Particle emission rates and conditions of use for the cutting of biobased composite polyurethane foam

Background: Nanofillers improve polyurethane (PU) foam properties, such as thermal conductivity, mechanical properties, thermal and chemical stability, and reduce swelling. Mechanical reworking is used to shape nano-enabled PU foam material, which can result in emissions and inhalation exposure. Released fragments containing nanofillers can pose an increased risk, particularly due to inhalation exposure. This study investigates emissions from cutting bio-based composite PU panels containing functionalized silica, GasBeton ®, and Diatomite nanofillers, and assesses the conditions of use (CoU) for the cutting process. Methods: Concentrations were measured at the cutting site (near field; NF) and far field (FF). Process-specific concentrations were calculated for the NF and FF concentrations, and mass balance was used to calculate the cutting process emissions. The CoU assessment was conducted using the emission component with the highest risk potential. The CoU was specified as the maximum cutting rate (m 2/min) under reasonable worst-case (RWC) operational conditions where the NF concentration is <0.5×OEL and <1×OEL. Results: Cutting released mainly inhalable particles, with a geometric mass mean diameter of 10 µm. Aggregated average cutting emissions were 410±65 µg/min, resulting in an emission factor of 4600±730 µg/m 2 when using a unit density for mass concentration calculation (precautionary approach). Under RWC conditions (room volume 100 m 3, particle loss rate 2 1/h, NF volume 8 m 3, worker in NF, and air mixing flow between NF and FF 9.6 m 3/min), chemical-specific hazard communication is sufficient action if the cutting rate is <1.42 m 2/min, corresponding to 210 cut panels during an 8-hour work shift. The maximum cutting rate resulting in NF concentration <1×OEL was 2.84 m 2/min (420 panels). Conclusions: This study presents a method for assessing emission rates in real working conditions and quantifying broadly applicable CoU. The assessment complies with the REACH legislation criteria given for chemical safety assessment.