Effects of voluntarily regulated breathing on airway function, quality of life, and psychological well-being in rural women with biomass smoke exposure: A randomized controlled trial

Objectives: Biomass smoke-induced pulmonary impairment is characterized by a disproportionately small airway disease phenotype that progressively impairs expiratory flow dynamics and erodes health-related quality of life (QOL) and psychological well-being. In rural women in low- and middle-income countries, this condition remains largely unaddressed by pharmacological or rehabilitative intervention. Methods: A two-arm, parallel-group randomized controlled trial was conducted in rural Rajasthan, India (CTRI/2025/05/087248). Sixty women aged 25–60 years with chronic biomass exposure index (≥60) were randomized to a structured 8-week pranayama -based voluntarily regulated breathing technique (VRBT) intervention ( n = 30; 40 min/day, 5 days/week) or a control group ( n = 30). The primary analysis was conducted as a per-protocol completer analysis because no post-intervention outcome data were available for the five participants who discontinued intervention; no post hoc intention-to-treat imputation was performed. Per-protocol analysis included 55 completers (VRBT n = 27, control n = 28; retention 91.7%). Primary outcomes were forced expiratory flow (FEF) between 25% and 75% of forced vital capacity (FEF25–75) and peak expiratory flow rate (PEFR). The World Health Organization quality of life (WHOQOL-BREF) domain scores and depression, anxiety, and stress scale-21 Items subscale scores were analyzed as secondary outcomes. Between-group differences were assessed by analysis of covariance (ANCOVA) adjusted for pre-specified covariates. Results: VRBT produced significant between-group improvements in FEF25–75 (mean change: +0.28 litre per second [L/s]; ANCOVA p = 0.007, partial eta-squared [ηp 2 ] = 0.147) and PEFR (+0.60 L/s; ANCOVA p = 0.014, ηp 2 = 0.121). The WHOQOL-BREF physical domain demonstrated a large between-group effect (ANCOVA p < 0.001, ηp 2 = 0.271), and the social domain improved significantly ( p = 0.011, ηp 2 = 0.129). Stress was significantly reduced ( p = 0.023, ηp 2 = 0.105). The WHOQOL-BREF Psychological domain improved significantly within the VRBT group ( p = 0.002), but did not reach between-group significance. WHOQOL-BREF Environment, Anxiety, and Depression did not differ significantly between groups. Conclusion: An 8-week VRBT intervention produced statistically significant change in airway flow indices, physical QOL, and perceived stress in women with biomass smoke-induced pulmonary impairment. The findings suggest that VRBT may be an effective adjunctive, equipment-free, and culturally accessible rehabilitation approach for managing the multidimensional burden of biomass smoke-related respiratory impairment in rural settings.