“Abstract: Nose and mouth covering (NMC) has been made compulsory for children in many countries during the Covid-19 pandemic. We wanted to determine the average CO2 levels in inhaled air with NMC in children between age 6 and 17... We measured 13,100 ppm (SD 380) under surgical mask and 13,900 ppm (SD 370) under FFP2 mask in inhaled air... Wearing of NMC (surgical masks or FFP2- -masks) raises CO2 content in inhaled air quickly to a very high level in healthy children in a seated resting position that might be hazardous to children's health…
Introduction: … Maximum concentration at the work place for healthy adults during 8 h of work and 40 h per week as a time-weighted average is considered 0.5 vol% or 5,000 ppm. This limit is accepted in many countries, for instance in Germany (Institut für Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung, 2021) or in the United States (Centers for Disease Control and Prevention (CDC), 2019).”