Point of emission air filtration enhances protection of health care workers against skin contamination with virus aerosol

Rationale: We recently demonstrated that a patient hood with a high efficiency particulate air filter eliminates virus aerosol contamination when very large quantities of bacteriophage virus are aerosolised into a clinical room. While this containment method is relatively low cost, it is unclear whether similar efficacy can be achieved with lower cost/commercial grade air purifiers, or if such an approach protects healthcare workers against virus aerosol contamination. Method: A total of 109 (10 ml of 108) PhiX174 bacteriophages was nebulized into a sealed clinical room. Surface contamination was detected by settle plates left uncovered during exposure. A healthcare worker remained in the room, personal exposure was determined by skin swabs after exiting the room, following doffing of personal protective equipment (PPE). Four skin areas were swabbed: forearms/hands, neck, forehead, under N95 mask. Three conditions were tested, 1) hood with hospital grade air purifier (IQ Air Health Pro 250), 2) hood with commercial air purifier (Philips 1000i), and 3) control (no hood/air-purification). Findings: The control condition demonstrated extensive environmental and limited skin contamination underneath PPE, which was highest under an N95 mask. The commercial air purifier and hood provided environmental control of virus aerosol and almost zero skin contamination. In comparison, the hospital grade purifier provided complete environmental and skin contamination protection, despite a lower clean air filtration rate (240m3/hr vs 270m3/hr). Virus counts on plates and swabs were significantly lower for both air purifiers and across neck, forehead, and under the N95. There were no statistically significant differences in detected virus counts between air purifiers. Conclusion: This cheap and scalable method may be an effective way to reduce the spread of COVID-19 in hospitals by enhancing the effectiveness of PPE worn by health care workers who care for COVID-19 patients and who are exposed to virus aerosol.