Design and Evaluation of a Portable Negative Pressure Hood with HEPA Filtration to Protect Health Care Workers Treating Patients with Transmissible Respiratory Infections

Phu, Hai-Thien; Park, Yensil; Andrews, Austin J.; Marabella, Ian; Abraham, Asish; Mimmack, Reid; Olson, Bernard A.; Chaika, Jonathan; Floersch, Eugene; Konia, Mojca; Hume, Janet R.; Fischer, Gwenyth A.; Belani, Kumar; Hogan, Christopher J.

BACKGROUND: To mitigate potential exposure of healthcare workers (HCWs) to SARS-CoV-2 via aerosol routes, we have developed a portable hood which not only creates a barrier between HCW and patient, but also utilizes negative pressure with filtration of aerosols by a HEPA filter. MATERIAL AND METHODS: The hood has iris-port openings for access to the patient, and an opening large enough for a patient's head and upper torso. The top of the hood is a HEPA filter connected to a blower to apply negative pressure. We determined the aerosol penetration from outside to inside in laboratory experiments. RESULTS: The penetration of particles from within the hood to the breathing zones of HCWs outside the hood was near 10(-4) (0.01%) in the 200-400 nm size range, and near 10(-3) (0.1%) for smaller particles. Penetration values for particles in the 500 nm – 5 μm range were below 10(-2) (1%). Fluorometric analysis of deposited fluorescein particles on the personal protective equipment of a HCW revealed that negative pressure reduces particle deposition both outside and inside the hood. CONCLUSIONS: We find that negative pressure hoods can be effective controls to mitigate aerosol exposure to HCWs, while simultaneously allowing access to patients.