The global burden of disease from ambient air pollution is substantial (nearly 8% of all deaths), and increasing with time—largely due to increases in fine particulate matter (PM2·5) and the number of deaths from non-communicable diseases, especially in large low-income and middle-income countries (LMICs) experiencing population growth and ageing.1 Increased awareness of air pollution as a major global public health issue is reflected in the inclusion of air pollution-related mortality and morbidity in targets to meet the health-focused Sustainable Development Goal.