There are a a couple warning signs you might require house ventilation, starting with:
1. Enduring odors
If you have trouble getting powerful aromas out of your home, you could have a ventilation issue.
2. Stale air
The air in your house should be fresh, but stale areas mean you likely have inadequate ventilation.
3. Built up dust
Dust can build up more often in homes with stifled air movement.