The Evidence Regarding Masks
Of all of the studies regarding face masks currently cited by various Governments, Health Agencies and media outlets:
1. not one study they attempt to cite has "healthy people/populations" as a control group
2. there are no peer reviewed studies for "healthy people/populations" wearing masks
3. there are no studies which have masks as the only form of source control (usually mixed with hand washing, sanitizer or distancing)
4. many of the references have no relevance to the actual study
5. a majority of the above studies are based on anecdotal observations.
There is no reliable or policy-grade evidence that face masks can reduce the risk from COVID-19.
What about the negative effects or studies which show "no statistical difference" or actual studies which cite "statistical significance " or "clinical relevance"?
March 31,2021 - "Is a Mask That Covers the Mouth and Nose Free from Undesirable Side Effects in Everyday Use and Free of Potential Hazards?
Many countries introduced the requirement to wear masks in public spaces for containing SARS-CoV-2 making it commonplace in 2020. Up until now, there has been no comprehensive investigation as to the adverse health effects masks can cause. The aim was to find, test, evaluate and compile scientifically proven related side effects of wearing masks. For a quantitative evaluation, 44 mostly experimental studies were referenced, and for a substantive evaluation, 65 publications were found. The literature revealed relevant adverse effects of masks in numerous disciplines. In this paper, we refer to the psychological and physical deterioration as well as multiple symptoms described because of their consistent, recurrent and uniform presentation from different disciplines as a Mask-Induced Exhaustion Syndrome (MIES). We objectified evaluation evidenced changes in respiratory physiology of mask wearers with significant correlation of O2 drop and fatigue (p < 0.05), a clustered co-occurrence of respiratory impairment and O2 drop (67%), N95 mask and CO2 rise (82%), N95 mask and O2 drop (72%), N95 mask and headache (60%), respiratory impairment and temperature rise (88%), but also temperature rise and moisture (100%) under the masks. Extended mask-wearing by the general population could lead to relevant effects and consequences in many medical fields."
Feb 11, 2021 - "Masks Can Be Detrimental to Babies' Speech and Language Development". David J. Lewkowic. Scientific American. Cogntion, (Opinion)
"…the COVID pandemic has laid bare our fundamental need to see whole faces. Could it be that babies and young children, who must learn the meaning of the myriad communicative signals normally available in their social partners’ faces, are especially vulnerable to their degradation in partially visible faces? … in my lab … We discovered that babies begin lip- reading at around 8 months of age. …
Crucially, once lip-reading emerges in infancy, it becomes the default mode of speech processing whenever comprehension is difficult. …
Overall, the research to date demonstrates that the visible articulations that babies normally see when others are talking play a key role in their acquisition of communication skills. Research also shows that babies who lip-read more have better language skills when they’re older. If so, this suggests that masks probably hinder babies’ acquisition of speech and language.”
January 5, 2021 - Corona children studies "Co-Ki": First results of a Germany-wide registry on mouth and nose covering (mask) in children
Background: Narratives about complaints in children and adolescents caused by wearing a mask are accumulating. There is, to date, no registry for side effects of masks.
Methods: At the University of Witten/Herdecke an online registry has been set up where parents, doctors, pedagogues and others can enter their observations. On 20.10.2020, 363 doctors were asked to make entries and to make parents and teachers aware of the registry.
Results: By 26.10.2020 the registry had been used by 20,353 people. In this publication we report the results from the parents, who entered data on a total of 25,930 children. The average wearing time of the mask was 270 minutes per day. Impairments caused by wearing the mask were reported by 68% of the parents. These included irritability (60%), headache (53%), difficulty concentrating (50%), less happiness (49%), reluctance to go to school/kindergarten
(44%), malaise (42%) impaired learning (38%) and drowsiness or fatigue (37%).
Discussion: This world's first registry for recording the effects of wearing masks in children is dedicated to a new research question. Bias with respect to preferential documentation of children who are particularly severely affected or who are fundamentally critical of protective measures cannot be dismissed. The frequency of the registry’s use and the spectrum of symptoms registry indicate the importance of the topic and call for representative surveys,
randomized controlled trials with various masks and a renewed risk-benefit assessment for the vulnerable group of children: adults need to collectively reflect the circumstances under which they would be willing to take a residual risk upon themselves in favor of enabling children to have a higher quality of life without having to wear a mask.”
December 31, 2020 - "The intersection of COVID‐19, school, and headaches: Problems and solutions" Headache: The Journal of Head and Face Pain, 61: 190-201
"Many common triggers such as dehydration, fasting, sleep problems, and stressors were discussed above. Here we highlight screen use and mask wearing as potential additional school‐related triggers.mm ,,, Pressure created by the mask or its straps against various contact points on the face or scalp could trigger headache"
Nov 22, 2020 - Facemasks in the COVID-19 era: A health hypothesis
“Abstract: … Although, scientific evidence supporting facemasks’ efficacy is lacking, adverse physiological, psychological and health effects are established. Is has been hypothesized that facemasks have
compromised safety and efficacy profile and should be avoided from use. The current article comprehensively summarizes scientific evidences with respect to wearing facemasks in the COVID-19 era. …
Long-Term health consequences of wearing facemasks: Long-term practice of wearing facemasks has strong potential for devastating health consequences. Prolonged hypoxic-hypercapnic state compromises normal physiological and psychological balance, deteriorating health and promotes the developing and progression of
existing chronic diseases (10 refs).
Conclusion: … Wearing facemasks has been demonstrated to have substantial adverse physiological and psychological effects. These include hypoxia, hypercapnia, shortness of breath, increased acidity and toxicity, activation of fear and stress response, rise in stress hormones, immunosuppression, fatigue, headaches, decline in cognitive performance, predisposition for viral and infectious illnesses, chronic stress, anxiety and depression. Long-term consequences of wearing facemask can cause health deterioration, developing and progression of chronic diseases and premature death."
Nov 18, 2020 - "Effectiveness of Adding a Mask Recommendation to Other Public Health Measures to Prevent SARS-CoV-2 Infection in Danish Mask Wearers
"the trial found no statistically significant benefit of wearing a face mask. The study used “high-quality surgical masks with a filtration rate of 98%”.
November 2020 - “Masks, false safety and real dangers, Part 2: Microbial challenges from masks”. Primary Doctor Medical Journal.
In November 2020, Borovoy et al.  published an extensive review of biological and medical knowledge that allowed them to infer a large potential for significant harms from masking, via microbial challenges from the masks. They rightly stress the known yet underplayed role of bacteria in viral pandemics, and also review respiratory diseases arising from oral bacteria, which can be induced by mask wearing to penetrate and
infect the respiratory tract and lungs.
October 29, 2020 - "The implications of face masks for babies and families during the COVID-19 pandemic: A discussion paper"
“Abstract: … COVID-19 has changed the way that newborn babies are cared for within the neonatal setting due to the introduction of social distancing and wearing of face masks to limit the spread of the infection. Potential implications exist related to the normal development of bonding and connections with others. This paper discusses the importance of face to face interactions for early attachment between babies and parents within the context of relevant underpinning developmental theory. …”
Dr. Margarite Griesz-Brisson MD, PhD is a Consultant Neurologist and Neurophysiologist with a PhD in Pharmacology, with special interest in neurotoxicology, environmental medicine, neuroregeneration and neuroplasticity. This is what she has to say about facemasks and their effects on our brains:
"The reinhalation of our exhaled air will without a doubt create oxygen deficiency and a flooding of carbon dioxide. We know that the human brain is very sensitive to oxygen deprivation. There are nerve cells for example in the hippocampus that can't be longer than 3 minutes without oxygen - they cannot survive.... However, when you have chronic oxygen deprivation, all of those symptoms disappear, because you get used to it. But your efficiency will remain impaired and the under-supply of oxygen in your brain continues to progress.... While you're thinking that you have gotten used to wearing your mask and rebreathing your own exhaled air, the degenerative processes in your brain are getting amplified as your oxygen deprivation continues.
The second problem is that the nerve cells in your brain are unable to divide themselves normally. So in case our governments will generously allow as to get rid of the masks and go back to breathing oxygen freely again in a few months, the lost nerve cells will no longer be regenerated. What is gone is gone. The acute warning symptoms are headaches, drowsiness, dizziness, issues in concentration, slowing down of reaction time - reactions of the cognitive system...
There is no unfounded medical exemption from face masks because oxygen deprivation is dangerous for every single brain. It must be the free decision of every human being whether they want to wear a mask that is absolutely ineffective to protect themselves from a virus.
For children and adolescents, masks are an absolute no-no. Children and adolescents have an extremely active and adaptive immune system and they need a constant interaction with the microbiome of the Earth. Their brain is also incredibly active, as it is has so much to learn. The child's brain, or the youth's brain, is thirsting for oxygen. The more metabolically active the organ is, the more oxygen it requires. In children and adolescents every organ is metabolically active.
To deprive a child's or an adolescent's brain from oxygen, or to restrict it in any way, is not only dangerous to their health, it is absolutely criminal. Oxygen deficiency inhibits the development of the brain, and the damage that has taken place as a result CANNOT be reversed.
The child needs the brain to learn, and the brain needs oxygen to function. We don't need a clinical study for that. This is simple, indisputable physiology. Consciously and purposely induced oxygen deficiency is an absolutely deliberate health hazard, and an absolute medical contraindication.
An absolute medical contraindication in medicine means that this drug, this therapy, this method or measure should not be used, and is not allowed to be used. To coerce an entire population to use an absolute medical contraindication by force, there must be definite and serious reasons for this, and the reasons must be presented to competent interdisciplinary and independent bodies to be verified and authorised.
I know how damaging oxygen deprivation is for the brain, cardiologists know how damaging it is for the heart, pulmonologists know how damaging it is for the lungs. Oxygen deprivation damages every single organ.
Where are our health departments, our health insurance, our medical associations? It would have been their duty to be vehemently against the lockdown and to stop it and stop it from the very beginning.
Why do the medical boards issue punishments to doctors who give people exemptions? Does the person or the doctor seriously have to prove that oxygen deprivation harms people? What kind of medicine are our doctors and medical associations representing?
August 12, 2020 - Face masks: benefits and risks during the COVID-19 crisis
“If masks are not exchanged regularly (or washed properly when made of cloth), pathogens can accumulate in the mask. When improperly used, the risk of spreading the pathogen— including SARS-CoV-2—might be critically increased.” (p. 5)
August 6, 2020 - "Masked education? The benefits and burdens of wearing face masks in schools during the current Corona pandemic. Trends in Neuroscience and Education.
“Abstract: … covering the lower half of the face reduces the ability to communicate, interpret, and mimic the expressions of those with whom we interact. Positive emotions become less recognizable, and negative emotions are amplified. Emotional mimicry, contagion, and emotionality in general are reduced and (thereby) bonding between teachers and learners, group cohesion, and learning – of which emotions are a major driver.
1. Introduction: … along with other measures of physical distancing and economic lockdowns, school closures were implemented during March 2020 affecting more than 1.5 billion students (children and adolescents) around the globe (ref). These closures of schools lasted for a few weeks only (as in Denmark) up to several months (in Italy and many other countries; (ref)) and led to marked decreases in educational gains (ref), hunger (because school meals were no longer served), increases in child abuse (because children were no longer observed by school staff), and, in general, the risk of “scarring the life chances of a generation of young people”(ref) (because of the long-term psychological, physiological, educational and even economic burden (ref), that societies put on their most vulnerable members; (ref))…
• … wearing masks may have physical side effects.
• Face masks impair face recognition and face identification.
• Face masks impair verbal and non-verbal communication.
• Face masks block emotional signalling between teacher and learner.
Given these pros and cons, it is not clear whether face masks should play a major role in educational settings in times of the current viral pandemic. … This matter should be discussed urgently, since it globally affects more than 1.5 billion students, teachers, and school staff directly, and, in addition, their families indirectly.
6. Face masks block emotional signalling between teachers and students: … In sum, recognition of, and response to, the outward emotional displays of one's peers’ faces is a critical and necessary component of social interaction in schools. It helps pupils and teachers to modify their behavior in order to align with social communication and behavioral norms. When these emotional displays are inhibited by face masks, our ability to communicate effectively with one another is reduced and we are primarily left with mimicking negative (frown) emotions. All of this
happens primarily outside of conscious awareness, and hence, is hard to be consciously controlled or even corrected. Since emotions are a major driver of group cohesion, the decreased emotionality, and decreased positive emotionality in particular, may interfere with smooth classroom action. Given the fact that the very process of learning is facilitated by emotions (this is their main raison d´être), face masks are likely to cause some interference with pedagogy.” Coleen Huber
"July 6, 2020 - 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.
July 6, 2020 - Masks are neither effective nor safe: A summary of the science
In this meta-analysis, face masks were found to have no detectable effect against transmission of viral infections. (1) It found: “Compared to no masks, there was no reduction of influenza-like illness cases or influenza for masks in the general population, nor in healthcare workers.”
This 2020 meta-analysis found that evidence from randomized controlled trials of face masks did not support a substantial effect on transmission of laboratory-confirmed influenza, either when worn by infected persons (source control) or by persons in the general community to reduce their susceptibility. (2)
Another recent review found that masks had no effect specifically against Covid-19, although facemask use seemed linked to, in 3 of 31 studies, “very slightly reduced” odds of developing influenza-like illness. (3)
This 2019 study of 2862 participants showed that both N95 respirators and surgical masks “resulted in no significant difference in the incidence of laboratory confirmed influenza." (4)
This 2016 meta-analysis found that both randomized controlled trials and observational studies of N95 respirators and surgical masks used by healthcare workers did not show benefit against transmission of acute respiratory infections. It was also found that acute respiratory infection transmission “may have occurred via contamination of provided respiratory protective equipment during storage and reuse of masks and respirators throughout the workday.” (5)
A 2011 meta-analysis of 17 studies regarding masks and effect on transmission of influenza found that “none of the studies established a conclusive relationship between mask/respirator use and protection against influenza infection.” (6) However, authors speculated that effectiveness of masks may be linked to early, consistent and correct usage.
Face mask use was likewise found to be not protective against the common cold, compared to controls without face masks among healthcare workers. (7)"
June 19, 2020 - Downsides of face masks and possible mitigation strategies: a systematic review and meta-analysis
“There are insufficient data to quantify all of the adverse effects that might reduce the acceptability, adherence, and effectiveness of face masks. New research on facemasks should assess and report the harms and downsides. Urgent research is also needed on methods and designs to mitigate the downsides of facemask wearing, particularly the
assessment of alternatives such as face shields.”
June 18, 2020 - Can the Elastic of Surgical Face Masks Stimulate Ear Protrusion in Children? (Letter to the Editor)
“Abstract: … Among those on the market, surgical masks with elastic loops are the ones most chosen by parents for their children. These elastics cause constant compression on the skin and, consequently, on the cartilage of the auricle, leading to erythematous and painful lesions of the retroauricular skin when the masks are used for many hours a day. Pre- adolescent children have undeveloped auricular cartilage with less resistance to deformation; prolonged pressure from the elastic loops of the mask at the hollow or, even worse, at the anthelix level can influence the correct growth and angulation of the outer ear. In fact, unlike when using conservative methods for the treatment of protruding ears, this prolonged pressure can increase the cephaloauricular angle of the outer auricle. It is important for the authorities supplying the masks to be aware of this potential risk and for alternative solutions to be found …”
June 2020 - “Exercise with facemask; Are we handling a devil's sword?” – A physiological hypothesis
"Straying away from a sedentary lifestyle is essential, especially in these troubled times of a global pandemic to reverse the ill effects associated with the health risks as mentioned earlier. In the view of anticipated effects on immune system and prevention against influenza and Covid-19, globally moderate to vigorous exercises are advocated wearing protective equipment such as facemasks. Though WHO supports facemasks only for Covid-19 patients, healthy “social exercisers” too exercise strenuously with customized facemasks or N95 which hypothesized to pose more significant health risks and tax various physiological systems especially pulmonary, circulatory and immune systems. Exercising with facemasks may reduce available Oxygen and increase air trapping preventing substantial carbon dioxide exchange. The hypercapnic hypoxia may potentially increase acidic environment, cardiac overload, anaerobic metabolism and renal overload, which may substantially aggravate the underlying pathology of established chronic diseases. Further contrary to the earlier thought, no evidence exists to claim the facemasks during exercise offer additional protection from the droplet transfer of the virus. Hence, we recommend social distancing is better than facemasks during exercise and optimal utilization rather than exploitation of facemasks during exercise."
MAY 8th 2020 - From the CDC itself which also follows the WHOs guidelines..
"If you are sick wear a cloth covering over your nose and mouth. You should wear a cloth face covering, over your nose and mouth if you must be around other people or animals, including pets (even at home). You don’t need to wear the cloth face covering if you are alone. If you can’t put on a cloth face covering (because of trouble breathing, for example), cover your coughs and sneezes in some other way. Try to stay at least 6 feet away from other people. This will help protect the people around you. Cloth face coverings should not be placed on young children under age 2 years, anyone who has trouble breathing, or anyone who is not able to remove the covering without help."
April 2020 "The authors and CIDRAP have received requests in recent weeks to remove this article from the CIDRAP website.
Reasons have included: (1) we don’t truly know that cloth masks (face coverings) are not effective, since the data are so limited, (2) wearing a cloth mask or face covering is better than doing nothing, (3) the article is being used by individuals and groups to support non-mask wearing where mandated and (4) there are now many modeling studies suggesting that cloth masks or face coverings could be effective at flattening the curve and preventing many cases of infection.
We do, however, have data from laboratory studies that indicate cloth masks or face coverings offer very low filter collection efficiency for the smaller inhalable particles we believe are largely responsible for transmission
The guidelines from the Centers for Disease Control and Prevention (CDC) for face coverings initially did not have any citations for studies of cloth material efficiency or fit, but some references have been added since the guidelines were first posted. We reviewed these and found that many employ very crude, non-standardized methods (Anfinrud 2020, Davies 2013, Konda 2020, Aydin 2020, Ma 2020) or are not relevant to cloth face coverings because they evaluate respirators or surgical masks (Leung 2020, Johnson 2009, Green 2012).
The CDC failed to reference the National Academies of Sciences Rapid Expert Consultation on the Effectiveness of Fabric Masks for the COVID-19 Pandemic (NAS 2020), which concludes, “The evidence from…laboratory filtration studies suggests that such fabric masks may reduce the transmission of larger respiratory droplets. There is little evidence regarding the transmission of small aerosolized particulates of the size potentially exhaled by asymptomatic or presymptomatic individuals with COVID-19.
Is wearing a face covering better than nothing?
Wearing a cloth mask or face covering could be better than doing nothing, but we simply don’t know at this point. We have observed an evolution in the messaging around cloth masks, from an initial understanding that they should not be seen as a replacement for physical distancing to more recent messaging that suggests cloth masks are equivalent to physical distancing. And while everyone appears to understand that this messaging suggests that a cloth mask is appropriate only for source control (ie, to protect others from infection), recent CDC and other guidance recommending their use by workers seems to imply that they offer some type of personal protection.
We know of workplaces in which employees are told they cannot wear respirators for the hazardous environments they work in, but instead need to wear a cloth mask or face covering. These are dangerous and inappropriate applications that greatly exceed the initial purpose of a cloth mask. We are concerned that many people do not understand the very limited degree of protection a cloth mask or face covering likely offers as source control for people located nearby.
We know of workplaces in which employees are told they cannot wear respirators for the hazardous environments they work in, but instead need to wear a cloth mask or face covering. These are dangerous and inappropriate applications that greatly exceed the initial purpose of a cloth mask. We are concerned that many people do not understand the very limited degree of protection a cloth mask or face covering likely offers as source control for people located nearby."
Apr 2020 - Effectiveness of Surgical and Cotton Masks in Blocking SARS–CoV-2: A Controlled Comparison in 4 Patients.. This article has been retracted. See Notice of Retraction.
"Whether face masks worn by patients with coronavirus disease 2019 (COVID-19) prevent contamination of the environment is uncertain (2, 3)
Objective: To evaluate the effectiveness of surgical and cotton masks in filtering SARS–CoV-2.
We compared disposable surgical masks (180 mm × 90 mm, 3 layers [inner surface mixed with polypropylene and polyethylene, polypropylene filter, and polypropylene outer surface], pleated, bulk packaged in cardboard; KM Dental Mask, KM Healthcare Corp) with reusable 100% cotton masks (160 mm × 135 mm, 2 layers, individually packaged in plastic; Seoulsa).
A petri dish... was placed approximately 20 cm from the patients' mouths. Patients were instructed to cough 5 times each onto a petri dish while wearing the following sequence of masks: no mask, surgical mask, cotton mask, and again with no mask.
All swabs from the outer mask surfaces of the masks were positive for SARS–CoV-2, whereas most swabs from the inner mask surfaces were negative" (no virus on the inside but lots on the outside from adjusting, touching, hanging on your rear view)
"Discussion: Neither surgical nor cotton masks effectively filtered SARS–CoV-2 during coughs by infected patients."
The consistent finding of virus on the outer mask surface is unlikely to have been caused by experimental error or artifact.
A turbulent jet due to air leakage around the mask edge could contaminate the outer surface." Basically the mask has to be fitted perfectly, otherwise, it will leak..
In conclusion, both surgical and cotton masks seem to be ineffective in preventing the dissemination of SARS–CoV-2 from the coughs of patients with COVID-19 to the environment and external mask surface."
The retraction on this was very questionable when you read it..
"LOD of the in-house reverse transcriptase polymerase chain reaction used in the study (2.63 log copies/mL), and we regret our failure to express the values below LOD as “<LOD (value).”
May19, 2020 from CDC - Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings—Personal Protective and Environmental Measures
"Although mechanistic studies support the potential effect of hand hygiene or face masks, evidence from 14 randomized controlled trials of these measures did not support a substantial effect on transmission of laboratory-confirmed influenza.
In pooled analysis, we found no significant reduction in influenza transmission with the use of face masks....
....None of the household studies reported a significant reduction in secondary laboratory-confirmed influenza virus infections in the face mask group (11–13,15,17,34,35)
There is limited evidence for their effectiveness in preventing influenza virus transmission either when worn by the infected person for source control or when worn by uninfected persons to reduce exposure. Our systematic review found no significant effect of face masks on transmission of laboratory-confirmed influenza.
We did not find evidence that surgical-type face masks are effective in reducing laboratory-confirmed influenza transmission, either when worn by infected persons (source control) or by persons in the general community to reduce their susceptibility (Figure 2)."
Moreover, why did the CDC choose to leave this out of their "research" or evidence?
(April 2020).. skip to chapter 16 if you like or read the whole thing.
"There are no studies of individuals wearing homemade fabric masks in the course of their typical activities. Therefore, we have only limited, indirect evidence regarding the effectiveness of such masks for protecting others, when made and worn by the general public on a regular basis. That evidence comes primarily from laboratory studies testing the effectiveness of different materials at capturing particles of different sizes.
The evidence from these laboratory filtration studies suggests that such fabric masks may reduce the transmission of larger respiratory droplets. There is little evidence regarding the transmission of small aerosolized particulates of the size potentially exhaled by asymptomatic or presymptomatic individuals with COVID-19."
Note the word "may" but they simply don't know at this point.. But the evidence doesn't support the narrative.. Weird..
Feb 3, 2020. Effectiveness of N95 respirators versus surgical masks against influenza: A systematic review and meta-analysis
Results: A total of six RCTs involving 9 171 participants were included. There were no statistically significant differences in preventing laboratory-confirmed influenza (RR = 1.09, 95% CI 0.92-1.28, P > .05), laboratory-confirmed respiratory viral infections (RR = 0.89, 95% CI 0.70-1.11),
laboratory-confirmed respiratory infection (RR = 0.74, 95% CI 0.42-1.29) and influenza-like illness (RR = 0.61, 95% CI 0.33-1.14) using N95 respirators and surgical masks. Meta-analysis indicated a protective effect of N95 respirators against laboratory-confirmed bacterial colonization (RR = 0.58, 95% CI 0.43-0.78).
Conclusion: The use of N95 respirators compared with surgical masks is not associated with a lower risk of laboratory-confirmed influenza. It suggests that N95 respirators should not be recommended for general public and non-high-risk medical staff those are not in close contact with influenza patients or suspected patients
Feb 2020 - The World Health Organization stated that viral transmission from asymptomatic people was likely "rare", based on information available at the time.
"Asymptomatic infection may be rare, and transmission from an asymptomatic person is very rare with other coronaviruses, as we have seen with Middle East Respiratory Syndrome coronavirus.Thus, transmission from asymptomatic cases is likely not a major driver of transmission.Persons who are symptomatic will spread the virus more readily through coughing and sneezing"
Sept 2019 - N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel A Randomized Clinical Trial Findings -
In this pragmatic, cluster randomized clinical trial involving 2862 health care personnel, there was no significant difference in the incidence of laboratory-confirmed influenza among health care personnel with the use of N95 respirators (8.2%) vs medical masks (7.2%).
June 2019 - Optical microscopic study of surface morphology and filtering efficiency of face masks.
" The PM10 filtering efficiency of four of the selected masks ranged from 63% to 84%. The poor filtering efficiency may have arisen from larger and open pores present in the masks. Interestingly, we found that efficiency dropped by 20% after the 4th washing and drying cycle."
Basically, after 4 washes the cloth masks are once again useless..
MARCH 2018 - Effect of a surgical mask on six minute walking distance
"Introduction: Six minutes walking test (6MWT) is regularly used in pulmonology. To minimize the risk of cross-infection, some patients must wear surgical mask at rest and sometimes during exercise.
Results: Distance was not modified by the mask (P=0.99). Dyspnea variation was significantly higher with surgical mask (+5.6 vs. +4.6; P<0.001) and the difference was clinically relevant. No difference was found for the variation of other parameters.
Conclusion: Wearing a surgical mask modifies significantly and clinically dyspnea without influencing walked distance.
May 2016 - “The surgical mask is a bad fit for risk reduction” (perspective)
“I propose that the surgical mask is a symbol that protects from the perception of risk by offering nonprotection to the public while causing behaviours that project risk into the future … In an annex to the Canadian pandemic influenza preparedness plan covering public health measures, the Public Health Agency of Canada (PHAC) does not recommend the use of masks by well individuals in pandemic situations, acknowledging that the mask has not been shown to be effective in such circumstances … The same annex on public health measures refers to the “false sense of security” that a mask can psychologically provide, but the converse is the real risk posed to a government unable to mollify its population.”
Nov 2014 Effects of long-duration wearing of N95 respirator and surgical facemask: a pilot study
Feb 2014 - Disposable surgical face masks for preventing surgical wound infection in clean surgery
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.
June 2014 - Dubious effect of surgical masks during surgery.
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.”
November 8, 2012 - “Need Satisfaction and Well-Being: Testing Self-Determination Theory in Eight Cultures”. Journal of Cross-Cultural Psychology.
"Self-Determination Theory (SDT) proposes that certain evolved psychological needs must be satisfied if individuals are to develop to their fullest potential, in the same way that plants require key nutrients to thrive (refs). SDT posits three universal needs: autonomy, competence, and relatedness. Autonomy involves the need to experience one’s
behavior as freely chosen and volitional, rather than imposed by external forces. Competence involves the need to feel capable and effective in one’s actions. Relatedness involves the need for belonging, intimacy, and connectedness to others. SDT theorists view these needs as broad motivational tendencies that operate across life domains and contend that satisfaction of all three needs, not just one or two, is essential for well-being. Although the expression or means of satisfying these needs may vary across cultures, their satisfaction is viewed as essential for
well-being in all cultures.”
June 2010 - From Oxford U Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 nm Size Particles.
"A shortage of disposable filtering facepiece respirators can be expected during a pandemic...
... To address the filtration performance of common fabric materials against nano-size particles including viruses, five major categories of fabric materials including sweatshirts, T-shirts, towels, scarves, and cloth masks were tested for polydisperse and monodisperse aerosols (20–1000 nm) at two different face velocities (5.5 and 16.5 cm s−1) and compared with the penetration levels for N95 respirator filter media. The results showed that cloth masks and other fabric materials tested in the study had 40–90% instantaneous penetration levels against polydisperse NaCl aerosols employed in the National Institute for Occupational Safety and Health particulate respirator test protocol at 5.5 cm s (1)."
Oct. 2008 - Predominant Role of Bacterial Pneumonia as a Cause of Death in Pandemic Influenza: Implications for Pandemic Influenza Preparedness
Fauci conducted a study in which the major finding was that the majority of deaths from the Spanish Flu Pandemic of 1918/1919 was not from the influenza virus, but from bacterial infection, which we are today seeing an alarming rise in due to the social use of face coverings. The recommendation to wear face coverings is therefore a deliberate act of harm which you can no longer plead ignorance to.
July 2020 - Community and Close Contact Exposures Associated with COVID-19 Among Symptomatic Adults ≥18 Years in 11 Outpatient Health Care Facilities
As a follow up to Fauci's 2008 findings, the CDC recently published data on hospital admissions which shows that those testing both positive and negative for the virus strain are presenting symptoms of covid-19, and that the vast majority of hospital admissions with severe respiratory symptoms are wearing face coverings.
April 2006 - Masks may cause hypoxia
"..  Third, the reproducibility of fi t testing over time has been questioned. 58 Fourth, prolonged use of N95 respirators has been shown to cause headaches, 59 facial discomfort, 60 and may result in hypoxia. 61 Therefore, we seriously question whether poor compliance would negate any potential benefi t that might be gained from their use. ..."
May 26, 2005 - “Effects of wearing N95 and surgical facemasks on heart rate, thermal stress and subjective sensations”
“Discussion: This first randomized cross-over study assessing the effects of surgical masks and FFP2/N95 masks on cardiopulmonary exercise capacity yields clear results. Both masks have a marked negative impact on exercise parameters such as maximum power output (Pmax) and the maximum oxygen uptake (VO2max/kg). FFP2/N95 masks show consistently more pronounced negative effects compared to surgical masks. Both masks significantly reduce pulmonary parameters at rest (FVC, FEV1, PEF) and at maximum load (VE, BF, TV). …
Pulmonary function: … The data of this study are obtained in healthy young volunteers, the impairment is likely to be significantly greater, e.g., in patients with obstructive pulmonary diseases (ref). From our data, we conclude that wearing a medical face mask has a significant impact on pulmonary parameters both at rest and during maximal exercise in healthy adults. 13
Cardiac function: … These data suggest a myocardial [relating to the muscular tissue of the heart] compensation for the pulmonary limitation in the healthy volunteers. In patients with impaired myocardial function, this compensation may not be possible.”
From 2004- The physiological impact of wearing an N95 mask during hemodialysis as a precaution against SARS in patients with end-stage renal disease.
"Most patients with end-stage renal disease (ERSD) visiting our hospital for hemodialysis treatment during the SARS outbreak wore an N95 mask. Data on the physiological stress imposed by the wearing of N95 masks remains limited. This study investigated the physiological impact of wearing an N95 mask during hemodialysis (HD) on patients with ESRD.
Each patient wore a new N95 mask (3M Model 8210) during HD (4 hours). Vital signs, clinical symptoms and arterial blood gas measured before and at the end of HD were compared.
Results - Thirty nine patients (23 men; mean age, 57.2 years or 70%) were recruited for participation in the study. Seventy percent of the patients showed a reduction in partial pressure of oxygen (PaO2), and 19% developed various degrees of hypoxemia. Wearing an N95 mask significantly reduced the PaO2 level.... increased the respiratory rate.... increased the occurrence of chest discomfort.... and respiratory distress
CONCLUSION- Wearing an N95 mask for 4 hours during HD significantly reduced PaO2 and increased respiratory adverse effects in ESRD patients"
Nov 2001 - Patient surgical masks during regional anesthesia. Hygenic necessity or dispensable ritual?
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.” https://pubmed.ncbi.nlm.nih.gov/11760479/
Nov2001 - Patient surgical masks during regional anesthesia. Hygenic necessity or dispensable ritual?
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.
February 5, 2021, (preprint) - “Impact of personal protective equipment use on health care workers’ physical health during the COVID-19 pandemic: a systematic review and meta-analysis”.
A systematic review and meta-analysis to “assess the impact of PPE use on HCWs’ physical health during the COVID19 pandemic”. Their “review included 14 studies with 11746 HCWs from 16 counties”:
“Results (Abstract): A total of 343 healthcare professionals on the COVID-19 front lines participated in this study [New York City]. 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.nn
Impaired cognition was reported in 81 respondents. … Some respondents experienced resolved side effects once masks were removed, while others required physical or medical intervention.
Conclusion (Abstract): 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. …”
Jan 27th, 2021- “Facemask headache: a new nosographic entity among healthcare providers in COVID-19 era”. Neurological Sciences
“Conclusion (Abstract): (A total of 155 healthcare workers responded to the questionnaire [Morocco].) The increased use of PPE, especially high filtrating masks during the COVID-19 outbreak is responsible for generating headaches in healthcare workers on frontline (62%) either De novo (33%) or as an aggravation of pre-existing one (29%). Working conditions have the greater impact on generating these types of headaches more than any pre-existing comorbidity.”
December 30, 2020 - Mask-associated ‘de novo’ headache in healthcare workers during the COVID-19 pandemic
“Results: … Out of 241 [Pakistan], 68 participants (28.2%) reported de novo headaches since the start of the pandemic, with majority describing the headache as bilateral in location ( n= 47, 69%), with pressure/heaviness in quality ( n = 31, 45.5%) and moderate in intensity ( n =45, 66%). … Out of the 68 participants with new-onset headaches, 16 (23.5%) stated that the headache started more than 2 hours after donning PPE, while 19 (27.9%) participants stated that the headache ended between 1-2 hours after doffing of PPE. Fifty-three respondents
(77.9%) experienced the headaches for 4 or less days per month. …”
December 14, 2020 - “Association of Personal Protective Equipment with De Novo Headaches In Frontline Healthcare Workers during COVID-19 Pandemic: A Cross-Sectional Study”. (DENTAL)
“…Several dermatoses [skin defects or lesions on the skin] have been reported due to PPE, such as pressure injury, contact dermatitis, pressure urticaria [hives] and exacerbation of pre‐existing skin diseases, including seborrheic dermatitis [scales] and acne.(2 refs) We report a preliminary data of HCW who experienced facial dermatoses due to the use of PPE. From 24 March 2020 to 16 April 2020, we came across with 43 patients comprising physicians, nurses
and paramedical staff who involved (directly/indirectly) in managing patients of COVID‐19 [India]. … The most commonly noted dermatoses were irritant contact dermatitis (ICD; 39.5%) followed by friction dermatitis (25.5%). Goggles were the most common culprit agent among all PPE causing any one of the dermatoses (51.92%), followed by N95 masks (30.77%) and face shields (17.31%). Nasal bridge (63%) was the commonest anatomical site affected due to dermatoses followed by cheeks and chin (26%). However, there was a considerable overlap of different dermatoses with affliction of multiple sites. The most common symptom experienced by patients was pruritus [itchiness] (67.44%), while erythema [redness] (53.49%) was the most common sign observed. Interestingly, we observed two distinct dermatoses, i.e. whole face erythema (suffusion; 21%) attributed to doffing after a long shift and lip lick dermatitis due to constant licking of lips, because of feeling of intense thirst due to restricted fluid intake after donning PPE. The duration of wearing the goggles and mask, excessive sweating and ill‐fitting masks, all were associated with increased sensation of irritation. Most of these dermatoses responded well to topical moisturizer, calamine lotion and oral antihistamines. Overall, 21% patients suffered from work absenteeism due to one of the dermatoses. Personal protective equipment‐induced dermatoses occur mainly due to the occlusion and hyper‐hydration effect of PPE and friction leading breach in the epidermal integrity.(ref) Recently, in China, authors
noted a very high prevalence, i.e. 97% of skin damages in first‐line HCW fighting COVID‐19.(ref)”
December 12, 2020 - “Personal Protective Equipment and Headaches: Cross-Sectional Study Among Moroccan Healthcare Workers During COVID- 19 Pandemic”. Cureus.
Results (Abstract): (315 participants, Turkey) … New-onset symptom rate was 66% (n=208).
The most common new-onset symptom was headache (n=115, 36.5%) followed by breathing difficulty-palpitation (n=79, 25.1%) and dermatitis (n=64, 20.3%). Extended use of PPE, smoking, and overweight were independently associated with developing new-onset symptoms. A clear majority of symptomatic participants pointed out impact on working performance (193/208, 92.7%).
November 19, 2020 - “Symptoms associated with personal protective equipment among frontline healthcare
professionals during the COVID-19 pandemic”. Disaster Medicine and Public Health Preparedness
“Results (Abstract): The subjects are n=306, 244 women (79.7%), with an average age of 43 years (range 23–65) [Spain]. Of the total, 129 (42.2%) were physicians, 112 (36.6%) nurses and 65 (21.2%) other health workers. 208 (79.7%) used surgical masks and 53 (20.3%) used filter masks. Of all those surveyed, 158 (51.6%) presented ‘de novo’ headache. The occurrence of a headache was independently associated with the use of a filter mask, OR 2.14 (95% CI 1.07 to 4.32); being a nurse, OR 2.09 (95% CI 1.18 to 3.72) or another health worker, OR 6.94 (95% CI 3.01 to 16.04); or having a history of asthma, OR 0.29 (95% CI 0.09 to 0.89). According to the type of mask used, there were differences in headache intensity, and the impact of a headache in the subjects who used a filter mask was worse in all the aspects evaluated.
Conclusion (Abstract): The appearance of ‘de novo’ headache is associated with the use of filter masks and is more frequent in certain healthcare workers, causing a greater occupational, family, personal and social impact.”
September 2020 - “Effects of Prolonged Use of Facemask on Healthcare Workers in Tertiary Care Hospital During COVID-19 Pandemic”. Indian J Otolaryngol Head Neck Surg 73, 59–65 (2021).
“Results (Abstract): A total of 158 healthcare workers participated in the study [Singapore].
Out of 158 respondents, 128 (81.0%) respondents developed de novo PPE-associated headaches. A pre-existing primary headache diagnosis (OR = 4.20, 95% CI 1.48-15.40; P = .030) and combined PPE usage for >4 hours per day (OR 3.91, 95% CI 1.35-11.31; P = .012) were independently associated with de novo PPE-associated headaches. Since COVID-19 outbreak, 42/46 (91.3%) of respondents with pre-existing headache diagnosis either "agreed" or "strongly agreed" that the increased PPE usage had affected the control of their background headaches, which affected their level of work performance.
Conclusion (Abstract): Most healthcare workers develop de novo PPE-associated headaches or exacerbation of their pre-existing headache disorders.
August 13, 2020 - “Personal protective equipment against COVID-19: Vital for surgeons, harmful for patients?”, The American Journal of Surgery.
On 13 August 2020, the surgeons Frountzas et al. warned that COVID-19 enthusiasm for imposing personal protective equipment (PPE) on surgeons could put surgery patients at risk (the equivalent can be said of train, tram, and bus drivers, and a large sector of workers servicing the public):
“Either in the case of a second lockdown or not, the safety of PPE use against COVID-19 for surgeons should be investigated. All parts of PPE increase surgeon's body temperature and sweating, leading to an impairment of surgeon's comfort, especially during prolonged and complicated surgical procedures. As mentioned above, PPE seems to be associated with important side effects, like dermatoses and headaches for healthcare workers. The PPE-associated discomfort and side effects during surgery may increase surgeons' anxiety and fatigue
while performing difficult operations.”
July 30, 2020 - Headaches, Personal Protective Equipment, and Psychosocial Factors Associated With COVID‐19 Pandemic (Comments, Observations, and Rebuttals)
"The study carried out by Ong et al.1 is noteworthy for the high level of clinical detail and the originality of the observation. The topographical relationship between the points of skin contact of the N95 face mask as well as protective eyewear with headache is novel and suggestive, and could give indications for the technical improvement of the devices. However, this research has some weaknesses, which only subsequent investigations can clarify.
In workplaces, where no pollution problems are reported, a significant share of indoor workers (6% of males, 9% of females) suffer “often, at least once a week” from headaches attributed to the working environment.2 This symptom is significantly associated with occupational stress.3 The individual characteristics of workers, in particular anxiety and depression, significantly influence the reporting of headache.4 Among health care workers, headache is associated with occupational stress5 and with sleep problems,6 as well as with anxiety and depression that were significantly increased during the COVID‐19 pandemics.7
This study did not take into account these variables. This may be a major limitation because the study population was drawn from high‐risk hospital areas such as isolation wards (designated as “pandemic wards”), the emergency rooms and medical intensive care unit. In these settings, workers are highly likely to experience emotional overload. The association between Personal Protective Equipment (PPE) and headache could be, therefore, spurious and the real factor should be sought among the psychosocial factors associated with the pandemic.
Furthermore, the study is entirely based on what workers remember of the situation before the epidemic, and this inevitably exposes to a possible recall bias.
We are convinced that the association between PPE and headache is worthy of controlled longitudinal studies, which compare different types of PPE and take into account all confounding factors."
June 1, 2020 - “Adverse Effects of Prolonged Mask Use among Healthcare Professionals during COVID-19”. Journal of Infectious Disease and Epidemiology
“Abstract: … All participants wore either surgical masks or N95 respirators for a minimum of 4 h per day [India]. … A total of 250 healthcare workers participated in the study … The acquired results were excessive sweating around the mouth accounting to 67.6%, difficulty in breathing on exertion 58.2%, acne 56.0% and itchy nose 52.0%. This study suggests that prolonged use of facemasks induces difficulty in breathing on exertion and excessive sweating around the mouth to the healthcare workers which results in poorer adherence and increased risk of susceptibility to infection.”
May 21, 2020 - Universal Masking in Hospitals in the Covid-19 Era
List of authors. Michael Klompas, M.D., M.P.H., Charles A. Morris, M.D., M.P.H., Julia Sinclair, M.B.A., Madelyn Pearson, D.N.P., R.N., and Erica S. Shenoy, M.D., Ph.D.
May 12, 2020 - Personal protective equipment induced facial dermatoses in healthcare workers managing Coronavirus disease 2019 (Letter to the Editor)
July 2020--Magnavita (critique of Ong, 2020): Magnavita, N. and Chirico, F. (2020),
“Headaches, Personal Protective Equipment, and Psychosocial Factors Associated With COVID
May 2020 - “Headaches Associated With Personal Protective Equipment - A Cross-Sectional Study Among Frontline Healthcare Workers During COVID-19”. Headache: The Journal of Head and Face Pain.
Apr 2020--“Headaches Associated With Personal Protective Equipment - A Cross-Sectional Study Among Frontline Healthcare Workers During COVID-19”. Headache: The Journal of Head and Face Pain.
Mar 2020 Adverse Effects of Prolonged Mask Use among Healthcare Professionals during COVID-19 (Survey)
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."
June 2015- As for surgeons wearing masks? Well, of course but the primary reason is to prevent blood splatter and not infection -
June 17, 2015 - “Unmasking the surgeons: the evidence base behind the use of facemasks in surgery”
"overall there is a lack of substantial evidence to support claims that face masks protect either patient or surgeon from infectious contamination"
Sept 2013 - Surgical attire and the operating room: role in infection prevention
An 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.”
Mar 2010 - Use of face masks by non-scrubbed operating room staff: a randomized controlled trial
Conclusion: Surgical site infection rates did not increase when non-scrubbed operating room personnel did not wear a face mask. https://pubmed.ncbi.nlm.nih.gov/20575920/
June 2009 - Use of surgical face masks to reduce the incidence of the common cold among health care workers in Japan: a randomized controlled trial
“Results: Thirty-two health care workers completed the study, resulting in 2464 subject days. There were 2 colds during this time period, 1 in each group. Of the 8 symptoms recorded daily, subjects in the mask group were significantly more likely to experience headache during the study period (P < .05). Subjects living with children were more likely to have high cold severity scores over the course of the study.
Conclusion: Face mask use in health care workers has not been demonstrated to provide benefit in terms of cold symptoms or getting colds. A larger study is needed to definitively establish non-inferiority of no mask use.
Apr-June 2009 - Does evidence based medicine support the effectiveness of surgical facemasks in preventing postoperative wound infections in elective surgery?
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.”
May 2008 - Surgical mask filter and fit performance (DENTAL)
Methods: Filter penetration was measured for at least 3 replicates of 9 surgical masks using mono disperse latex sphere aerosols (0.895, 2.0, and 3.1 micron) at 6 L/min and 0.075-micron sodium chloride particles at 84 L/min. Facial fit was measured on 20 subjects for the 5 masks with lowest particle penetration, using both qualitative and quantitative fit tests.
Results: Masks typically used in dental settings collected particles with significantly lower efficiency than those typically used in hospital settings. All subjects failed the unassisted qualitative fit test on the first exercise (normal breathing). Eighteen subjects failed the assisted qualitative fit tests; 60% failed on the first exercise. Quantitative fit factors ranged from 2.5 to 9.6.
Conclusion: None of these surgical masks exhibited adequate filter performance and facial fit characteristics to be considered respiratory protection devices.
July 1, 1991 - Surgical face masks in modern operating rooms—a costly and unnecessary ritual
“Oral microbial flora dispersed by unmasked male and female volunteers standing one metre from the table failed to contaminate exposed settle plates placed on the table. The wearing of face masks by non-scrubbed staff working in an operating room with forced ventilation seems to be unnecessary."
May 1991 - Postoperative wound infections and surgical face masks: A controlled study
“It has never been shown that wearing surgical face masks decreases postoperative wound infections. 'On the contrary, a 50% decrease has been reported after omitting face masks......
After 1,537 operations performed with face masks, 73 (4.7%) wound infections were recorded and, after 1,551 operations performed without face masks, 55 (3.5%) infections occurred. This difference was not statistically significant (p> 0.05) and the bacterial species cultured from the wound infections did not differ in any way, which would have supported the fact that the numerical difference was a statistically “missed” difference.
These results indicate that the use of face masks might be reconsidered. "
1981 - “Is a mask necessary in the operating theatre?” (pg 391 first paragraph under Table 1)
"There was no increase in wound infections be interesting to see whether comparable results when masks were discarded in I980; in fact are obtained in emergency, orthopaedic, or designed only to see whether wound infection in- there was a significant (p<o.o5) decrease." Note, their references date back as far as 1905.