There are a few indications you should look into house ventilation, including:
1. Persistent odors
If you have problems getting potent smells out of your house, you may have a ventilation issue.
2. Stuffy air
The air in your house should seem fresh, but stale spots mean you likely have issues with ventilation.
3. Disproportionate dust
Dust can get stuck more frequently in homes with inadequate airflow.