Dri-Eaz Primary HEPA 500 Filters for Use with F284 Air Scrubber are 99.97% effective in removing oily aerosol particles as small as 0.3 microns from your environment. Rigid plastic frames preserve the integrity of the filter media. Be sure to replace this filter when the change light turns on or after each job involving mold, sewage or other microbial contaminants. Also replace after use in an environment containing toxic substances, such as asbestos, to prevent cross-contamination. Wear appropriate protective gear when handling contaminated filters, and dispose of them according to local regulations.