If your house is extremely dusty, and assuming that your furnace is not due for its annual cleaning, first clean the air filters on your furnace or change the air filters, if they are the disposable type. 

To clean the filters, spray them from the backside of the filter. The goal is to remove the particles by rinsing them off and not by pulling them through the filter.

If the filters in the furnace have not been cleaned or changed in a long time, they may need to be cleaned and changed again in a few weeks as they might get clogged with the house's accumulated particles they are currently filtering out of the air. 

Once the filters are changed or cleaned, you may need to get your ductwork cleaned. It is recommended that ductwork be vacuumed by professionals every two years particularly if someone in the home is allergic to dust, you own pets or have had a recent infestation of mice.