Performance of Facepiece Respirators and Surgical Masks Against Surgical Smoke: Simulated Workplace Protection Factor Study

Gao, Shuang; Koehler, Richard H.; Yermakov, Michael; Grinshpun, Sergey A.

OBJECTIVE: Surgical smoke generated during electrocautery contains toxins which may cause adverse health effects to operating room (OR) personnel. The objective of this study was to investigate the performance of surgical masks (SMs), which are routinely used in ORs, more efficient N95 surgical mask respirator (SMRs) and N100 filtering facepiece respirator (FFRs), against surgical smoke. METHODS: Ten subjects were recruited to perform surgical dissections on animal tissue in a simulated OR chamber, using a standard electrocautery device, generating surgical smoke. Six respiratory protective devices (RPDs) were tested: two SMs, two SMRs, and two N100 FFRs [including a newly developed faceseal (FS) prototype]. Fit testing was conducted before the experiment. Each subject was then exposed to the surgical smoke while wearing an RPD under the tests. Concentrations inside (C(in)) and outside (C(out)) of the RPD were measured by a particle size spectrometer. The simulated workplace protection factor (SWPF) was determined by the ratio of C(out) and C(in) for each RPD-wearing subject. RESULTS: For the SMs, the geometric means of SWPF(total) (based on the total aerosol concentration) were 1.49 and 1.76, indicating minimal protection. The SWPF(total) values of the SMRs and N100 FFRs were significantly higher than those of the SMs: for the two SMRs, the SWPF(total) were 208 and 263; for the two N100s, the SWPF(total) values were 1,089 and 2,199. No significant difference was observed between either the two SMs or the two SMRs. The SWPF(total) for the novel FS prototype N100 FFR was significantly higher than the conventional N100 FFR. The correlation between SWPF(total) and fit factor (FF) determined for two N95 SMRs was not significant. CONCLUSIONS: SMs do not provide measurable protection against surgical smoke. SMRs offer considerably improved protection versus SMs, while the N100 FFRs showed significant improvement over the SMRs. The FS prototype offered a higher level of protection than the standard N100 FFR, due to a tighter seal. While we acknowledge that conventional N100 FFRs (equipped with exhalation valves) are not practical for human OR use, the results obtained with the FS prototype demonstrate the potential of the new FS technology for implementation on various types of respirators.