Don thy Gasmask and never, ever remove it.
Even just wearing a dust mask or two helps a lot.
Chug sleepy cough syrup like a madman, make sure you drink lots of water, eat your vitamins and sleep it off. Might take a few days.
Also wear a Sleeping bag or a blanket when you go to sleep, even if you’ve got a bed.
If you get a gamma gobulin shot that should get rid of it in a few hours or a night of rest if you have enough water to stop being dehydrated. Also make sure you get some hot food.
The Hidden health stat can creep up on you pretty quick-- especially if you’re often cold/freezing or get caught in the rain-- even more so if you get injured.
Also remember to remove your sleeping bag and dust masks while fighting unless you fancy being an Oscar Mayer Wiener.
Mmmm. Meat Flavoured-meat.