Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death worldwide, and over 90% of COPD-related deaths occurring in low- and middle-income countries (LMICs). Household air pollution (HAP) - from burning solid fuels such as wood, dung, agricultural crop waste, and coal for energy - is the primary risk factor for COPD in these settings. Biomass-related COPD has a distinct histopathology, phenotype and inflammatory profile when compared to tobacco mediated COPD. Despite the high global burden of biomass-related disease, little is known about the effectiveness of pharmacotherapies for biomass-related COPD; to date, no clinical trials have focused specifically on treatment of biomass-related COPD. This study proposes to assess the health impact of biomass-related COPD and test the effectiveness of low dose theophylline compared to standard therapy among adults with biomass-related COPD in Uganda with the aim to assess whether low-dose theophylline improves respiratory symptoms, decreases the inflammatory profile of serum biomarkers and whether administration attenuates the effect of HAP on lung function. The study additionally aims to assess whether low-dose theophylline is a cost-effective intervention based on the incremental cost-effectiveness ratio and a range of willingness to pay thresholds.