There are a a couple signs you need house ventilation, starting with:
1. Stubborn odors
If you have problems getting potent odors out of your space, you likely have a ventilation issue.
2. Stuffy air
The air in your home should be fresh, but musty zones mean you might have insufficient ventilation.
3. Disproportionate dust
Dust can get stuck more often in homes with stifled airflow.