Here is a clear answer from Wikipedia to help explain:High-efficiency particulate air (HEPA), is an efficiency standard of air filter.Filters meeting the HEPA standard must satisfy certain levels of efficiency. Common standards require that a HEPA air filter must remove—from the air that passes through—at least 99.95% (European Standard) or 99.97% (ASME, U.S. DOE) of particles whose diameter is equal to 0.3 μm; with the filtration efficiency increasing for particle diameters both less than and greater than 0.3 μm.HEPA filters are used in applications that require contamination control, such as the manufacturing of disk drives, medical devices, semiconductors, nuclear, food and pharmaceutical products, as well as in hospitals, homes and vehicles.
For everyone's safety, we do not provide returns, exchanges or refunds for airific or the airific Filter 4Pak.
This product is created to capture and contain airborne toxins. Due to this core function returning products creates and unsafe scenario for the handling of these elements and exposes others to germs and viruses.
Each unit is sealed at the factory with plastic safety seal to prevent and contamination enter your airific or airific filter 4Pak.
If refunds are required due to manufacturing issues please review the warrenty card that was provided with your unit and follow instructions for refund there.