What those like Sylva see as not taken into account is that three billion people, almost 40 percent of the world’s population—what the World Health Organization (WHO) calls “the forgotten 3 billion”—are subject to indoor air pollution caused by these poor fuels, which the WHO calls “the greatest environmental health risk in the world today.” Close to four million people a year die from this indoor pollution, and many more suffer from a wide variety of illnesses. For children, it can mean stunted development.
