Use of portable air purifiers to reduce aerosols in hospital settings and cut down the clinical backlog

Abstract

SARS-CoV-2 has severely affected capacity in the NHS, and waiting lists are markedly increasing due to downtime of up to 50 minutes between patient consultations/procedures, to reduce the risk of infection. Ventilation accelerates this air cleaning, but retroactively installing built-in mechanical ventilation is often cost-prohibitive. We investigated the effect of using portable air cleaners (PAC), a low-energy and low-cost alternative, to reduce the concentration of aerosols in typical patient consultation/procedure environments. The experimental setup consisted of an aerosol generator, which mimicked the subject affected by SARS-CoV-19, and an aerosol detector, representing a subject who could potentially contract SARS-CoV-19. Experiments of aerosol dispersion and clearing were undertaken in situ in a variety of rooms with 2 different types of PAC in various combinations and positions. Correct use of PAC can reduce the clearance half-life of aerosols by 82% compared to the same indoor-environment without any ventilation, and at a broadly equivalent rate to built-in mechanical ventilation. In addition, the highest level of aerosol concentration measured when using PAC remains at least 46% lower than that when no mitigation is used, even if the PAC's operation is impeded due to placement under a table. The use of PAC leads to significant reductions in the level of aerosol concentration, associated with transmission of droplet-based airborne diseases. This could enable NHS departments to reduce the downtime between consultations/procedures Initialisms AGPAerosol Generating Procedure APS Aerodynamic Particle Sizer ENT Ear Nose Throat

Interventions used to improve air flow in hospitals – a rapid review

“…One study suggested that air ventilation (open windows) alone was unable to reduce concentrations back to baseline levels without the aid of an AFU, with the ‘windows open, AFU on’ condition producing the lowest concentrations and highest clearance rate of PM2.5 (Fennelly et al, 2022). Salmonsmith et al (2023) reported that PAC mitigation is very effective in clearing the air of aerosols in rooms, this could also reduce the half-life aerosols by 82%, Gola et al (2020) also found that filtration units reduced local airborne loads and suggested they should be used in hard functional areas such as ICUs. As Rezaei et al (2020) looked at cleaning rooms, they identified that a HVAC system provided exhaust air ranging from 50-80 degrees Celsius and with 40-50% humidity, under these conditions COVID-19 was observed to rapidly disappear improving infection control across whole hospitals.…”

Experimental studies on airborne transmission in hospitals: A systematic review

“…67,[72][73][74]83 Under this category, 11 studies investigated the use of personal or localized ventilation units. [85][86][87][88][89][90][91][92][93][94][95] The remaining eight discussed the use of air purifiers and air cleaners with a high-efficiency particulate air (HEPA) filter [96][97][98][99][100][101][102][103] to minimize exposure to infectious aerosols. These experimental studies showed that add-on portable ventilation devices could effectively contain and remove aerosolized particles.…”

Use of portable air purifiers to reduce aerosols in hospital settings and cut down the clinical backlog; a Critical Analysis

“…Reading the article titled ‘Use of portable air purifiers to reduce aerosols in hospital settings and cut down the clinical backlog’ by Jacob Salmonsmith et al [ 1 ] encouraged us to publish a commentary on the extrapolated conclusions regarding the use of portable air cleaners to reduce the concentration of aerosols in patient environments. We hope these perspectives may provide insight into areas that may require further research and improvement.…”

“…In the aforementioned article, the authors summarised that the onset of the Covid-19 virus saw a substantial increase in the patient waiting lists for doctor consultations and procedures in healthcare settings in order to decrease disease transmission [ 1 ]. The researchers proposed that portable air cleaners (PACs) can be a cost-effective alternative to built-in mechanical ventilation systems to reduce potentially infectious aerosol concentrations.…”

“…The researchers proposed that portable air cleaners (PACs) can be a cost-effective alternative to built-in mechanical ventilation systems to reduce potentially infectious aerosol concentrations. The experiment found that the use of PACs significantly reduced aerosol concentrations, which may decrease the risk of disease transmission and potentially lead to a reduction in clinical waiting lists [ 1 ].…”