Emission of Atmospheric Nanoplastic Particles and Additives from Plastic Combustion Sources

With the widespread usage of plastics, plastic pollution is becoming a global environmental issue. Approximately 9% of waste plastic is recycled, with the majority ending up in landfills or being incinerated. Due to the unique chemical components, the combustion of plastics can be a potential source of emerging pollutants in the atmosphere. In this study, we investigated the flaming and smoldering combustion of five typical plastics (PE, PP, PS, PET, and PVC) under laboratory conditions. Combining online (PTR-MS, I-CIMS, SP-AMS) and offline (py-GC MS, LC-Orbitrap MS) techniques, we systematically characterized the gas-phase and particulate-phase chemical composition at the molecular level. For the first time, we qualitatively and quantitatively analyzed the nanoplastic particles emitted from plastic combustion. Emission factors of nanoplastic particles varied significantly across different plastic types, ranging from 0.3 to 471 g/kg. Global estimates suggest that the annual flux of nanoplastic particles released from open burning of plastic is approximately 0.34–3.4 Tg, which is comparable to major atmospheric microplastic sources, such as sea-spray and tire wear. This estimate suggests that plastic combustion contributes significantly to the global cycle of atmospheric nanoplastics. We also identified the molecular-level emission of plastic additives, such as plasticizers and organophosphates. Many of these additives have shown higher chemical reactivity and biological toxicity than the plastic polymers themselves, therefore posing risks of complex pollution and combined exposure. Plastic combustion can serve a critical emission source for atmospheric nanoplastics and emerging contaminants, therefore playing an important role in their global burdens.