Ski powder from dawn till dusk, grab a beer, and head inside to the tub for a soak? Not so fast. New findings suggest you rethink your day's finale. Indoor jacuzzis can bathe lungs in mist laden with mycobacterium avium complex, a nasty bug that causes hypersensitivity pneumonitis, or so-called Hot Tub Lung. Those infected suffer from flu-like symptoms and fatigue. M.D.'s at the National Jewish and Mayo Clinics in Minnesota, the frothy frontier of Hot Tub Lung science, advise-drum roll, please-heading out-of-doors for your next soak.