The World Health Organization (WHO) suggests that polluted air contributes to one in eight deaths worldwide, as dirty air causes lung damage, heart disease, strokes and cancer. The WHO also estimates that indoor air pollution in homes in Africa contributed to nearly 600,000 deaths in 2012.35 To measure the extent of the problem, air quality sensors are being deployed in a range of cities to track levels and changes in pollutants. These sensors can also provide early warning of floods.