This article was published under Open Access. CC BY-NC 4.0 DEED, Attribution-NonCommercial 4.0 International
“Introduction: Surgical masks and respirators are assumed to reduce the spread of SARS-CoV-2,2 and are believed to decrease the incidence of other airborne infections. On the other hand, a prolonged mask use has been associated with higher viral loads and more severe symptoms in infected people (possibly due to the re-inhalation of viral particles trapped in the mask), with skin disorders due to pathogens contamination, a higher likelihood of frequent cough, sputum production, dyspnea, and panic attacks, with delayed cognitive development in infants, and with a substantial rise of inhaled carbon dioxide (CO2), which in turn may cause other symptoms.
Few studies, however, directly assessed CO2 in air inhaled while wearing masks in the general population…
With the present study, we aimed at expanding the evidence about the potential inhalation of excess CO2 as a consequence of wearing surgical masks or FFP2 respirators, among adults, children, and the elderly. Therefore, we used a professional real-time capnograph, with water-removal tubing, in order to assess the inhaled air CO2 concentration in a sample of healthy individuals wearing different types of masks…
Data analysis: The primary outcome was the mean inhaled air CO2 concentration when wearing masks. The secondary outcome was the proportion of individuals with inhaled air CO2 concentration exceeding 5000?ppm, which is the long-term (8-hours average) threshold indicated as Permissible Exposure Limit by the United States Department of Labor Occupational Safety and Health Administration (OSHA), and as Indicative Occupational Exposure Limit by the European Agency for Safety and Health at Work (EU-OSHA)…
Outcomes: The mean inhaled air CO2 without masks was 460 ± 20 ppm. While wearing the surgical mask, the mean CO2 was 5087 ± 1579 ppm (95% confidence interval 4828-5346 ppm), and exceeded 5000 ppm in 41.1% (33.0%-49.5%) of the measurements. While wearing the FFP2 respirator, the average CO2 was 9653 ± 2874 ppm (9183-10 123 ppm), and 98.6% (95.2%-99.8%) of the participants showed values higher than 5000 ppm (Table 1). Among the minors, the mean CO2 concentration when wearing surgical masks was 7091 ± 2491 ppm (6039-8144 ppm), and was considerably higher than among the adults (4835 ± 869 ppm; P < .01), or the elderly (4379 ± 978 ppm; P < .001). A similar difference by age class was observed also for the FFP2 respirators (Table 2).
Note: According to this 2016 article published by Occupational Safety and Health (OSH), a CO2 level exceeding 5,000 ppm “indicates unusual air conditions where high levels of other gases also could be present. Toxicity or oxygen deprivation could occur“: