SatPollution gives you the possibility of checking the amount of NO2 concentration across a period of time in different regions of the world, across different dates.
This allows you to check the economical development of a region across the time, how remarkable events cause impacts on the activity of a country, or how weather affects the amount of pollution on a city
All this data is obtained using the Tropomi instrument in the Sentinel 5-P satellite, part of the European Copernicus Program.