the staff of the Ridgewood blog
Ridgewood NJ, a new CDC MMWR report explores safety precautions that can be taken indoors to reduce transmission of SARS-CoV-2. In particular, the combination of portable high efficiency particulate air (HEPA) cleaners with universal masking policies appears to be very effective in preventing transmission between people in close-contact indoor environments. Previous studies have shown that HEPA air cleaners, portable or built-in, can greatly reduce aerosol transmission in indoor environments.
For the MMWR report, CDC researchers simulated a conference room presentation scenario by using respiratory simulators to mimic a person with COVID-19 as well as other, uninfected persons. When 2 portable HEPA air handlers were used alone, aerosol exposure was reduced by up to 65%. When masks were worn by all simulated participants without air cleaning, the aerosol exposure was reduced by 72%. However, when both air cleaning and masks were employed as mitigation measures, the aerosol exposure was reduced by up to 90%. According to the experiment, the HEPA air cleaners were most effective when placed close to the simulated infected participant. The researchers conclude that portable HEPA air cleaners and masking in combination are viable options to prevent aerosolized SARS-CoV-2 transmission, especially in environments without HVAC systems or other built-in air cleaning technology.