HEPA is an acronym that stands for High Efficiency Particulate Air. The National Air Filtration Association (NAFA) defines HEPA filters as a filter having a minimum efficiency of 99.97% on 0.3 micrometer particles.
What Are MERV Ratings?Minimum Efficiency Reporting Value (MERV) is an industry standard that measures the overall effectiveness of air filters. As the MERV rating increases the finer the filtration becomes.
The key layer of the mask is the meltblown cloth layer with electrostatic adsorption in the middle. If the static electricity is lost, the anti-epidemic effect of the mask will also decrease.