see through barriers used to only be seen in high security areas. Now they're everywhere plexi glass walls erected to stop the spread of coronavirus. Both the CDC and OSHA do recommend the use of plexi glass and other barriers and work environments to reduce direct spread of potentially infectious droplets between people, especially in manufacturing, retail or food service settings where physical distancing might not be possible. Even though these recommendations air in place, there is surprisingly little science that supports their use or that gives clear guidance on the best design. Now, intuitively, Ah, barriers should be effective at stopping droplets that are expelled when a person talks, coughs or sneezes and because they'll become covered in those droplets and they should be cleaned regularly. The effectiveness against small aerosols that hang in the air for minutes to hours and they could move around the barrier, if it isn't large enough, is simply unclear. In many ways, it's a similar circumstances. The question over the effectiveness of face shields, recent analysis has shown. While they do block large droplets, aerosols can travel around them