“We know that wearing a mask outside health care facilities offers little, if any, protection from infection.” New England Journal of Medicine. Here is the technical journal article.
In another paper (link below), less technically worded:
Summary / Abstract Masks
and respirators do not work. There have been extensive randomized controlled trial (RCT) studies, and meta-analysis reviews of RCT studies, which all show that masks and respirators do not work to prevent respiratory influenza-like illnesses, or respiratory illnesses believed to be transmitted by droplets and aerosol particles.
Furthermore, the relevant known physics and biology, which I review, are such that masks and respirators should not work. It would be a paradox if masks and respirators worked, given what we know about viral respiratory diseases: The main transmission path is long-residence-time aerosol particles (< 2.5 μm), which are too fine to be blocked, and the minimum-infective-dose is smaller than one aerosol particle.
The present paper about masks illustrates the degree to which governments, the mainstream media, and institutional propagandists can decide to operate in a science vacuum, or select only incomplete science that serves their interests. Such recklessness is also certainly the case with the current global lockdown of over 1 billion people, an unprecedented experiment in medical and political history.
(1) (PDF) Masks Don’t Work: A review of science relevant to COVID-19 social policy. Available from: https://www.researchgate.net/publication/340570735_Masks_Don’t_Work_A_review_of_science_relevant_to_COVID-19_social_policy [accessed May 30 2020].