The scientists in Tehran wanted to improve air quality by creating a detailed map of pollution levels in the city. They used data from 20 air pollution stations to measure levels of harmful substances like sulfur dioxide and carbon monoxide. By using GIS software, they made a map showing areas with poor air quality. On a bad day in December 2016, only 27.8% of the city had unhealthy air, but without a detailed map, the whole city had to shut down, costing $1 million a day.