Nitrous oxide, commonly known as laughing gas, is a sedative gas normally used for long duration procedures or for patients with low pain threshold. You must be clinically fit to be able to be administered the gas. Nitrous oxide is normally administered through a nose cap(nasal hood) which in turn is connected to two cannisters of gas : Oxygen and Nitrous Oxide. An average person will feel the effect at 30-40% Nitrous oxide, effect includes numbness of fingers and toes and slight euphoria.