holmes air filter

Most replacement options are True HEPA filters. Many listings describe combination filters that pair HEPA with activated carbon and a preliminary fiber prefilter—marketed as 3‑in‑1 or multi‑stage filters.

Listings state the HEPA element captures particles as small as 0.3 microns and is described as removing up to 99.97% of airborne particles at that size.

Replacement intervals vary across listings. Most descriptions recommend replacing filters every 6 months, while at least one listing indicates a 12‑month interval.

Across listings the filters are described as capturing pollen, household dust, mold spores, dust‑mite debris, pet dander, tobacco smoke, fireplace and wood‑burning stove smoke, smog, and various household odors.

Listing details mention materials such as polypropylene, activated carbon (activated charcoal), plastic, cotton, and a fiber preliminary prefilter.

Listings describe multi‑stage constructions. Some advertise 2‑stage filtration (HEPA plus activated carbon) while others list 3‑stage setups that add a preliminary fiber prefilter before the HEPA and activated carbon.