Bad weather has people crowded, but people choose to stay because of the comfort and functionality. If there is a small town in the big city, there is probably don't want to come to work in the big cities.
Both air pollution crowded, but people choose to live because of the convenience and functionality as if in a small town with a big city, there would not have come to work in cities.
The polluted air. People crowded, but chose to stay because of comfort and function, if in a small town there's something big cities there wouldn't have come to work in the big city.