AllerAir AirMed 3 PreFilters

1.  Pre-Filter: Can be visually inspected: When both sides are of similar color should be changed, regular household usage would require Renewal 3-5 months You can vacuum every 2-3 months and replace every 6 months if need be.

2.  HEPA Filter: Can be visually inspected: When both sides are of similar color = should be changed, regular household usage would require Renewal 3-5 years

3.  Carbon Filter: Found inside the unit in a canister from a few inches away, smell the exhaust and if an unpleasant sour odor is emitted that is an indication for renewal, regular household usage would require. Renewal 3-8 years

PS: The above estimated time periods all vary and depend, based on your usage and the odors and contaminants in your space. But the above can be used as a general guideline.