In addition to hypoxia and hypercapnia, breathing through facemask residues bacterial and
germs components on the inner and outside layer of the facemask. These toxic components are
repeatedly rebreathed back into the body, causing self-contamination. Breathing through
facemasks also increases temperature and humidity in the space between the mouth and the
mask, resulting a release of toxic particles from the mask’s materials [1], [2], [19], [26], [35], [36].
A systematic literature review estimated that aerosol contamination levels of facemasks
including 13 to 202,549 different viruses [1]. Rebreathing contaminated air with high bacterial
and toxic particle concentrations along with low O2 and high CO2 levels continuously challenge
the body homeostasis, causing self-toxicity and immunosuppression [1], [2], [19], [26], [35], [36].
A study on 39 patients with renal disease found that wearing N95 facemask during hemodialysis
significantly reduced arterial partial oxygen pressure (from PaO2 101.7 to 92.7 mm Hg),
increased respiratory rate (from 16.8 to 18.8 breaths/min), and increased the occurrence of
chest discomfort and respiratory distress [35]. Respiratory Protection Standards from
Occupational Safety and Health Administration, US Department of Labor states that breathing
air with O2 concentration below 19.5% is considered oxygen-deficiency, causing physiological
and health adverse effects. These include increased breathing frequency, accelerated heartrate
and cognitive impairments related to thinking and coordination [36]. A chronic state of mild
hypoxia and hypercapnia has been shown as primarily mechanism for developing cognitive
dysfunction based on animal studies and studies in patients with chronic obstructive pulmonary
disease [44].
The adverse physiological effects were confirmed in a study of 53 surgeons where surgical
facemask were used during a major operation. After 60 min of facemask wearing the oxygen
saturation dropped by more than 1% and heart rate increased by approximately five beats/min
[45]. Another study among 158 health-care workers using protective personal equipment
primarily N95 facemasks reported that 81% (128 workers) developed new headaches during
their work shifts as these become mandatory due to COVID-19 outbreak. For those who used
the N95 facemask greater than 4 h per day, the likelihood for developing a headache during the
work shift was approximately four times higher [Odds ratio = 3.91, 95% CI (1.35–11.31) p =
0.012], while 82.2% of the N95 wearers developed the headache already within ≤10 to 50 min
[46].
With respect to cloth facemask, a RCT using four weeks follow up compared the effect of cloth
facemask to medical masks and to no masks on the incidence of clinical respiratory illness,
influenza-like illness and laboratory-confirmed respiratory virus infections among 1607
participants from 14 hospitals [19]. The results showed that there were no difference between
wearing cloth masks, medical masks and no masks for incidence of clinical respiratory illness
and laboratory-confirmed respiratory virus infections. However, a large harmful effect with more
than 13 times higher risk [Relative Risk = 13.25 95% CI (1.74 to 100.97) was observed for
influenza-like illness among those who were wearing cloth masks [19]. The study concluded
that cloth masks have significant health and safety issues including moisture retention, reuse,
poor filtration and increased risk for infection, providing recommendation against the use of
cloth masks [19].

Psychological effects of wearing facemasks
Psychologically, wearing facemask fundamentally has negative effects on the wearer and the
nearby person. Basic human-to-human connectivity through face expression is compromised
and self-identity is somewhat eliminated [47], [48], [49]. These dehumanizing movements
partially delete the uniqueness and individuality of person who wearing the facemask as well as
the connected person [49]. Social connections and relationships are basic human needs, which
innately inherited in all people, whereas reduced human-to-human connections are associated
with poor mental and physical health [50], [51]. Despite escalation in technology and
globalization that would presumably foster social connections, scientific findings show that
people are becoming increasingly more socially isolated, and the prevalence of loneliness is
increasing in last few decades [50], [52]. Poor social connections are closely related to isolation
and loneliness, considered significant health related risk factors [50], [51], [52], [53].

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