I am leaving in five minutes to go to a ballgame - Rangers vs. Yankees.
Just some quick thoughts. I will respond with more information later.
We have had this discussion before on particle size vs. allergic reactions. I have to admit that you have convinced me that sub-micron allergen fragments can cause an allergic reaction in some people. However, you need to be careful not to generalize your reaction to allergens as the reaction of the standard allergic person. Different people have different thresholds.
You are dealing with a particularly nasty allergen - cat dander. This can cause a major reaction in sensitive people with just a few grains of exposure. I don't think it is realistic or necessary for most allergic people to need a 1000 Cleanroom to be comfortable.
MERV 11 filters pull out about 30% of the particles at 0.3 microns and about 35% of the particles at 0.5 microns. Frankly, I was surprised that the particle counts at 0.3 microns were so low in my office. I think a 60% reduction at this particle size is pretty good and I would contend adequate for most allergic individuals.
Have a great Memorial Day! Wish me luck.