Co-emission of Siloxane Compounds with Polyester Nanofibers from Household Laundry Dryer Exhaust

Airborne nanoplastics (NPs) are an emerging class of environmental contaminants with potential implications for air quality and human exposure, yet their sources remain poorly characterized. Given the widespread use of synthetic fibers in textiles and the recognition of household laundry washing as a major source of nanofibers to aquatic environments, this study aims to investigate emissions and characteristics of airborne polyester nanofibers released from household laundry dryer exhaust. Using online aerosol mass spectrometry (AMS) coupled with particle sizing measurements, particle emissions from drying polyester textiles with fleece-knitted and pile-weave fabric constructions were quantified and chemically resolved. This study presents the first direct observation of the co-emission of airborne polyester nanofibers and siloxane compounds, likely originating from fabric surface treatments. For pile-weave fabrics, major siloxane-related fragments contributed up to 11.5% of the total organic aerosol (OA) mass. Distinct polyester marker ions were reproducibly detected from five different polyester fabrics, but they accounted for less than 3% of the total OA mass measured during the drying process. Particle size measurements revealed an additional coarse mode peaking at approximately 3 µm, indicative of microfiber emissions, although their number concentrations were two orders of magnitude lower than those of nanoparticles peaking near 300 nm. Emission factors showed strong dependence on fabric construction and retained moisture, ranging from 0.1 to 10.5 mg of total organic mass per kilogram of polyester fabric. Under realistic moisture content scenarios, Canada-wide emissions of total organic aerosol from household laundry drying are estimated to be on the order of 1–10 tonnes per year. While this suggests that laundry drying is unlikely to be a major contributor to ambient PM2.5 mass in Canada, the potential human health and environmental implications of co-emitted polyester nanofibers and siloxane compounds warrant further investigation.