Please note there is an ADULT size filter and a CHILD size filter.
These activated charcoal filter inserts are made of 5 layers designed to filter particles as small as 2.5 microns. That means it will filter smoke, smog, dust, pollen and other fine particles. A 2.5 micron particle is small enough that it can only be seen by a microscope.
The key is the activated charcoal center layer. Activated charcoal will adsorb chemicals, gases, viruses and bacteria, neutralizing them in the pores of the charcoal. That's why charcoal filters are used in commercial HEPA filters. Charcoal is also used to filter water and is used to filter blood in dialysis machines.
These inserts will last approximately 50 hours of use in a smoky, smoggy or dusty area. Once the filter is clogged with particulate matter, the filter needs to be replaced. However, if you are using it in a relatively clean air environment, you can use the filter for weeks. The charcoal adsorbs and neutralizes germs (like charcoal in a water filter) and doesn't release germs back into the air.
Remove the filter when washing the cotton mask.
*Mask sold separately*
NOTE: The filter is designed to have the same filtration as a KN95 mask. However, the KN95 designation (like the N95 here in the US), can only be applied to a mask. This is a filter. So it cannot be labelled KN95. However, in government certified tests (where random filters were tested 15 separate times in a government approved lab), it passed the KN95 filter test each time. The Chinese government certified test results are viewable as well as the English translation.