There are a a variety of indications you might require house ventilation, including:
1. Ever-present odors
If you have trouble getting powerful smells out of your space, you may have a ventilation issue.
2. Stale air
The air in your space should feel fresh, but stuffy spots mean you likely have poor ventilation.
3. Disproportionate dust
Dust can build up more often in areas with inadequate air movement.