The Wall Street Journal reported last week that 'hot-tub lung' is a new lifestyle ailment. Doctors believe a growing respiratory condition is directly related to the use of indoor hot tubs. When used indoors, hot-tubs with jets give off an aerosol laden with Mycobacterium avium, giving soakers a serious infection or a persistent condition called hypersensitivity pneumonitis, a.k.a. hot-tub lung.

Suffering with flu-like symptoms and fatigue that wouldn't go away, one victim was told his lungs looked like those of a two-pack-a-day smoker for the last 30 years. 'When you sit in the hot tub and turn on the jets, you are sitting right in a mist that contains the bacteria in droplets perfectly sized for traveling into your lungs,' says Gwen Huitt, an infectious-disease specialist at Denver's National Jewish Medical and Research Center.

Diagnoses are rising along with in-home hot-tub sales. Hot tubs were an estimated $4 billion industry in 2001, with about 375,000 tubs sold. Manufacturers recommend the hot-tub room should be well ventilated, and the filters cleaned and water treated often. Some doctors with hot-tub lung patients say they believe tubs weren't cleaned or maintained adequately.

Health clubs and spas are especially at risk and should immediately eliminate use of indoor hot tubs with poor ventilation. Erik Hansen, a former triathlete and a fitness trainer in Boulder, Colo., lost some of his long-distance running ability and had a fever and sweats at night for eight months. His health club lost 12 clients who got hot-tub lung and quit.