Thank you for linking that interesting article. > We performed a systematic review of both clinical and surrogate exposure data comparing N95 respirators and s

Thank you for linking that interesting article. > We performed a systematic review of both clinical and surrogate exposure data comparing N95 respirators and surgical masks for the prevention of transmissible acute respiratory infections. That it didn't find a difference between N95 and plain surgical masks isn't surprising: > Participants in clinical studies were health care workers in a health care setting. We defined health care worker as any worker in a health care setting who might be exposed to a patient with an acute respiratory infection. [...] Acute respiratory infections may have been acquired during the study from community exposures rather than nosocomial exposure. It's not obvious (and wasn't discussed) that such a broad definition of 'health care workers' identifies people who are exposed to categorically more respiratory infections than, say, elementary school teachers. Indeed, one of the studies was actually halted due to the H1N1 outbreak in 2009. So... of the people in the study who did get sick, we don't know how many of them caught it from their kids at home or on the bus to work when they weren't wearing . Interestingly, one of the two randomized studies they looked at, having by far with the largest number of participants (1669), concludes: > Continuous use of N95 respirators was more efficacious against CRI than intermittent use of N95 or medical masks. (The other study with 1441 participants concludes that N95 respirators are more effective in preventing multiple simultaneous infections.) https://www.ncbi.nlm.nih.gov/pubmed/23413265/ https://www.ncbi.nlm.nih.gov/pubmed/23413265/ https://www.ncbi.nlm.nih.gov/pubmed/24472436 https://www.ncbi.nlm.nih.gov/pubmed/24472436