Global, regional and national burden of chronic obstructive pulmonary disease and lower respiratory infection attributable to household air pollution and secondhand smoke from 1990 to 2021: an analysis of the Global Burden of Disease Study (GBD 2021).

Background: Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease that can be influenced by a multitude of factors. As the most significant cause of acute exacerbation of COPD, lower respiratory tract infections (LRIs) still result in a heavy global burden in 2021. The 1990-2021 period encapsulates major global shifts, including the energy transition from solid fuels to clean energy in emerging economies and the implementation of the World Health Organization (WHO) Framework Convention on Tobacco Control (FCTC), making it crucial for public health analysis. This study aims to comprehensively evaluate the global, regional, and national burden of COPD and LRIs attributable to household air pollution (HAP) and secondhand smoke (SHS) from 1990 to 2021, and to project future trends using Global Burden of Disease Study 2021 (GBD 2021) data. Methods: We utilized data from GBD 2021, which provided estimates for 204 countries and territories from 1990 to 2021 using independently estimated population denominators derived from 2,026 data sources including censuses and vital registration systems. HAP was defined as exposure to particulate matter from solid fuel combustion (coal, wood, crop residues, or dung), and SHS was defined as involuntary exposure to tobacco smoke in indoor environments (at home, work, or public places). The Bayesian age-period-cohort (BAPC) and Autoregressive Integrated Moving Average (ARIMA) models were employed to project disease burden and evaluate the impact of HAP and SHS on attributable burden. Results: Globally, from 1990 to 2021, age-standardized disability-adjusted life years (DALYs) and age-standardized mortality rates (ASMRs) for COPD declined by 37.00% and 37.12%, respectively. The corresponding declines for lower respiratory infections (LRIs) were 66.35% and 53.62%, respectively. Despite global declines, the burden of COPD and LRI attributable to HAP and SHS remained disproportionately concentrated in low- and middle-income countries (LMICs), particularly among older females for COPD, children <15 years and older adults aged ≥60 years for LRI. The decline in the burden of COPD attributable to HAP is more pronounced than that linked to SHS. Moreover, for both HAP and SHS, their impacts on future COPD burden are projected to be greater among the female population. Conclusions: Persistently high disease burdens still exist among elderly populations and in LMICs. Importantly, HAP and SHS, as major indoor air pollution sources, contribute to the disease burden partially in a sex-specific manner. Otherwise, future COPD burden attributable to both HAP and SHS is projected to be greater in older females and surpass males by 2030. Key interventions include expanding vaccination, promoting clean cooking fuels, and prioritizing indoor air quality alongside tobacco control.