Tier-4 was the second-lowest tier ranking a place town or city could get. Nearly all jobs in such a place involved some type of manual labour. If one couldn't work that way, there were other means of making a living, including another type of manual labour.
The jobs in Tier-4 towns were often dangerous, yet they produced items and more for the higher ranking towns and cities. They were essentially factories for their respective countries and the whole world. As such, there was always a dark, thick smog over those towns.
The air was polluted, making the people suffer and it was unfriendly to their bodies just like the people. Just like in all the other cities, there were gangs in this one as well. However, there were more gangs than one could count their hands on. On top of that, if you weren't in a gang for protection, you would soon find yourself in a bloody mess.