There are a a variety of signs you should look into house ventilation, such as:
1. Lingering odors
If you have problems getting potent aromas out of your space, you may have a ventilation problem.
2. Stale air
The air in your rooms should feel fresh, but stale sectors mean you may have inferior ventilation.
3. Lots of dust
Dust can develop more frequently in areas with inadequate airflow.