“What age is safe for anesthesia?”

Anesthesia is safe almost at any age

There is no specific age that can be considered "unsafe" or "safe" for anesthesia. Anesthesia is administered to persons of all ages from newborn babies, who may be not even a few hours old all the way up to very elderly patients, even those who are over 100 years old. The relative risks of anesthesia administration have much more to do with the patients co-existing medical conditions which they bring to that point of anesthesia administration, instead of the patient's age.

Sorry. There is no age. Anesrhesia is a risk at any age.