I have personally been unable to find a single reliable study of mask efficiency, and the ones about N95 respirator efficiency that I found had the grim conclusion that they don't help much unless expertly fitted, and even health professional aren't very good to fitting them properly.
What I have found are some simulations that make unrealistic assumptions and reach the pre-supposed conclusions.
> Mask catches big droplets but is not effective catching small particles.
Well, then it's all a question of virion size vs mask hole size, then, and how long virions are still active, and what the effect of breath diffusion is. Of which the raw numbers would say that masks are mostly useless. I have not yet seen a model/study/trial that addresses this properly.
I wear an N95, and I encourage everyone else to do the same, but I do recognize that it's not a "fact"
The purpose and design of surgical masks is to protect others, not the wearer. Mask catches big droplets but is not effective catching small particles. It's hard to wear tightly.
Respirator is designed to protect wearer. Buy N95 respirator and wear it correctly (trim your beard if necessary) if you want to be safe.
A respirator with an exhalation valve, protects the wearer but does not give as good protection to others as respirator without a valve.