By the time you’re reading this, it might be time to change your air filter. Under the most average circumstances–an average family without any allergies or asthma issues–you should be changing your HVAC system’s air filter about every 6 months. That time may increase or decrease depending on other factors, but it’s never a bad time to ask yourself every once in a while, “Is it time to change the air filter?” Below are a few reasons why you should change an air filter now instead of later.