This randomized controlled trial evaluated whether performing the same yoga-based breathing exercise program in a salt-cave environment produced different respiratory, functional, physical activity, and quality-of-life outcomes compared with the same program performed in a standard clinical setting in adult smokers. Sixty adult smokers were randomized to either a salt-cave group or a control group. Both groups received a physiotherapist-supervised yoga-based breathing exercise program for 6 weeks, twice weekly, in 50-minute sessions. The intervention content, frequency, duration, and physiotherapist supervision were identical in both groups; the only planned between-group difference was the intervention setting. Spirometric outcomes were assessed at baseline, week 3, and week 6. Functional exercise capacity, physical activity, and quality of life were assessed at baseline and week 6.