[RKDinOKC]

This is our household experience...

Had allergy problems.

Tried one of those Ozone machines. Recommended by a healthcare professional/family friend.
Didn't seem to help much.

Put in the highest density filters in HVAC. Had to change them about once a month.
Would start sneezing after we first got up, checked the filters and they were filthy, time to change.

Had someone sell me on a Fairfax canister style vacuum.
We had a rainbow, the salesman showed the dirt coming out the exhaust with a bright lite.
Said the dust went thru the water like stones skipping on a lake.
The Fairfax had nothing you could see in it's exhaust. It has a bag, plus two filters, AND a 1 micron filter.
Said it could be used as a hospital grade air purifier, well...except for the noise.

It also cleaned better.
When first got it bought several top vacuums for comparison.
Could vacuum and area with others until they would not pick anything else.
Then go over the area with the Fairfax and it would get more stuff.
Could vacuum with the fairfax and then others and they would not pick anything up.
Well, except for a Hoover, it didn't get any more dirt or dust, but seemed to always de-thread carpet.
Took them all back and kept the Fairfax.

Couple weeks after using the Fairfax noticed we stopped getting dust collecting on things.
Seems a lot of dust was getting kicked up out of the carpet again and again until we got the Fairfax.

We can now go a full 3 months before the filters get dirty and (3 moths is how long the hours of use thing goes on the HVAC), nobody starts sneezing.

Stopped the allergy problems well enough we stopped looking for a purifier.