HEPA filters were originally designed in the 1940s as a way to prevent the
spread of radioactive contaminants on plants and living organisms. Today, we are using HEPA filters to clean out our air. HEPA ratings are applicable to any air filter that is capable of removing up to 99.97% of particulates 0.3 microns or larger. On the other hand, activated carbon is used in controlling odors, chemicals, and gases. The NL5000 air purifier by Surround Air utilizes both of these purification methods, and the NL5000-Filter is the replacement HEPA and carbon filter for this air purifier. In order to ensure proper particulate and odor control, regularly replace the HEPA/Carbon filter in your Surround Air NL5000 every 6-12 months.