Why did this take so long?

[unixronin]

A new refrigerator line from Sub-Zero will use a NASA-designed air filtration system that filters all the air in the fridge every 20 minutes, eliminating bacteria, odors and micro-contaminants, to keep food fresher longer and the refrigerator smelling better.  Supposed to be available this fall, but no pricing details out yet.

Why did it take so long for somebody to do this?  Filtering out mold spores and bacteria seems such an obvious thing to do.