In their daily activities, humans produce many types of emissions that affect the atmosphere. These emissions come, for example, from agriculture and land use, industry, electricity production, transportation and buildings (UNEP 2019a).
Air pollution
Air pollution affects every region of the world (World Health Organization [WHO] 2017; WHO 2018a; WHO 2018b). People in low-income cities are the most impacted. Around 97 per cent of cities in low- and middle-income countries with more than 100,000 inhabitants do not meet WHO air quality guidelines. In high- income countries, that percentage decreases to some 49 per cent (WHO 2018a; WHO 2018b).
Figure 1.3 shows some of these pollutants, how they enter the atmosphere, and their impacts on human health and the environment. Air pollution is the main environmental contributor to the global burden of disease, with impacts that are especially prominent in cities (WHO 2018a; WHO 2018b; UNEP 2019a).
Cities frequently attract young people because of their employment and educational opportunities.
