Beyond the Lungs: The Multisystem Impact of Air Pollution on the Rising Burden of Diabetes, Cardiovascular Diseases, and Mental Disorders in Bangladesh

Almost the entire global population (99%) breathes air that exceeds the World Health Organization (WHO) air quality guidelines (WHO, 2022), contributing to an ~6.7 million premature deaths annually (Types of Pollutants, n.d.). Once regarded primarily as an environmental concern, air pollution is now recognized as a major multisystem determinant of non-communicable diseases (NCDs). Beyond its well-established respiratory effects, accumulating epidemiological and clinical evidence has linked air pollution to cardiovascular, metabolic, immune, and neurological disorders (Brook et al., 2010; Rajagopalan et al., 2018; Schraufnagel et al., 2019). This burden is particularly severe in low- and middle-income countries (LMICs) such as Bangladesh, where rapid urbanization, industrialization, and weak environmental governance have resulted in chronic exposure to hazardous air pollutants. Fine particulate matter (PM2.5), the most harmful ambient air pollutant, consistently exceeds WHO guideline values. According to an analysis by the Centre for Atmospheric Pollution Studies (CAPS), Dhaka (the capital city of Bangladesh) experienced clean air on only 31 of 3,114 days between 2017 and 2025, while air quality was classified as unhealthy on 853 days, very unhealthy on 635 days, and hazardous on 93 days. The highest monthly average Air Quality Index (AQI) recorded during this period was 300 in January 2024, whereas the lowest was 97 in July 2021. These findings are consistent with IQAir reports showing that Bangladesh has remained among the world's most polluted countries, ranking 1st in 2021 & 2023 and 2nd in 2024, with Dhaka ranking as the 3rd most polluted city globally in 2024. Major sources include vehicle emissions, brick kilns, industrial activities, construction dust, and transboundary air pollution, compounded by unfavorable meteorological conditions (World Bank, 2022; IQAir, 2024). Unlike episodic environmental hazards, chronic exposure to PM2.5 causes sustained biological damage through systemic inflammation, oxidative stress, endocrine disruption, and vascular dysfunction (Pope et al., 2004; Rajagopalan et al., 2018). Emerging evidence also implicates neuroinflammation and blood-brain barrier disruption in depression, anxiety, and cognitive decline (Block & Calderón-Garcidueñas, 2009; Braithwaite et al., 2019). Consequently, long-term PM2.5 exposure has been associated with an increased risk of insulin resistance and Type 2 diabetes (T2D), cardiovascular disease, premature mortality, and adverse mental health outcomes (Eze et al., 2015; Liu et al., 2019). Studies from Bangladesh similarly report a higher prevalence of NCDs in densely populated and industrialized urban areas, highlighting air pollution as an important contributor to the country's changing disease profile. The health impacts of air pollution are further amplified by climate variability, socioeconomic inequalities, and weak environmental governance. Reduced rainfall and altered seasonal patterns limit the atmospheric dispersion of pollutants, while disadvantaged populations often experience greater exposure and reduced access to healthcare (World Bank, 2019). These interconnected challenges underscore the need to recognize air pollution as a multisystem health determinant requiring coordinated action across environmental protection, public health, urban planning, and climate adaptation. Without such integrated interventions, air pollution will continue to intensify Bangladesh's growing burden of NCDs and undermine population health, economic productivity, and sustainable development.