Fresh air is good for you.
Ventilation removes indoor air and adds outside air to dilute the overall level of allergens.
Exhaust fans in the kitchen and bathrooms will help remove odors and moisture, but they must be vented to the outdoors to work properly. A clothes dryer, attic and crawl space should also be vented outdoors. HVAC help . Before you start using any heating or cooling appliances, have them inspected and cleaned by a professional. If, as part of your forced-air system, return vents are located in hallways, be sure to keep doors open to rooms without return vents.