Pyroplastic particulate matter from fire events adds a hidden dimension of plastic pollution

Wildfires and structural fires increasingly involve synthetic materials, yet plastic transformation during combustion remains poorly understood. Here we characterise plastic-derived particulate matter generated during fire events, termed pyroplastic particulate matter (PyP-PM): airborne micro- to nanoscale particles from thermal degradation of synthetic polymers, comprising carbonized polymer matrices enriched with combustion-derived toxicants and additives, particularly the inhalable fraction ( < 10 μm). PyP-PM is physicochemically and toxicologically distinct from conventional micro- and nanoplastics (MNPs): a carbonaceous soot core bears adsorbed polycyclic aromatic hydrocarbons (PAHs) and heavy metals, conferring elevated oxidative potential, alongside environmentally persistent free radicals (EPFRs) that extend particle reactivity in the atmosphere. Generated during wildfires, structural fires, and open burning at wildland-urban interfaces (WUI), PyP-PM combines MNP environmental persistence with the toxicity of combustion by-products and additives. This review outlines PyP-PM formation pathways, chemistry, and dispersion, emphasising long-range atmospheric transport and accumulation in ecosystems and human lungs. We identify research gaps, including the absence of standardised detection methods, limited toxicological evidence (particularly on neuroinflammatory pathways), and poor integration of PyP-PM into fire and air-quality models. Recognising PyP-PM as an emergent pollutant at the climate-fire-plastic nexus is essential for advancing monitoring frameworks, informing fire management policy, and protecting vulnerable communities from fire-driven pollution. Thermal degradation of plastics during wildfires, structural fires, and waste burning releases airborne particles containing altered polymers, combustion pollutants, and additives, highlighting the climate–fire–plastic nexus, based on a review assessing pyroplastic as an emerging pollutant.