The oxygen bar is a tren that started in the late 1990s in Japan, and quickly spread east to California and Las Vegas. Used for health and recreation as well, O2 bars can now be found in many venues such as nightclubs, salons, spas, healthclubs, resorts, tanning salons, restaurants, coffee houses, bars, airports, ski chalets, yoga studios, chiropractors, and casinos. They can be found at trade shows, conventions and corporate meetings, as well as at private parties and promotional events. Oxygen Bar guests will normally pay $1.00 USD per minute to inhale an increased percentage of oxygen compared to the normal atmospheric content of 21% oxygen. This oxygen is produced from the ambient air by an industrial (non-medical) oxygen concentrator and inhaled through a nasal cannula or headset for a period of 5 to 10 minutes - or even longer. Medical grade oxygen through a nasal cannula typically delivers only a 33% concentration at a flow rate of 3lpm. While greater concentrations are possible via a nasal cannula at higher flow rates, these tend to be increasingly uncomfortable. Concentrations approaching 100% are only possible through a full face mask such as a non-rebreather mask at flow rates over 6lpm. The FDA has warned against the use of industrial generators. http://www.fda.gov/fdac/features/2002/602_air.html as they do not have the proper filtration and high concentrations can cause difficulties in breathing for some people with medical conditions. Several states including Texas, Iowa, Massachusetts have banned the use of industrial generators for recreational oxygen breathing. While industrial generators are deemed unsafe by some states, recreational oxygen levels of 30% are legal. 30% levels raise the blood oxygen levels slowly with no danger of overdose. The latest technology of oxygen bar equipment offers membrane technology developed specifically for recreational use and also Oxygen Vending units are set at a safe level to avoid liability and to pass legal rigor in the USA.