I know there are many studies I’ve missed. Please link to them in the comments.
Perhaps this might be useful to cut and paste into pro-mask posts and comments?
Some mask studies from the last fifty years:
(Neil Orr) Is a mask necessary in the operating theatre?:
“There was no increase in wound infections when masks were discarded in 1980; in fact there was a significant decrease”.
“It would appear that minimum contamination can best be achieved by not wearing a mask at all” and that wearing a mask during surgery “is a standard procedure that could be abandoned.”
Silence is recommended as a better health policy than masks.
Links for all bullet-pointed studies below can be found here:
Ritter et al., in 1975, found that “the wearing of a surgical face mask had no effect upon the overall operating room environmental contamination.”
Ha’eri and Wiley, in 1980, applied human albumin microspheres to the interior of surgical masks in 20 operations. At the end of each operation, wound washings were examined under the microscope. “Particle contamination of the wound was demonstrated in all experiments.”
Laslett and Sabin, in 1989, found that caps and masks were not necessary during cardiac catheterization. “No infections were found in any patient, regardless of whether a cap or mask was used,” they wrote. Sjøl and Kelbaek came to the same conclusion in 2002.
In Tunevall’s 1991 study, a general surgical team wore no masks in half of their surgeries for two years. After 1,537 operations performed with masks, the wound infection rate was 4.7%, while after 1,551 operations performed without masks, the wound infection rate was only 3.5%.
A review by Skinner and Sutton in 2001 concluded that “The evidence for discontinuing the use of surgical face masks would appear to be stronger than the evidence available to support their continued use.”
Lahme et al., in 2001, wrote that “surgical face masks worn by patients during regional anaesthesia, did not reduce the concentration of airborne bacteria over the operation field in our study. Thus they are dispensable.”
Figueiredo et al., in 2001, reported that in five years of doing peritoneal dialysis without masks, rates of peritonitis in their unit were no different than rates in hospitals where masks were worn.
Bahli did a systematic literature review in 2009 and found that “no significant difference in the incidence of postoperative wound infection was observed between masks groups and groups operated with no masks.”
Surgeons at the Karolinska Institute in Sweden, recognizing the lack of evidence supporting the use of masks, ceased requiring them in 2010 for anesthesiologists and other non-scrubbed personnel in the operating room. “Our decision to no longer require routine surgical masks for personnel not scrubbed for surgery is a departure from common practice. But the evidence to support this practice does not exist,” wrote Dr. Eva Sellden.
Webster et al., in 2010, reported on obstetric, gynecological, general, orthopaedic, breast and urological surgeries performed on 827 patients. All non-scrubbed staff wore masks in half the surgeries, and none of the non-scrubbed staff wore masks in half the surgeries. Surgical site infections occurred in 11.5% of the Mask group, and in only 9.0% of the No Mask group.
Lipp and Edwards reviewed the surgical literature in 2014 and found “no statistically significant difference in infection rates between the masked and unmasked group in any of the trials.” Vincent and Edwards updated this review in 2016 and the conclusion was the same.
Carøe, in a 2014 review based on four studies and 6,006 patients, wrote that “none of the four studies found a difference in the number of post-operative infections whether you used a surgical mask or not.”
Salassa and Swiontkowski, in 2014, investigated the necessity of scrubs, masks and head coverings in the operating room and concluded that “there is no evidence that these measures reduce the prevalence of surgical site infection.”
Da Zhou et al., reviewing the literature in 2015, concluded that “there is a lack of substantial evidence to support claims that facemasks protect either patient or surgeon from infectious contamination.”
A cluster randomised trial of cloth masks compared with medical masks in healthcare workers:
Results: The rates of all infection outcomes were highest in the cloth mask arm, with the rate of ILI statistically significantly higher in the cloth mask arm (relative risk (RR)=13.00, 95% CI 1.69 to 100.07) compared with the medical mask arm. Cloth masks also had significantly higher rates of ILI compared with the control arm. An analysis by mask use showed ILI (RR=6.64, 95% CI 1.45 to 28.65) and laboratory-confirmed virus (RR=1.72, 95% CI 1.01 to 2.94) were significantly higher in the cloth masks group compared with the medical masks group. Penetration of cloth masks by particles was almost 97% and medical masks 44%.
Conclusions: This study is the first RCT of cloth masks, and the results caution against the use of cloth masks. This is an important finding to inform occupational health and safety. Moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection. Further research is needed to inform the widespread use of cloth masks globally. However, as a precautionary measure, cloth masks should not be recommended for HCWs, particularly in high-risk situations, and guidelines need to be updated.
Adverse Effects of Prolonged Mask Use among Healthcare Professionals during COVID-19:
A total of 343 healthcare professionals on the COVID-19 front lines participated in this study. The majority were female (n = 315) and 227 were located in New York City. 225 respondents identified as White, 34 as Hispanic, 23 as African American, and 61 as “other” ethnicity. 314 respondents reported adverse effects from prolonged mask use with headaches being the most common complaint (n = 245). Skin breakdown was experienced by 175 respondents, and acne was reported in 182 respondents. Impaired cognition was reported in 81 respondents. Previous history of headaches (n = 98), skin sensitivity (n = 164), and acne (n = 121) were found in some respondents. Some respondents experienced resolved side effects once masks were removed, while others required physical or medical intervention
Prolonged use of N95 and surgical masks by healthcare professionals during COVID-19 has caused adverse effects such as headaches, rash, acne, skin breakdown, and impaired cognition in the majority of those surveyed. As a second wave of COVID-19 is expected, and in preparation for future pandemics, it is imperative to identify solutions to manage these adverse effects. Frequent breaks, improved hydration and rest, skin care, and potentially newly designed comfortable masks are recommendations for future management of adverse effects related to prolonged mask use.
Effects of surgical and FFP2/N95 face masks on cardiopulmonary exercise capacity:
Results: The pulmonary function parameters were significantly lower with mask (forced expiratory volume: 5.6 ± 1.0 vs 5.3 ± 0.8 vs 6.1 ± 1.0 l/s with sm, ffpm and nm, respectively; p = 0.001; peak expiratory flow: 8.7 ± 1.4 vs 7.5 ± 1.1 vs 9.7 ± 1.6 l/s; p < 0.001). The maximum power was 269 ± 45, 263 ± 42 and 277 ± 46 W with sm, ffpm and nm, respectively; p = 0.002; the ventilation was significantly reduced with both face masks (131 ± 28 vs 114 ± 23 vs 99 ± 19 l/m; p < 0.001). Peak blood lactate response was reduced with mask. Cardiac output was similar with and without mask. Participants reported consistent and marked discomfort wearing the masks, especially ffpm
Conclusion: Ventilation, cardiopulmonary exercise capacity and comfort are reduced by surgical masks and highly impaired by FFP2/N95 face masks in healthy individuals. These data are important for recommendations on wearing face masks at work or during physical exercise.
Visualizing droplet dispersal for face shields and masks with exhalation valves:
“To summarize, we have examined the effectiveness of face shields and masks equipped with exhalation ports in mitigating the spread of exhaled respiratory droplets. The aim of the qualitative visualizations presented here is to help increase public awareness regarding the effectiveness of these alternatives to regular masks. We observe that face shields are able to block the initial forward motion of the exhaled jet; however, aerosolized droplets expelled with the jet are able to move around the visor with relative ease.
Over time, these droplets can disperse over a wide area in both the lateral and longitudinal directions, albeit with decreasing droplet concentration. We have also compared droplet dispersal from a regular N95-rated face mask to one equipped with an exhale valve. As expected, the exhalation port significantly reduces the effectiveness of the mask as a means of source control, as a large number of droplets pass through the valve unfiltered. Notably, shields impede the forward motion of the exhaled droplets to some extent, and masks with valves do so to an even lesser extent. However, once released into the environment, the aerosol-sized droplets get dispersed widely depending on light ambient disturbances.
Overall, the visuals presented here indicate that face shields and masks with exhale valves may not be as effective as regular face masks in restricting the spread of aerosolized droplets. Thus, despite the increased comfort that these alternatives offer, it may be preferable to use well-constructed plain masks. There is a possibility that widespread public adoption of the alternatives, in lieu of regular masks, could have an adverse effect on ongoing mitigation efforts against COVID-19.”
Some expert commentary:
“How can a person be forced by any business or government entity to wear a mask (which affects the respiratory system) without having a physical exam by a licensed doctor who approves such an action?” ~ Peggy Hall
Science Says Healthy People Should Not Wear Masks
Masks reduce intake of oxygen, leading to carbon dioxide toxicity
Germs are trapped near your mouth and nose, increasing risk of infection
Wearing a mask causes you to touch your face more frequently
There is no scientific evidence that supports healthy people wearing masks
Masks obscure your facial features and impede normal social interaction
Masks make it hard for hearing-impaired people to understand you
Masks symbolize suppression of speech
MASKS DO NOT PREVENT SPREAD OF VIRUS
NOTE: Many links are being scrubbed (removed) from the Internet. We are updating as possible.
(1) New England Journal of Medicine:
“We know that wearing a mask outside health care facilities offers little, if any, protection from infection.”
(2) CAL-OSHA Regulations:”Cloth face coverings do not protect against COVD -19”
(3) California Department of Health:”Face coverings may increase risk if users reduce their use of strong defenses.”
“There is limited evidence to suggest that use of cloth face coverings by the public during a pandemic could help reduce disease transmission.”
(4) FDA – “Even a properly fitted N95 mask does not prevent illness or death”
(5) CDC — There is no scientific evidence for healthy people wearing masks:
(6) Neurosurgeon Dr. Russell Blaylock :”There is no scientific evidence that masks are effective. If you are not sick, you should not wear a face mask.”
(7) Columbia University: Psychological Harms of Face Masks:”Many young children burst into tears or recoil when someone wearing a mask approaches. By putting on masks, we take away information that makes it especially difficult for children to recognize others and read emotional signals, which is unsettling and disconcerting.”
(8) US Surgeon General Jerome Adams:”Masks are not effective in preventing the general public from catching coronavirus.”
(9) Dr. Anthony Fauci: “People should not be walking around wearing masks. Masks do not provide the protection people think they do.”
(10) WHO, Dr. Mike Ryan:”There is no specific evidence to suggest that the wearing of masks by the mass population has any potential benefit. In fact, there’s some evidence to suggest the opposite in the misuse of wearing a mask properly or fitting it properly.
(11) US Department of Labor — OSHA:”Oxygen deficient is any atmosphere that contains less than 19.5%.” This happens when the oxygen is displaced by inert gas such as CARBON DIOXIDE and is the leading cause of FATALITIES.”