Krakow is the most popular tourist destination and the most polluted big city in Poland as well. This is best visible during winter, when people warming their homes with coal, making the situation even worse.
Warsaw, being the biggest Polish city and the capital of Poland, is one of the most congested cities in Poland. To make things better, Warsaw authorities try to discourage citizens from driving their cars into the city centre, and use public transport instead. One of the ways to make people leave their cars at home, is introducing quite a high parking fares in the city centre.
If you plan to come to Poland with your own car, read our article about main rules that need to be obeyed while driving in Poland