Nitrous oxide became known as “laughing gas” because of its transient mood-elevating effects and has since been used for several centuries as a harmless way of having a short-lived funny experience. For the past 150 years, nitrous oxide has been inhaled as a gas by hundreds of millions of people in medical settings for pain control. In this circumstance, it is breathed, usually in a fixed combination mixture with oxygen to produce pain control.....