Help?
 

I have just perchased a Russian/Soviet Gas mask. Its similier to the gurilla mask. It has the filter on the left cheek, the front nozel and a chin exhuast. Im not sure which model this is. I actualy plan on using it, its more for my collection.

My main question is, how would i clean it? Im thinking just using a wet paper towel and wipeing it down. Also how would i be able to find out how old the filter is?