A reason to keep your air filter clean is to maintain healthy air quality. This is particularly important if anyone in your family suffers from allergies or asthma. Dirty air filters worsen the air quality and can exacerbate symptoms. If you have pets, it’s even more important because pet dander will accumulate in the system and then spread allergens throughout the household. It’s an easy fix to replace your filter and prevent air quality from deteriorating. You should replace your filter once a month, or more often if necessary.