There are a several signs you might require house ventilation, starting with:
1. Lasting odors
If you have issues getting potent aromas out of your space, you may have a ventilation issue.
2. Musty air
The air in your space should feel fresh, but musty areas mean you may have inferior ventilation.
3. Disproportionate dust
Dust can build up more rapidly in homes with inadequate airflow.