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The Physiological Effects of Masks


Do masks inhibit the free flow of oxygen and carbon dioxide? Can this account for the symptoms being reported such as headache, fatigue, poor attention span, poor cognition, etc?
When a CO2 monitor is placed in a normal medical mask, within seconds, the concentration of CO2 reaches unacceptable levels inside of the mask. N95 respirators are even worse.  This is the "ambiant air quality" you are breathing. 

OSHA experts weigh in on mask mandates. *see replies to "fact checkers" below."


Watch video here.

The CDC denies that masks cause "CO2 poisoning" (levels that reach 30-40,000 ppm),  however the CDC does NOT address the levels inside of masks over 1000 ppm which have been determined to be  unhealthful and unacceptable air quality in a room, school, building or work environment by OSHA and other agencies (see research below).
Breathing oxygen is beyond a fundamental human right, it's a biological necessity. 

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Experimental Assessment of Carbon Dioxide Content in Inhaled Air With or Without Face Masks in Healthy Children: A Randomized Clinical Trial
Journal of the American Medical Association (JAMA)

June 30, 2021


The mean (SD) age of the children was 10.7 (2.6) years (range, 6-17 years), and there were 20 girls and 25 boys.  We measured means (SDs) between 13 ,120 (384) and 13 ,910 (374) ppm of carbon dioxide in inhaled air under surgical and filtering facepiece (FFP2) masks, which is higher than what is already deemed unacceptable by the German Federal Environmental Office by a factor of 6. This was a value reached after 3 minutes of measurement. Children under normal conditions in schools wear such masks for a mean of 270 (interquartile range, 120-390) minutes.3 The Figure shows that the value of the child with the lowest carbon dioxide level was 3-fold greater than the limit of 0.2 % by volume.  The youngest children had the highest values, with one 7-year-old child’s carbon dioxide level measured at 25 000 ppm.


The limitations of the study were its short-term nature in a laboratory-like setting and the fact that children were not occupied during measurements and might have been apprehensive. Most of the complaints reported by children can be understood as consequences of elevated carbon dioxide levels in inhaled air. This is because of the dead-space volume of the masks, which collects exhaled carbon dioxide quickly after a short time. This carbon dioxide mixes with fresh air and elevates the carbon dioxide content of inhaled air under the mask, and this was more pronounced in this study for younger children.

This leads in turn to impairments attributable to hypercapnia. A recent review6 concluded that there was ample evidence for adverse effects of wearing such masks. We suggest that decision-makers weigh the hard evidence produced by these experimental measurements accordingly, which suggest that children should not be forced to wear face masks.

Unfortunately, this groundbreaking study has been "retracted" (essentially, censored). Please see the author's response here.



Indoor carbon dioxide levels could be a health hazard, scientists warn.

The Guardian
July 8 2019

Note: CO2 levels inside masks can reach over 10,000 ppm in a matter of minutes or even seconds. This study shows negative effects start at 1000 ppm.

Indoor levels of carbon dioxide could be clouding our thinking and may even pose a wider danger to human health, researchers say.

While air pollutants such as tiny particles and nitrogen oxides have been the subject of much research, there have been far fewer studies looking into the health impact of CO2.


However, the authors of the latest study – which reviews current evidence on the issue – say there is a growing body of research suggesting levels of CO2 that can be found in bedrooms, classrooms and offices might have harmful effects on the body, including affecting cognitive performance.

“There is enough evidence to be concerned, not enough to be alarmed. But there is no time to waste,” said Dr Michael Hernke, a co-author of the study from the University of Wisconsin-Madison, stressing further research was needed.

Writing in the journal Nature Sustainability, Hernke and colleagues report that they considered 18 studies of the levels of CO2 humans are exposed to, as well as its health impacts on both humans and animals.

Traditionally, the team say, it had been thought that CO2 levels would need to reach a very high concentration of at least 5,000 parts per million (ppm) before they would affect human health. But a growing body of research suggests CO2 levels as low as 1,000ppm could cause health problems, even if exposure only lasts for a few hours.

The team say crowded or poorly ventilated classrooms, office environments and bedrooms have all been found to have levels of CO2 that exceed 1,000ppm, and are spaces that people often remain in for many hours at a time. Air-conditioned trains and planes have also been found to exceed 1,000ppm.

“Indoor environments are of much more concern presently and for many people that is where they spend 60-80% of their time,” said Hernke, although projections suggest by 2100 some large cities might reach outdoor CO2 levels of 1,000ppm for parts of the year.

The team found a number of studies have looked at the impact of such levels on human cognitive performance and productivity.


Ione study from Harvard of 24 employees, cognitive scores were 50% lower when the participants were exposed to 1,400ppm of CO2 compared with 550ppm during a working day.

The team additionally looked at the impact of CO2 levels on animals, finding that a few hours’ exposure to 2,000 ppm was linked to inflammatory responses that could lead to damage to blood vessels. There is also tentative evidence suggesting that prolonged exposure to levels between 2,000 and 3,000ppm is linked to effects including stress, kidney calcification and bone demineralisation.

The team add that rising outdoor levels of CO2 will mean rising indoor levels – a situation that could be exacerbated by greater use of certain air-conditioning units, people spending more time inside, energy-saving building techniques, and increasing urbanisation.

Any health impacts, they add, might be particularly problematic for children or those with health conditions that might exacerbate the effects. And even if the impacts are reversible, said Hernke, it would depend on people being able to access air with low levels of CO2. “The question is what happens over the very long term when you are unable to go outside and, as it were, have that carbon sucked back out of you?”

Dr Gary Fuller, an air pollution scientist at King’s College London, said his team had been measuring CO2 levels in London for the past decade. While levels rarely reached 1,000ppm, he said, they often exceeded 750ppm along busy roads. “Unless we decarbonise heating and transport then these peaks will worsen as the global background increases,” he said.

Effects of low-level inhalation exposure to carbon dioxide in indoor environments: A short review on human health and psychomotor performance.
December 2018


Direct effects of low-level CO2 exposure on human health should be focused.

Physiological changes occur at CO2 exposures levels between 500 and 5000 ppm.

Effects on cognitive performance begin at 1000 ppm during short-term exposure.

A total of 1475 articles were retrieved. After exclusion of duplicate publications, the retrieved articles were reviewed by a reviewer (KA) in two stages: screening of titles and abstracts, followed by full-text review. Additional articles were identified based on prior knowledge (e.g., documents or reports of international or national organizations) and by manual screening of the bibliographies of the retrieved articles. A total of 99 full-text articles were reviewed. Only peer-reviewed articles pertaining to original research or review of experimental or human studies directly associated with health and related response to exposure to CO2, which clearly identified the air concentration of CO2, were considered. 

Recent studies show clear linear physiological changes in circulatory, cardiovascular, and autonomic systems, including an increase of pCO2 in the blood, elevated blood pressure, increased heart rate, increased peripheral blood circulation, and increased sympathetic stimulation at CO2 exposures in the range of 500 to 5000 ppm.


Normalizing CO2 in chronic hyperventilation by means of a novel breathing mask: a pilot study

October 7, 2013

Introduction: Chronic idiopathic hyperventilation (CIH) is a form of dysfunctional breathing that has proven hard to treat effectively.

Objectives: To perform a preliminary test of the hypothesis that by periodically inducing normocapnia over several weeks, it would be possible to raise the normal resting level of CO2 and achieve a reduction of symptoms.

Methods: Six CIH patients were treated 2 h a day for 4 weeks with a novel breathing mask. The mask was used to induce normocapnia in these chronically hypocapnic patients. Capillary blood gases and acid/base parameters [capillary CO2 tension (PcapCO2 ), pH, and standard base excess (SBE)] were measured at baseline and once each week at least 3 h after mask use, as well as spirometric values, breath-holding tolerance and hyperventilation symptoms as per the Nijmegen Questionnaire (NQ).

Results: The mask treatment resulted in a significant increase of resting PcapCO2 (+0.45 kPa, P = 0.028), a moderate increase in SBE (+1.4 mEq/L, P = 0.035) and a small reduction in daily symptoms (-3.8 NQ units, P = 0.046). The effect was most pronounced in the first 2 weeks of treatment.

Conclusion: By inducing normocapnia with the breathing mask

2 h a day for 4 weeks, the normal resting CO2 and acid/base levels in chronically hyperventilating patients were partially corrected, and symptoms were reduced.

Keywords: breathing mask; dysfunctional breathing; hyperventilation; hypocapnia; rebreathing; respiratory acidosis; respiratory alkalosis.

COVID-19: Electrophysiological mechanisms underlying sudden cardiac death during exercise with facemasks
August 11, 2020

The mandatory use of facemasks is a public health measure implemented by various countries in response to the novel coronavirus disease 19 (COVID-19) pandemic. However, there have been case reports of sudden cardiac death (SCD) with the wearing of facemasks during exercise. In this paper, we hypothesize that exercise with facemasks may increase the risk of ventricular tachycardia/ventricular fibrillation (VT/VF) leading to SCD via the development of acute and/or intermittent hypoxia and hypercapnia. We discuss the potential underlying mechanisms including increases in adrenergic stimulation and oxidative stress leading to electrophysiological abnormalities that promote arrhythmias via non-reentrant and reentrant mechanisms. Given the interplay of multiple variables contributing to the increased arrhythmic risk, we advise avoidance of a facemask during high intensity exercise, or if wearing of a mask is mandatory, exercise intensity should remain low to avoid precipitation of lethal arrhythmias. However, we cannot exclude the possibility of an arrhythmic substrate even with low intensity exercise especially in those with established chronic cardiovascular disease in whom baseline electrophysiological abnormalities may be found.

"Exercise with facemask; Are we handling a devil's sword?"

November 2020


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.

Ewa Messaoudi, who handles the regulation of protective respiratory devices at AFNOR, the French organization that implements product standards:

"It’s important to take into account that this kind of protection is always a constraint for the human body. We don’t wear a mask for respiratory comfort, we wear it to protect ourselves against an existing risk. What’s important to establish is if the mask allows the human body to meet its physiological needs for the limited period when it is being used. When we develop masks, we model them on technical specifications based on human factors, like European norms of standardization (note: there is no definition of what a "limited period" actually is.)

So, yes, the level of CO2 does go up when you wear a mask but it remains an acceptable level for the human body. That’s the case for masks certified by the CWA 17553 

[Editor’s note: the Committee Workshop Agreement of the European Normalization Committee, which provides information about these masks on this document]."

Preliminary report on surgical mask induced deoxygenation during major surgery


Summary Objectives. This study was undertaken to evaluate whether the surgeons' oxygen saturation of hemoglobin was affected by the surgical mask or not during major operations.

Methods. Repeated measures, longitudinal and prospective observational study was performed on 53 surgeons using a pulse oximeter pre and postoperatively.

Results When the values for oxygen saturation of hemoglobin were compared, there were statistically significant differences only between preoperational and post operational values.  As the duration of the operation increases, oxygen saturation of hemoglobin decreases significantly. Neither preoperational values, nor the post operational values in themselves were different among the groups. In the group of surgeons who did not wear masks during primary care operations with duration of less than 30 minutes, preoperational saturation values were 97.6±0.2 while post operational values decreased to 96.3±0.3 (p=0.0006).

Carbon dioxide rebreathing in respiratory protective devices: influence of speech and work rate in full-face masks

Overall, the results of the study indicate speech and low work rates significantly increase CO2 rebreathing in RPDs. Based on Australian respirator design standards it is evident speech could contribute to inspired CO2 exceeding the maximal allowable concentrations in inspired air. However, the impact of gender and body size on CO2 levels could not be ascertained. The implication of these findings is that high CO2 concentrations in full face RPDs may be linked to wearer discomfort and contribute to reduced tolerability and wear time of the device. Since many occupations require workers to communicate while wearing RPDs these findings must be taken into consideration. It is recommended that the findings in this study be considered in the design and use of RPDs.

* Replies to "fact checkers" on CO2 levels in masks as measured by a CO2 meter.

Most of the "fact checkers" are addressing (and dismissing) the severe CO2 "poisoning" that can happen at higher levels of exposure and not the physical effects of longer term lower exposures of mask wearing.

Both OSHA PPE experts Kristen Meghan and Tammy Clark confirm that testing in the breathing zone is the way they were instructed in their OSHA training (see video above) and measuring behind a mask is a valid test.

Critics are also blaming the meter's inability to reset quickly for the high readings. However, when you leave the meter inside the mask and breathe normally for five or more minutes, the meter remains at extremely elevated levels


Flawed experiments exaggerate risk from CO2 concentration in masks

“There is no doubt that wearing a face mask will increase carbon dioxide levels,” Choi conceded. However, the researcher warned that Bigtree’s video misleads by presenting the 5,000 ppm mark as a definite marker of toxicity.  Five thousand ppm is the highest recommended exposure for people working eight-hour days every day, particularly in closed spaces.

The experiments further mislead by truncating the chart, making 5,000 ppm look like the highest mark, when in fact the real chart shows that 40,000 ppm and above is the level considered dangerous, even for short periods of time..

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