Around 3.1 billion people, about 43 per cent of the global population in 2014, depend on burning fuels such as wood, crop residue, dung, coal and kerosene to cook their food and heat and light their homes (World Health Organization [WHO] 2016a). These fuels are the dominant source of BC and OC emissions globally and a major source of primary PM, polycyclic aromatic hydrocarbons (PAHs), CO and CO2 emissions (Hoesly et al. 2018). Globally, exposure to residential smoke is one of the largest environmental health risk factors (Cohen et al. 2017). Lack of access to clean household energy is most severe in low- and middle-income countries, but the use of polluting fuels takes place in high-income countries and in urban as well as rural areas. Women and children are the most exposed to household air pollution, and also bear the greatest burden of gathering or procuring the fuels (WHO 2016b). Improving access to cleaner stoves and fuels (including wood pellets, liquid petroleum gas, natural gas, and sources of electricity) has been identified as a global priority, and although progress is being made, many challenges remain (Global Alliance for Clean Cookstoves 2014; WHO 2016a) (see Section 12.2.3).
The energy demands of the built environment (primarily the construction, heating, cooling, and lighting of residential and commercial buildings) account for a large fraction of GHG emissions in countries with developed economies and some cities in developing economies. Improving the energy efficiency of buildings and cities is necessary to meet global goals for GHG mitigation and to achieve co-benefits for air quality. These improvements require policy approaches such as building standards, labelling and rating systems, land-use planning, tax incentives, financing, voluntary commitments, awareness and education.
