A/HRC/40/55 of solid fuels (e.g. wood, dung, crop residues, coal) for cooking and heating within the home, as well as by burning kerosene for lighting. 19. The primary sources of air pollution vary between and within States. The relative importance of ambient and household air pollution varies depending on the level of wealth and availability of resources. There are significant interactions between the two categories of air pollution, as burning solid fuels indoors pollutes outdoor air. For example, in India, more than 25 per cent of ambient air pollution is from household sources. 3 The adverse health effects of air pollution are highest in low- and middle-income countries where exposures to both ambient and household air pollution are high. 20. Thousands of chemicals can have negative impacts on air quality. The substances that have been the primary focus of abatement efforts to date because of their known adverse health effects are particulate matter (PM), sulphur dioxide, nitrogen oxides, carbon monoxide, ozone and lead. Among the many other air pollutants of concern are benzene, polycyclic aromatic hydrocarbons, dioxins and furans, and mercury. 21. A group of pollutants that must be targeted with great urgency because of their substantial negative impacts on climate change and air quality are called short-lived climate pollutants and include black carbon, methane and tropospheric ozone. 22. Fulfilling the right to breathe clean air will require action at the household, local, national, regional and international levels. In some States, a significant portion of ambient air pollution is transboundary, meaning the source originates in another country or countries. Prominent examples include sand dust from the Sahara and Gobi deserts, haze from agricultural burning in South-East Asia and forest fires. B. Impacts on human health 23. Exposure to air pollution causes a wide range of health effects including respiratory illness and infections, heart disease, stroke, lung cancer and negative birth outcomes (e.g. pre-term birth and low birth weight). A growing body of evidence links air pollution to other health problems including cataracts, ear infections, the onset of asthma in children, chronic deficits in lung function, stunting, diabetes, childhood obesity, developmental delays, reduced intelligence and neurological disorders afflicting both children and adults. 4 24. Fine particulate air pollution is the single largest environmental risk to health worldwide. Consisting of tiny particles that are breathed into the lungs and then pass into the bloodstream, fine particulate matter contains a toxic mixture of soot, black carbon, sulphates, nitrates and heavy metals, varying from place to place depending on the sources.5 25. More than 90 per cent of the world’s population lives in regions that exceed WHO guidelines for healthy ambient air quality, specifically with respect to fine particulate matter, or PM2.5. In other words, over 6 billion people − including 2 billion children − are breathing air that has adverse consequences for their health and well-being.6 26. Together, ambient and household air pollution contribute to 7 million premature deaths annually, including the deaths of approximately 600,000 children.7 This staggering death toll includes more than 2 million people in South and South-East Asia, more than 2 million people in the Western Pacific region (including China), almost 1 million people in Africa, more than half a million in Europe, almost half a million in the Eastern Mediterranean and more than 300,000 in the Americas. Emerging evidence about air 3 4 5 6 7 World Health Organization (WHO), Burning Opportunity: Clean Household Energy for Health, Sustainable Development, and Wellbeing of Women and Children (Geneva, 2016). WHO, Inheriting a Sustainable World? Atlas on Children’s Health and the Environment (2017). WHO, “Ambient (outdoor) air quality and health”, fact sheet, May 2018. WHO, Air Pollution and Child Health: Prescribing Clean Air, advance copy, 2018. WHO, “Burden of disease from the joint effects of household and ambient air pollution for 2016”, May 2018. 5