Air quality and respiratory health in low- and middle-income countries: the breadth of inequality

SUMMARY Air pollution is a leading, but under-addressed determinant of respiratory morbidity and mortality in low- and middle-income countries (LMICs). Populations in these regions experience sustained exposure to a complex mixture of pollutants arising from household biomass combustion, traffic emissions from aging vehicles, industrial activities, and increasingly frequent climate-related events, such as wildfires and dust storms. Unlike in high-income countries (HICs), exposure in LMICs is continuous across indoor and outdoor environments, leaving little opportunity for physiological recovery and disproportionately affecting children, women and individuals with pre-existing respiratory disease. The burden includes asthma, chronic obstructive pulmonary disease (COPD), acute lower respiratory infections, impaired lung growth, and premature mortality. Despite growing epidemiological evidence, substantial gaps remain in exposure assessment, surveillance, and mechanistic understanding, particularly in rapidly urbanizing regions. Effective interventions require a multisectoral approach that integrates the transition to clean household energy, stricter vehicle and industrial emission standards, urban planning to reduce exposure, and climate-resilient air quality management. Strengthening air quality monitoring, improving access to respiratory healthcare, and embedding air pollution mitigation within broader development and climate agendas are critical. Addressing air quality in LMICs is not only a public health necessity but also a matter of global equity, requiring coordinated international action, sustained investment, and locally adapted solutions to reduce the respiratory health burden and improve long-term population health.