Application of a two-zone exposure model to medical laser-generated particulate matter for two simulated surgical procedures

摘要

Background Laser-generated air contaminants from medical procedures have been shown to cause respiratory inflammatory response in animal models, and there is some evidence to suggest bacteria and virus transfer to healthcare personnel. Modeling medical laser-generated particulate matter exposures may be useful in estimating exposure levels in clinical settings during procedures, and in assessing control strategy effectiveness. Aims Our objective was to apply a two-zone exposure model using laboratory-derived particle mass emission rates to estimate particulate mass concentrations in two clinical settings. Methods Particle mass emission rates determined from laboratory-based emission chamber simulated surgical procedures using an Ultra MDTM40 CO2 laser system (Laser Engineering Inc., USA) on porcine tissue were used to inform a two-zone exposure model to determine potential exposures to healthcare personnel. Theoretical procedure rooms were modeled using two room volumes (22.5 and 170 m3), air exchange rates (6 and 15 ACH) and interflow rates between zones (9 and 30 m3/min) to estimate exposures. Results Modeled concentrations for the near-field ranged between 0.03 and 0.5 mg/m3 and between 0.01 and 0.4 mg/m3 for the far-field. The lower air exchange rate led to a doubling of particulate matter concentration in the smaller room volume, but did not have an effect on the concentration in the larger room. Steady state concentration in the larger room volume was reached within fifteen minutes, but continued to rise in the smaller room. Conclusions Concentration estimates in the simulated scenarios were similar to previously reported field assessments in hospital operating rooms. Our results fall below the ACGIH TLV of 10 mg/m3 for inhalable particles and 3 mg/m3 for respirable particles for particulates not otherwise specified, but direct comparison is inappropriate due to the biologically active nature of these particles.