The SmartAir replacement filter set contains both the EPA and activated carbon filters together. It's important to replace both filters.
Germ buildup is a problem for air purifiers, as old spores can start to collect and live there.
All spores caught in the EPA filter are absorbed by the activated carbon filter, and then destroyed from the UVC light.
It's important to replace your filters so ensure the activated carbon filter stays fresh, and maintains its ability to absorb.