Correlations between indoor polyethylene terephthalate, polyamide microplastics, air pollutants and inflammatory factors in exhaled breath condensate among Chinese healthy youth

Microplastics and air pollution are both critical public health issues. This longitudinal panel study aimed to investigate the correlations and interactions among indoor polyethylene terephthalate (PET) and polyamide (PA, primarily PA6 and PA6,6) microplastics, outdoor air pollution, and inflammatory factors in exhaled breath condensate (EBC). Indoor microplastic levels were measured using high-performance liquid chromatography (HPLC) after depolymerization of PET and PA into terephthalic acid (TPA), 6-aminohexanoic acid (AHA), and 1,6-hexamethylenediamine (HMDA), respectively. Results indicated that PET, PA6, and PA6,6 microplastics were detectable in most indoor air deposition samples, with average levels of 13.11 (± 7.25) μg/m2/d, 5.06 (± 5.13) μg/m2/d, and 2.93 (± 4.36) μg/m2/d, respectively. Linear mixed-effects models revealed positive correlations between exposure to PET and PA microplastics and inflammatory markers in EBC, with these associations varying by gender. Furthermore, interactive effects were observed between indoor PET, PA microplastics and outdoor air pollutants on the level of interleukin-6 (IL-6) in EBC. These findings underscore the importance of controlling both microplastic and air pollution.