How about starting with a sincere and profound apology to the children?
“The peer-reviewed research letter from Dr. Harald Walach and colleagues found that the air masked children inhaled contained more than six times the legal safe limit for closed rooms as set down by the German Federal Environmental Office. The safe limit is 0.2%, whereas the air the masked children inhaled contained over 1.3% carbon dioxide.
The effect was worse for younger children, with one seven year-old child inhaling air with 2.5% carbon dioxide, over 12 times the safe limit.”