As a qualified aircraft engineer I am naturally familiar with the phenomenon whereby air forced through a narrow gap increases its velocity, and have wondered for some time whether the vacuum cleaner might be contributing to the "asthma" problem.
One day, I used a vacuum cleaner when the sun was shining, and noticed that the exit point for the air was throwing up clouds of dust. Half an hour later, I was (as usual) racked with wheezing.
I have since discovered that for the trouble of opening doors and windows when using a vacuum appliance, wheezing fits become a thing of the past, so the only certain answer, surely, is for houses to have vacuum exit points set into the walls, so no dust can be released back into the house.
As for asthma being related to moving house, the answer is simple. People moving either take their old, dusty carpets with them or else install new, fluff-prone carpets, both of which require vacuuming.