In a recent Lancet article the author notes (see Fennelly, Particle sizes of infectious aerosols: implications for infection control, Lancet, 24 July, 2020) :
Surgical masks might offer some respiratory protection from inhalation of infectious aerosols, but not as much as respirators. However, surgical masks worn by patients reduce exposures to infectious aerosols to health-care workers and other individuals. The variability of infectious aerosol production, with some socalled super-emitters producing much higher amounts of infectious aerosol than most, might help to explain the epidemiology of super-spreading. Airborne infection control measures are indicated for potentially lethal respiratory pathogens such as severe acute respiratory syndrome coronavirus ... Modelling studies and simulated workplace protection studies in the USA have shown benefits of various types of respirators and little to no protection from surgical masks. A study in the UK found that surgical masks could reduce inert aerosol exposure by two times, but filtering facepiece respirators reduced the exposure by a factor of 100 or higher. In a study of influenza aerosols, surgical masks reduced exposure by an average of six times, but there was a wide range of reduction from 1·1 to 55 times, depending on the design of the mask. Two randomised trials did not show any benefit of N95 respirators over surgical masks in reducing respiratory illnesses, and two showed that the respirators were protective. However, none of the trials used quantitative fit testing, and two had surprisingly low failure rates (1·1–2·6%) compared with 60% found in a panel study for the same N95 respirators. The low failure rates suggest a problem ith fit testing.
Overall we still have a "on the one hand and on the other hand". It seems that there is a class of people who vehemently refuse any advice and do not care.
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