The lung of the hot tub or hypersensitivity pneumonitis is a disease that has been associated with indoor hot tub use. This disease is quite rare and is also known as "lifeguard's lung" as it can also be connected with indoor swimming pools. It is often misdiagnosed as other lung diseases, such as tuberculosis.
Hypersensitivity pneumonitis is caused by inhalation of endotoxins, which are fragments of a bacterium (Mycobacterium avium) that have been aerosolized by steam and bubbling water. Outdoor spas are much less likely to cause hot tub lung, as there are no problems with ventilation. Even with indoor hot tubs and pools, this condition is rare and usually occurs in people who frequently use the hot tub or pool for a long period of time.
The endotoxins that cause hot tub lung are contained in a certain type of bacteria that can sometimes harbor in water circulation systems. These systems can have biofilm growing on them if they are not sanitized regularly. If the slimy biofilm is disrupted in some way, such as pressure from jets in a hot tub, the bacteria are released into the water and break down, releasing the endotoxins into the water.
Symptoms of hot tub lung include fever, fatigue, cough, lack of appetite, night sweats, shortness of breath, and weight loss. People suffering from hot tub lung should stop using the hot tub or indoor pool immediately. Corticosteroids may be prescribed, as well as supplemental oxygen for extreme cases. Medical professionals disagree about whether antibiotics cure hypersensitivity pneumonitis or whether it is better to let it get better without any antibiotic treatment.
To prevent hot tub lungs, hot tubs and indoor pools always have a sufficient level of disinfectant in the water. Ventilation in the area is also important, to ensure fresh air circulates and dilutes endotoxins in the air. The water in spas or pools should also be changed regularly and have the correct balance and filtration needed. If a spa hasn't been used for a while, they should be sanitized before being used again. While sanitizing, all jets must be turned on so that the entire water system comes into contact with the sanitizer.