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The use of a portable air cleaner significantly reduces aerosol exposure to SARS-CoV-2 in a meeting scenario, according to a new study from the Centers for Disease Control and Prevention.

Investigators created a conference room scenario with a simulated infected meeting participant who was exhaling aerosols, two simulated uninfected participants and a simulated uninfected speaker. When two high-efficiency particulate air, or HEPA, air cleaners were used near the “speaker,” the exposure of the uninfected participants was reduced by up to 65%. Masking alone also was very effective, reducing exposure by 75%, the researchers noted.

But the combination of HEPA air filters and universal masking was more effective that either intervention alone — cutting exposure by 90%, reported first author William G. Lindsley, Ph.D., of the National Institute for Occupational Safety and Health of the CDC.

Although the effectiveness of ventilation in reducing exposure to infectious aerosols is well-established, not all building ventilation systems are designed with the higher airflow rates needed to reduce disease transmission, the authors wrote.

Adding portable HEPA air cleaners to rooms without existing HVAC systems may be a simple option for increasing the filtration of aerosol particles from a room without the need to overhaul the building’s ventilation system, Lindsley and co-authors wrote. 

“The optimal location for HEPA air cleaners will depend upon the unique conditions in each room, but they are likely to be most effective when they are placed as close to the occupants as is practicable,” they added.

“These findings support the utility of portable HEPA air cleaners and universal masking for reducing exposure to indoor aerosols containing SARS-CoV-2. Efforts to reduce SARS-CoV-2 aerosol exposure could help limit transmission of the virus and decrease incidences of COVID-19 illness and death,” they concluded.

The full report was published on the CDC’s website.