Emission of airborne particles from 3D printing using thermoplastic polymeric materials

3D printing activities are recognized to emit airborne particles. Several papers in scientific literature quantified the particle emission for different filament materials; nonetheless, a knowledge gap still exists for some advanced materials. To this end, we evaluated the particle emissions from a 3D printer using thermoplastic polymeric materials, including thermoplastic elastomer (TPE), thermoplastic polyurethane (TPU), thermoplastic polyurethane enhanced with carbon nanotubes (TPU-CNT), polycarbonate (PC), and polypropylene (PP). Data for various printing temperatures and printing chamber configurations (open and closed with a HEPA filter) were provided. For all the investigated materials and temperatures, negligible emissions in terms of PM were recognized. Particle number emission rates with the chamber closed were one order of magnitude lower than those for tests with the chamber open. A temperature effect was also detected; higher emission rates and lower particle distribution modes were estimated for higher extrusion temperatures. Amongst the tested materials, PP and PC filaments presented the highest emission factors (up to 1 × 1012 part. min-1 for open printing chamber). The obtained emission rates were adopted to estimate the average particle number concentration in a real-world scenario when performing 3D printing activities: in a 40 m3 office, when printing chambers with HEPA filters are adopted, the 1-hour average concentration is lower than the WHO guideline value, regardless of the filament and the air exchange rates. On the contrary, without a printing chamber, the WHO guideline values are only met with less emitting filaments and high ventilation rates.