I wish I could always put here nice and colorful photos of my lovely hometown, unfortunately Kraków is one of the most polluted city in Europe..
Two things work against Krakow’s air quality: pollution and geographical factors that prevent the dispersal of pollution. The two major sources of the most harmful pollutants are domestic solid fuel furnaces and motor vehicles, but local industry and air-borne pollutants from other parts of Poland and neighbouring countries also contribute.
Geographically, Krakow sits in a valley, which tends to concentrate pollutants, and experiences a low number of windy days, which means pollutants are not readily dispersed.
Clean air activists are focusing on the problem of domestic solid fuel furnaces as a major source of pollution, and one that could be eliminated relatively easily. Only about 10 percent of Krakow’s households use solid fuel furnaces for heating. Unfortunately, these furnaces are also frequently used to incinerate domestic waste, which is probably the leading cause of the most harmful pollutants. The problem becomes particularly visible during the winter heating season – always the period that sees the most extreme particulate and benzo[a]pyrene levels.
More info about this problem you can find here: http://www.krakowpost.com/6285/2015/11/krakows-air-quality-among-the-worst-in-the-world