What is Filter change interval?

The filter change interval is the time between filter replacements, counted in months, as the manufacturer states it. It shapes both the running cost and the upkeep, because a shorter interval means more filters to buy and more often you have to open the machine and swap the filter. Air Health gives a filter interval of 6 months, Airthereal 6 to 8 months, and Alen Air Purifiers 12 to 15 months.