There are a a variety of indications you should consider house ventilation, such as:
1. Lasting odors
If you have issues getting potent smells out of your home, you likely have a ventilation problem.
2. Musty air
The air in your house should seem fresh, but stuffy zones mean you may have inadequate ventilation.
3. Disproportionate dust
Dust can get stuck more often in rooms with poor ventilation.