Curtis,
Though I can't say I know exactly how you feel, or what you're going through, I can definitely sympathize with you. I lost my grandmother, mother and father all to cancer, and have done a good job raising my kids to not smoke. Though your father's cancer is not tobacco related, the treatments, pain and suffering (for both patient and family) are similar.
My current HF D/C has a 1 micron felt bag that I bought right after I got it about seven years ago. I'm currently awaiting delivery of a canister filter that goes down to .5 micron. When people think of safety, they think of face shields and glasses and guards. Everyone needs to be aware of the hazards of fine wood dust, years from now it could be too late.
My prayers are with you....
Mike