"Krakow is one of Europe's top tourist destinations and attracts millions of visitors each year to soak up its history, culture and architecture. But its appeal wanes during colder months when another prominent feature of the Polish city is on display: air pollution."

"Environmental officials say Krakow's air is among the most polluted in Poland, which in turn, has the most polluted air in the European Union."

"And what's the source of the smog hanging over the city during colder months? It's not Polish industry, but rather residents who burn coal to keep warm."