In many parts of the United States, there is no age minimum required to own or use an air rifle. In the United Kingdom, though, the minimum age to own an air rifle is 18, with restrictions on handling and use before that age.
The U.S. government does not regulate air rifles because they are not considered firearms under the Gun Control Act of 1968. According to the definition contained within that act, firearms use explosives to propel projectiles; air rifles use compressed air. California, Massachusetts, Pennsylvania and Michigan prohibit air rifle ownership to anyone under the age of 18. New York, Delaware and Maine prohibit ownership to anyone under 16.