Is loot quality affected by location?

Is the quality of the weapons, attachments, and gear you find affected by the area that you find it in?

Yes. But there is no real information available about how the loot spawn system works. As the spawning is made by the server so there will be no data mining data.

But by experience it is quite obvious. Especially in squad games you will be able often able to loot areas without competition (in squad games the players are not that much scattered all around the map). ShatterNL map is quite good but not percent. For example in Yasnaya Polyana the loot on the east (hospital and police station) is significant better than the loot in the north-west part of Yasnaya Polyana