Ear plugs are a must for gun battles..

The stench is overcome by having spearmeny oil in your preps and you put a few drops on the out side of a dust mask (you should have many of these) the spearment over powers the smell of death and rot and will prevent the weak from vomiting when in an area over come by the stench of death, rot and or human waste.

Of course this is only a protection as you quickly remove yourself from the are at a cleaner one or if you are forced to handle the dead for body removal.