Anesthesia is not dangerous for children if it's done correctly.

Have to review each case

Children are delicate and they have to monitored properly as their situation can change very rapidly

Anesthesia is not dangerous for children.  There is a hereditary condition known as malignant hyperthermia that can be triggered by certain anesthetics.  If a child's parent is unaware that their child has this condition, harm, including death, can occur.  However, a good medical history involving family members and their exposure to anesthesia should be obtained prior to any exposure to an anesthetic.

On a smaller scale everything is different but not necessarily so in expert hands who are used to taking care of the children.

I believe children under 3 years should not be exposed to general anesthesia toxicity due to immature SNC brain, unless it's completely necessary. And there are also some genetic diseases that only show up under general anesthesia and could be fatal. It's important for you to discuss this with the anesthesiologist and pediatrician before an elective surgery.