Does a surgical helmet provide protection against aerosol transmitted disease?

Background and purpose — The COVID-19 pandemic caused by infection with SARS-CoV-2 has led to a global shortage of personal protective equipment (PPE). Various alternatives to ordinary PPE have been suggested to reduce transmission, which is primarily through droplets and aerosols. For many years orthopedic surgeons have been using surgical helmets as personal protection against blood-borne pathogens during arthroplasty surgery. We have investigated the possibility of using the Stryker Flyte surgical helmet as a respiratory protective device against airborne- and droplet-transmitted disease, since the helmet shares many features with powered air-purifying respirators. Materials and methods — Using an aerosol particle generator, we determined the filtration capacity of the Stryker Flyte helmet by placing particle counters measuring the concentrations of 0.3, 0.5, and 5 µm particles inside and outside of the helmet. Results — We found that the helmet has insufficient capacity for filtrating aerosol particles, and, for 0.3 µm sized particles, we even recorded an accumulation of particles inside the helmet. Interpretation — We conclude that the Stryker Flyte surgical helmet should not be used as a respiratory protective device when there is a risk for exposure to aerosol containing SARS-CoV-2, the virus causing COVID-19, in accordance with the recommendation from the manufacturer