Airsoft is a fast growing worldwide sport notably in the U.S.A, Japan,Philippines, china and the Uk. Many new Chinese airsoft guns are dominating the airsoft market because they are more affordable. Guns are usually the most expensive piece of equipment. airsoft guns are more frail and vulnerable to breakage than real-steel firearms due to the use of less dense and cheaper metals and plastics
Shot from a BB on bare skin from a gun with a velocity over 400 FPS will usually break the skin and cause minor bleeding. The game is basically like playing paintball but instead of paintballs you fire BB, Some of these guns can fire up-to 750 feet per second which is quite powerful and could easily go through 2 tin cans. The guns are easy to get hold of with many online stores before.
Airsoft games have lists of rules and marshals and are usually conducted professionally on site but their are a lot of people who play their own games. As for an age limit i just don't know what that should be but i believe their should be one. I mean some teens are more mature than others and would be responsible with an airsoft gun.
So i think for sure they are unsafe in the hands of children, but teens should be fine providing they where goggles, traditional prescription glasses and sunglasses are almost never accepted at airsoft sites. Always will be accidents when games of this nature are being played. Airsoft is not for children that i am sure but accompanied by an adult then younger children should be alright also. It is a fun game and should be played with respect and eye protection if people do that no one will get blinded. So really it should be a parents decision weather or not you let your child play Airsoft. This is a fun game but should be treated with respect.