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

The COVID-19 pandemic has highlighted the need for improved air flow in hospitals, to reduce the transmission of airborne infections such as COVID-19. The aim of this review was to map the existing literature on intervention used to improve air flow in hospitals, understanding challenges in implementation and the findings of any evaluations. We reviewed peer-reviewed articles identified on three databases, MEDLINE, Web of Science and the Cochrane Library with no restriction on date. 5846 articles were identified, 130 were reviewed and 18 were included: ten articles were from databases and eight articles were identified through hand searching. Results were discussed in terms of three categories: (i) concentration of aerosol particles, (ii) changes in/effect of air speed and ventilation and (iii) improvements or reduction in health conditions. Eight studies included an evaluation, the majority only had one comparator condition however three had multiple conditions. The most common device or method that was outlined by researchers was HEPA filters, which can remove particles with a size of 3 microns. Articles outline different interventions to improve air flow and some demonstrate their effectiveness in terms of improving health outcomes for patients, they also suggest either mechanical and natural ventilation are the best methods for dispersing particulate matter as well as perhaps two air cleaning units rather than one. With different methods comes different strengths and weaknesses however, the key finding is that air flow improvement measures reduce the likelihood of nosocomial infections.