Abstract

During the recent COVID-19 pandemic, several temporary negative pressure isolation (TNPI) wards that converted from the general wards of existing medical facilities by installing portable HEPA filter units (PHUs) have been reported. The purpose of this study is to analyses the indoor environment and performance in these TNPI wards through on-site measurement and experiments. As a result, it was found that there are some expected spread routes and cause of infectious agents in TNPI area. That concerns about leakage or backflow due to duct pressure imbalance at unsealed diffusers as PHUs installed. And when there is a pressure difference between adjacent wards planned with the same pressure level, the spread through the leakages was found. Furthermore, possibility of movement through the plenum space and by “short-circuit” that the exhausted air is re-introduced into the TNPI area was presumed.