Yes, your air quality depends on it. Indoor humidity and airborne contaminants are hazardous to your health and can be controlled by proper ventilation.
Mold can be caused by high humidity, and indoor high humidity can be caused by numerous factors, such as construction design, climate issues, normal daily activities, open windows, and mechanical ventilation.
Airborne contaminants may stem from chemicals used for construction, appliances that burn gas, poor ventilation while using these appliances, outdoor particulates and allergens.
Proper ventilation is having the right HVAC system, which is conducive to improvement of your air quality, along with regular maintenance and proper duct sealing to minimize all these problems.