With some recent studies coming out questioning the efficacy of masking, Scientific American has published an article titled ‘Masks Work, Distorting Science to Dispute the Evidence Doesn’t’. In the article, the authors discuss the flaws in recent reviews and studies criticising the use of masks.
One recent study that garnered much attention was the Cochrane review which assessed multiple randomised controlled trials. The author of the study concluded there is no evidence masks make any difference - a conclusion which drew the attention of the Cochrane Library’s editor-in-chief, who had to state the conclusion was not an accurate representation of what the review found.
The Cochrane review is not the first report to come to such a conclusion as RCTs (randomised controlled trials) have made similar claims in the past. For example, an RCT from late last year claimed that N95 respirators were no better than medical or surgical masks for healthcare workers.
The Scientific American article then goes on to discuss the flaws of RCTs. In medicine, there is a hierarchy of evidence in which different forms of evidence are given different weights. At the bottom, observational studies can be found. Above these, RCTs, and above these, systematic reviews of the RCTs - this is what the Cochrane review was. These systematic reviews compile a range of clinical trials to give more conclusive statements.
While common in medicine, these trials and reviews are rarely used in engineering and other fields because there are more accurate and precise ways to model data without the need for such trials.
This is the same with masks, respirators, and filtration. There is ample evidence they work, and we already know the answers to questions such as ‘Does a mask protect me from an aerosolised virus?’. While people may wear masks incorrectly and have limited protection, no randomised trial could conclude that masks don’t work.
There are standards for respiratory protection (such as NIOSH’s N, R and P classifications), which are backed by decades of evidence. Respiratory protection is trusted and effective in many industries, from mining to chemical processing.
There is no denying that masks do work. While the efficacy is impacted by a wide range of variables, no RCT or systematic review can prove otherwise because we have ample evidence of their effectiveness from decades of research.