LAUSR

Plastics and their breakdown products, specifically microplastics, are ubiquitously present in the environment from a variety of sources. Analysis of air samples has also revealed the presence of fragmented, spherical, and fibrous plastic particles in a wide range of sizes from the submicrometer scale up to tens of micrometers in length and diameter. However, few studies have addressed the health consequences associated with exposures to airborne microplastics, specifically whether they can enter the respiratory tract, where they will deposit, and how polymer chemistry and morphology are linked to adverse health outcomes. Whether microplastics have unique toxicological properties in comparison to other particle types is also unknown. Our work has sought to address critical questions about the inhalability and respirability of microplastics in indoor and outdoor air via particle size-restricted sampling coupled with morphological assessment and estimation of plastic burdens via Nile red staining. We found Nile red-positive (putative plastic) particles in air samples from indoor environments (office, campus/household laundry rooms, 3-D printing/engineering laboratory), most of which appeared to have a fragment-like morphology. These particles represented ~1% of the total collected sample in terms of number. Importantly, these particles were also found when sampling was restricted to the human-respirable fraction (<4 micrometers in aerodynamic diameter), suggesting that they can reach the gas exchange region. Ongoing work is focused on identifying the polymeric species in these air samples, their distribution across particle size classes, and whether indoor and outdoor microplastic particles are similar in terms of morphology, size, and chemistry.