Tropical cities are experiencing rapid growth but lack routine air pollution monitoring to develop prescient air quality policies. Here, we conduct targeted sampling of recent (2000s to 2010s) observations of air pollutants from space-based instruments over 46 fast-growing tropical cities. We quantify significant annual increases in nitrogen dioxide (NO2) (1 to 14, ammonia (2 to 12, and reactive volatile organic compounds (1 to 11 in most cities, driven almost exclusively by emerging anthropogenic sources rather than traditional biomass burning. We estimate annual increases in urban population exposure to air pollutants of 1 to 18PM2.5) and 2 to 23 from 2005 to 2018 and attribute 180,000 (95 −230,000 to 590,000) additional premature deaths in 2018 (62005) to this increase in exposure. These cities are predicted to reach populations of up to 80 million people by 2100, so regulatory action targeting emerging anthropogenic sources is urgently needed. A total of 180,000 additional premature deaths are attributable to rapid air quality degradation in fast-growing tropical cities.