Attic whole house replacement filters.
Attic furnace filter.
As the merv rating increases the finer the filtration becomes.
With finer filtration fewer airborne contaminates dust particles are allowed to pass through the filter.
Astro guard attic replacement filters air filters inc.
You say you changed the two in the living areas suggesting that you have a dual zone system 2 floors.
Fire hazards can result if there are excess items pressed against the furnace.
Attic replacement and deep pleated air filters utilize 100 synthetic fibers high initial efficiency and will not promote the growth of bacteria mold mildew or fungi in normal operating environments.
Excessive dust and debris in the furnace area will be pulled into the.
However both your furnace and a c share a single filter.
The most common airborne contaminates that these filters are tested against tend to include pollen dust mites mold spores dust pet dander.
Keep the area around your attic furnace clean.