This comment is deeply flawed, if not blatantly false, please read the following before you consider spreading this information again:

First off, social distancing is a risk mitigation strategy for droplet transmission. The idea is to provide sufficient distance between people and a cough or sneeze that a large fraction of the droplets settle before they could end up in someone's eyes/mouth/nose/next inhaled breath. Briefly invading someone's 2-3m bubble while accidentally bumping into them or walking past them really carries very little risk of exposure. It's more relevant to having a conversation with someone, particularly when indoors.

Whether or not aerosols play a major role in transmission remains to be seen, but we know that the virus can survive in aerosols for hours, and aerosols can remain suspended in the air for a very long time. (That's where N95's may become more relevant, but pathogens that have a dominant aerosol transmission are rare. Things like TB and measles behave that way. SARS-CoV-2 would probably have a high R0 if it were dominantly transmitted this way.)

Now, the statement "only N95 masks are effective to prevent transmission" is just false in several different ways:

First, when worn by healthcare workers, there is no significant difference between surgical masks and N95 respirators in preventing respiratory infections.[1][2] To quote the meta-analysis study[1]:

>"We identified 6 clinical studies (3 RCTs, 1 cohort study and 2 case–control studies) and 23 surrogate exposure studies. In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection (RCTs: odds ratio [OR] 0.89, 95% confidence interval [CI] 0.64–1.24; cohort study: OR 0.43, 95% CI 0.03–6.41; case–control studies: OR 0.91, 95% CI 0.25–3.36); (b) influenza-like illness (RCTs: OR 0.51, 95% CI 0.19–1.41); or (c) reported workplace absenteeism (RCT: OR 0.92, 95% CI 0.57–1.50). In the surrogate exposure studies, N95 respirators were associated with less filter penetration, less face-seal leakage and less total inward leakage under laboratory experimental conditions, compared with surgical masks."

Next, let's look specifically at surgical masks when worn by the public in the case of SARS-CoV-1 in the following study[3]:

>We also used this investigation to quantify the impact of behaviors (i.e., mask wearing, handwashing) that were promoted to reduce the risk for SARS. Wearing masks outside the home in a reference period corresponding to the 2 weeks before symptom onset for cases was significantly protective against clinical SARS. Supporting the validity of this finding, there was a dose-response effect: by multivariable analysis, persons who always wore masks had a 70% lower risk of being diagnosed with clinical SARS compared with those who never wore masks, and persons with intermittent mask use had a 60% lower risk. Many persons who wore masks in the community did not use N-95 or similar highly efficient filtration devices, which have been recommended for use in the hospital setting.

And finally, the above doesn't even address the fact that mask protections work BOTH WAYS. It has also been shown[4] that masks when worn by infected individuals help prevent the dissemination of infectious droplets and aerosols, and reduces the rate of viral shedding. To quote that study, specifically on placing surgical masks on the infected:
>"Overall, masks produced a 3.4 fold (95% CI 1.8 to 6.3) reduction in viral aerosol shedding."

Finally, there's evidence that even homemade improvised masks work surprisingly well! They perform only marginally worse than surgical masks in particle filtration tests.[5][6] (Remember how surgical masks, which perform worse than N95's in those same type of tests, showed no significant difference in their ability to prevent illness?) To quote the conclusion of study[6]:

>"Any type of general mask use is likely to decrease viral exposure and infection risk on a population level, in spite of imperfect fit and imperfect adherence, personal respirators providing most protection. Masks worn by patients may not offer as great a degree of protection against aerosol transmission."

TL;DR In short, if everyone in public wore masks, it would not only be definitively protective for the wearer, but for those around them as well.

[1](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4868605/)

[2](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779801/)

[3](https://wwwnc.cdc.gov/eid/article/10/2/03-0730_article)

[4](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3591312/)

[5](https://www.researchgate.net/publication/258525804_Testing_t...)

[6](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2440799/)