Most of the complaints reported by children3 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.Experimental Assessment of Carbon Dioxide Content in Inhaled Air With or Without Face Masks in Healthy Children