They are selling air at WalMart. No, I am not kidding. Look at these pictures.
Actually, they are selling cans of oxygen. According to the label, the gas in these cans is 95% oxygen with 5% other inert gases. The idea, it seems, is to breathe a hit of oxygen and it will relieve fatigue, give you strength and endurance, and make you feel better. I have no idea whether this would actually work. I do know that it is not really a good idea to breathe pure oxygen.
Oxygen is actually a toxin. I know that we need oxygen for our metabolism, but the property that makes oxygen so useful in digestion also makes it dangerous. Oxygen is a highly reactive element. Oxygen atoms eagerly take electrons from other atoms and readily form compound. When this happens quickly we call it fire. Oxidation that occurs more slowly, we call rusting or corrosion. Excessive levels of oxygen in the body can do a lot of damage.
Oxygen toxicity is a condition resulting from the harmful effects of breathing molecular oxygen (O2) at elevated partial pressures. It is also known as oxygen toxicity syndrome, oxygen intoxication, and oxygen poisoning. Historically, the central nervous system condition was called the Paul Bert effect, and the pulmonary condition the Lorrain Smith effect, after the researchers who pioneered its discovery and description in the late 19th century. Severe cases can result in cell damage and death, with effects most often seen in the central nervous system, lungs and eyes. Oxygen toxicity is a concern for scuba divers, those on high concentrations of supplemental oxygen (particularly premature babies), and those undergoing hyperbaric oxygen therapy.
The result of breathing elevated concentrations of oxygen is hyperoxia, an excess of oxygen in body tissues. The body is affected in different ways depending on the type of exposure. Central nervous system toxicity is caused by short exposure to high concentrations of oxygen at greater than atmospheric pressure. Pulmonary and ocular toxicity result from longer exposure to elevated oxygen levels at normal pressure. Symptoms may include disorientation, breathing problems, and vision changes such as myopia. Prolonged or very high oxygen concentrations can cause oxidative damage to cell membranes, the collapse of the alveoli in the lungs, retinal detachment, and seizures. Oxygen toxicity is managed by reducing the exposure to elevated oxygen levels. Studies show that, in the long term, a robust recovery from most types of oxygen toxicity is possible.
Protocols for avoidance of hyperoxia exist in fields where oxygen is breathed at higher-than-normal partial pressures, including underwater diving using compressed breathing gases, hyperbaric medicine, neonatal care and human spaceflight. These protocols have resulted in the increasing rarity of seizures due to oxygen toxicity, with pulmonary and ocular damage being mainly confined to the problems of managing premature infants.
I don’t suppose the oxygen in those cans would do any damage, unless someone kept holding one up to his face and breathed in hit after hit, but I don’t imagine anyone foolish enough to spend $10 for a can of air is doing themselves any good.