Why is fresh air especially important for preschool children?

Preschool children have strong metabolism, shallow breathing, fast frequency, poor lung ventilation and need a lot of fresh air. Pay attention to indoor ventilation and try to let children exercise outdoors. The blood of preschool children contains more water and serum, but less salt. Preschool children's brains need more oxygen, and children's brain tissues are very sensitive to hypoxia and have poor tolerance to hypoxia. Therefore, keeping the air fresh in children's living environment is very important for the normal development of their nervous system and the maintenance of good functional status.