Every three to five years is recommended, depending on a variety of factors, including the age of your home, number of pets, family members with allergies, or if a smoker resides in the home.  Older homes allow more contaminants and pests in from the outdoors and can be more susceptible to moisture problems that can lead to mold issues.  On the other hand, newer homes are tighter with new building technologies and can “breathe” less than old homes, holding the contaminants created inside from escaping. So, even if your home is relatively new, consider regular air quality checks.