; these were analyzed by Raman spectroscopy and scanning electron microscopy (SEM). Overall, 129 MPs were identified in BALF, with a corrected mean of 3.2 particles/10 mL in BALF; however, the majority were white or transparent fibers ranging from a diameter of 20–100 μm, and were predominantly polyethylene (PE), polypropylene (PP), and polystyrene (PS). Air samples, collected using a high-volume OMNI sampler, ranged from 2.2 to 6.7 MP/m³, while in ambient air variation included shapes and colors with fragments, films, and spherules. Additionally, a statistically significant and strong positive correlation (ρ = 0.996 (p < 0.001)) was found between the weekly ambient MP concentration and the BALF MP counts, supporting inhalation as a likely route of exposure. Both morphologically and polymerically, the airborne MPs will likely pass through and deposit in the lower respiratory tract. These findings highlight the necessity of continued biomonitoring and regulatory concern regarding airborne MPs, particularly in urban and clinical environments.