Hi Lee,
Sorry, I can't look up what filter would be best. I gave away the only source of info I had to a friend. Most companies that manufacturer MSHA/NIOSH approved masks make several different types of filters for them. It Depends on what you trying to filter out. Carbon activated filters do typically help reduce smell but aren't good for everything. I suggest contacting a company called Lab Safety Equipment. http://labsafety.com/
They have a great assortment of respirators and filters and should be able to point you in the right direction. Hope this helps, Happy building!