HEPA filtration is rated at 99.970% efficiency on particle sizes as small as 0.3 microns, more than sufficient to clean air in any room of the house or office. The HEPA filters will actually allow for increased air filtration over the ULPA filters (rated at 99.999% efficiency on particle sizes as small as 0.12 microns) in the same amount of time.
Note: Keep the reusable prefilter that came with the unit. Clean the reusable prefilter.
Inspect filters at least once every six months, or more often if used in an area with higher than average levels of air pollution. Replace filters immediately if the filter life indicator is flashing.