Effect of a barrier on spatial distribution of respiratory particles in a room

Barriers have been widely used to mitigate transmission of Covid-19 and other diseases. Their efficacy for aerosol particles is not well established. The objective of this study was to quantify the impact of a barrier on the spatial distribution of particles released by speaking in a room with a low air-change rate (0.6 +/- 0.2 h(-1)). The source was a nebulizer that released fluorescent microspheres of diameters 0.5, 1, 6, 10, or 20 mu m for 20 min, and the room was outfitted with 108 passive sampling sites. We counted the number of microspheres deposited on slides at sampling locations after >1 h. The presence of a barrier 0.46 m in front of the source resulted in an increase in 0.5 mu m particles deposited on the source-side of the barrier and an increase in 0.5 mu m particles around the sides of the barrier laterally and at certain locations 4-6 m from the source. The barrier had a minor effect on the distribution of 1 mu m particles. There was no observable effect of the barrier on the distribution of 6, 10, and 20 mu m particles. Most 10 and 20 mu m particles deposited within 0.3 m of the source, although some were found at locations >3 m from the source. These results indicate that barriers may not serve as adequate protection to others in the room, depending on their location relative to the barrier and the exposure timescale. A limitation is that our study utilized only one barrier configuration at one air-change rate.

Automated summary

Barriers have been effective in mitigating the transmission of diseases, but their efficacy for aerosol particles is still uncertain. This study aimed to assess the impact of a barrier on the spatial distribution of particles released by speaking in a room with low air-change rate. The results showed that the barrier had some effect on the distribution of 0.5 μm particles, but no significant impact on particles of other sizes.