Wunderpad

Carpet sucks.
Allergens, dander, dust mites, anything small enough makes its way through the pile of your carpet and down to the underpad even if you vacuum around the clock. (don't try this at home)
This has led flooring sales in North America to lean more towards tile and hardwood purchases.
It's not the carpets' fault that it sucks, gravity works.

What I propose is a thin double layer of rubber, custom fitted to each stretch of carpeting in a home, to be installed between the carpet and underpad. The upper sheet is perforated and connected to the lower sheet in a six inch grid to keep the upper sheet from ballooning under pressure.
An air intake would take the form of a small corner round that would run the outer perimeter of each room along the lower edge of the baseboards and pass air through a filter system before being forced between the sheets and up through the carpet backing blasting the particles back into the air.
This serves two purposes. It creates a water repellent barrier between the carpet and underpad, but more importantly rids your carpet of these small particles.
The largest of these particles will fall back down to the surface of the carpet where they can be removed through normal vacuuming and the smaller ones will follow air currents to the intakes and be filtered out.