Pugmercs' choice of filter was chosen directly based on research done by Cambridge University in 2013 related to influenza virus capture at a .02 Micron range (1/5 of covid-19 size). Through their results, materials were selected specifically to align with virus capture size and an acceptable range of Pressure drop. To our knowledge and after interviewing HCPs, this has not been done before either based on the combined need, available information, and physical resources.

By selecting air filters with a sub 1 micron range, we were able to include into face mask N95 compliant materials. We verified with suppliers that these ranges were valid using various commercial air filter metrics. Our filters sit at a MERV 15.5 rating.

Merv versus MPR versus FPR rating chart

Although the Industry standard is based on .3 micron as a baseline, with Covid-19 being .1 micron suggestions of viral suggestion must be expanded. While MERV 15 is the standard of Hospital Inpatient Care with the same results of N95 Surgical Masks as the previously mentioned 2013 Cambridge University study, we chose to expand our filter coverage to 15.5 MERV for maximum coverage. Our filter sheath is 100% cotton, per suggestions from CDC and Cambridge University both as secondary filter and impact barrier (to slow rate of airflow incoming or outgoing on filter).