In an international study published by the journal Environment International, the University of Surrey led an international team of air pollution experts in monitoring pollution hotspots in 10 global cities: Dhaka (Bangladesh); São Paulo (Brazil); Guangzhou (China); Medellín (Colombia); Cairo (Egypt); Addis Ababa (Ethiopia); Chennai (India); Sulaymaniyah (Iraq); Blantyre (Malawi); and Dar-es-Salaam (Tanzania).