A comprehensive characterization of indoor ambient microplastics in households during the COVID-19 pandemic

Abstract Airborne microplastics (MPs) can be easily inhaled by humans, impacting their health as they spend more than 80% of their time indoors, especially during the pandemic. Only a few research studies have examined indoor MPs in the micrometer size range using active sampling, and studies have mainly concentrated on MPs that are millimeters in size. This study investigated the composition of indoor airborne MPs by active sampling in seven houses in the city center of northwestern Turkey (Eskişehir) during the COVID-19 pandemic. The visual identification showed the presence of different colored MPs, white, red, orange, green, and yellow, with different shapes (fibers, fragments, films, lines, foam, and pellets). The size of the identified MPs was between 2.5 and 327.36 μm. The polymeric composition analysis showed the presence of 123 MPs in all the samples with 22 different polymeric compositions. Residents in these houses are exposed to airborne MPs, with inhalation estimates ranging from 12.03 to 18.51 MPs/m 3 . However, it was also estimated that humans inhale 156–240 MPs daily in these houses. The dominant MPs were polyamide 6, polyvinyl chloride, polypropylene, ethylene propylene, polystyrene, and high-density polyethylene. Scanning electron microscopy energy dispersive x-ray elemental analysis revealed the presence of common structural elements, additives, or vectors that are added or adsorbed to MPs like carbon, oxygen, fluorine, magnesium, silicon, chlorine, nitrogen, and aluminum. These indoor environments are prone to MP pollution. Still, the MP level varies due to different characteristics of indoor environments, like activities and the number of occupants/people in the space, etc. The smaller MPs in all the samples highlight the necessity for standardized techniques of MP collection.