Cheap Sensors Provide Missing Air Quality Data in African Cities Calibrated low-cost sensors in Kinshasa and Brazzaville provide new information on pollution and help scientists model a way to improve access to air quality data. Two capital cities—Kinshasa and Brazzaville—on opposite banks of the Congo River. Brazzaville (the capital and largest city of the Republic of the Congo) is on the north side of the river, and Kinshasa (the capital and largest city of the Democratic Republic of the Congo) is on the south side. Credit: NASA’s Marshall Space Flight Center, CC BY-NC 2.0 By Carolyn Wilke 11 May 2021