HEPA filters of portable air cleaners as a tool for the surveillance of SARS‐CoV‐2

Studies about the identification of SARS‐CoV‐2 in indoor aerosols have been conducted in hospital patient rooms and to a lesser extent in nonhealthcare environments. In these studies, people were already infected with SARS‐CoV‐2. However, in the present study, we investigated the presence of SARS‐CoV‐2 in HEPA filters housed in portable air cleaners (PACs) located in places with apparently healthy people to prevent possible outbreaks. A method for detecting the presence of SARS‐CoV‐2 RNA in HEPA filters was developed and validated. The study was conducted for 13 weeks in three indoor environments: school, nursery, and a household of a social health center, all in Ciudad Real, Spain. The environmental monitoring of the presence of SARS‐CoV‐2 was conducted in HEPA filters and other surfaces of these indoor spaces for a selective screening in asymptomatic population groups. The objective was to limit outbreaks at an early stage. One HEPA filter tested positive in the social health center. After analysis by RT‐PCR of SARS‐CoV‐2 in residents and healthcare workers, one worker tested positive. Therefore, this study provides direct evidence of virus‐containing aerosols trapped in HEPA filters and the possibility of using these PACs for environmental monitoring of SARS‐CoV‐2 while they remove airborne aerosols and trap the virus.