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Possible toxicity of chronic carbon dioxide exposure associated with mask use, particularly in pregnant women, children and adolescents -a scoping review

Literature was systematically reviewed regarding CO
exposure and facemask use. Observational and experimental data are
helpful for a risk-benefit assessment for masks as a popular
non-pharmaceutical intervention against SARS-CoV2 in the populace. Masks
impede breathing by increasing the resistance and dead space volume
leading to a re-breathing of CO with every breath
taken. Fresh air has around 0.04% CO, while wearing
masks more than 5 minutes bears a possible chronic exposure to carbon
dioxide of 1.41% to 3.2% of the inhaled air. Although the buildup is
usually within the short-term exposure limits, long-term consequences
must be considered due to experimental data. US Navy toxicity experts
set the exposure limits for submarines carrying female crews to 0.8%
CO based on animal studies indicating an increased risk
for stillbirths. Additionally, in mammals chronically exposed to 0.3%
CO experimental data demonstrates teratogenicity with
irreversible damage of neurons and reduced spatial learning caused by
brainstem neuron apoptosis and a reduced blood level of the insulin-like
growth factor 1. With significant impact on three readout parameters
(morphological, functional, marker) this chronic 0.3%
CO exposure has to be defined as being toxic.
Additional data exists on the exposure of chronic 0.3%
CO in adolescent mammals causing neuron destruction,
which includes less activity, increased anxiety and impaired learning
and memory. There is a possible negative impact risk by imposing
extended mask mandates especially for vulnerable subgroups.
Circumstantial evidence exists that extended mask use may be related to
current observations of stillbirths and to reduced verbal motor and
overall cognitive performance in children born during the pandemic.
Extended masking in pregnant women, children and adolescents has not
been thoroughly tested and studied. As a result of the animal
experimental data available, a risk-benefit analysis is urgent and a
need exists to rethink mask mandates, which provide appropriate
warnings.