Laboratory study of physical barrier efficiency for worker protection against SARS-CoV-2 while standing or sitting

Transparent barriers were installed as a response to the SARS-COV-2 pandemic in many customer-facing industries. Transparent barriers are an engineering control that intercept particles traveling between customers and workers. Information on the effectiveness of these barriers against aerosols is limited. In this study, a cough simulator was used to represent a cough from a customer. Two optical particle counters were used (one on each side of the barrier, labeled customer and worker) to determine the number of particles that migrated around a transparent barrier. Ten configurations were tested with six replicates for both sitting and standing scenarios, representing nail salons and grocery stores, respectively. Barrier efficiency was calculated using a ratio of the particle count results (customer/worker). Barriers had better efficiency (up to 93%) when its top was 9 to 39 cm above cough height and its width was at least 91 cm. Barriers that extended 91 cm above table height for both scenarios blocked 71% or more of the particles between 0.35-0.725 µm and 68% for particles between 1 to 3 µm. A barrier that blocked an initial cough was effective at reducing particle counts. While the width of the barriers was not as significant as the height in determining barrier efficiency it is important that a barrier be placed where interactions between customers and workers are most frequent. Bystander exposure was not taken into consideration along with other limitations.