Portable high-efficiency particulate air (HEPA) air cleaners, together with masks, can reduce exposure to SARS-CoV-2 aerosols indoors by 90 per cent, according to the US Centers for Disease Control and Prevention (CDC).
SARS-CoV-2, the virus that causes Covid-19, can be spread by exposure to droplets and aerosols of respiratory fluids that are released by infected persons when they cough, sing, talk, or exhale.
To reduce indoor transmission of SARS-CoV-2 between persons, the CDC recommends measures including maintaining physical distance, universal masking (the use of face masks in public places by everyone who is not fully vaccinated), and increasing room ventilation.
“Ventilation systems can be supplemented with portable high-efficiency particulate air (HEPA) cleaners to reduce the number of airborne infectious particles,” the CDC said in a statement.
Researchers from the CDC used respiratory simulators to mimic a person with Covid-19 and other, uninfected persons in a conference room. They found HEPA air cleaners to be most effective when they were close to the aerosol source.
“Using two HEPA air cleaners close to the aerosol source reduced the aerosol exposure of the uninfected participants and speaker by up to 65 per cent. A combination of HEPA air cleaners and universal masking reduced exposure by up to 90 per cent,” the CDC said.
Ventilation is a well-established method for reducing potential exposures to infectious aerosols. By removing airborne particles from a room, ventilation systems can reduce exposures that occur by inhalation of infectious aerosols, deposition on susceptible mucous membranes, or conveyance to mucous membranes by contaminated hands.
During the ongoing pandemic, public health and professional organisations have provided guidance for increasing ventilation and air filtration to decrease the spread of SARS-CoV-2.The results of this study suggest that portable HEPA air cleaners can reduce exposure to SARS-CoV-2 aerosols in indoor environments, with greater reductions in exposure occurring when used in combination with universal masking, the CDC said.