Hot tub lung, or hypersensitivity pneumonitis, is a disease that has become associated with indoor hot tub use. This disease is fairly rare, and is also known as "lifeguard lung," since it can be connected with indoor pools as well. It is often misdiagnosed as other lung diseases, such as tuberculosis.
Hypersensitivity pneumonitis is caused by inhaling endotoxins, which are fragments of a bacteria (Mycobacterium avium) which have become aerosolized by the steaming and bubbling water. Outdoor spas are much less likely to cause hot tub lung, since there are no issues with ventilation. Even with indoor hot tubs and indoor 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 which cause this condition are contained in a certain type of bacteria that can sometimes be harbored in water circulation systems. These systems can have biofilm growing in them if they are not sanitized regularly. If the slimy biofilm is disrupted in any way, such as the pressure from jets in a hot tub, the bacteria are then released into the water and break down, releasing the endotoxins into the water.
Symptoms of hot tub lung include fever, fatigue, coughing, lack of appetite, night sweats, trouble breathing, and weight loss. People suffering from these symptoms should stop using the hot tub or indoor pool immediately. Corticosteroids may be prescribed, as well as supplemental oxygen for extreme cases. Medical professionals do not agree on whether antibiotics cure hypersensitivity pneumonitis or if it is better to let it improve without any antibiotic treatment.
In order to prevent hot tub lung, hot tubs and indoor swimming pools should always have a sufficient level of sanitizer in the water. Ventilation in the area is also important, to make sure that fresh air circulates and dilutes any endotoxins in the air. Water in spas or pools also needs to be changed regularly and have the correct balance and filtration needed. If a spa has not been used for a while, they should be sanitized before being used again. While being sanitized, all jets should be turned on so that the entire water system comes in contact with the sanitizer.