i use 5 mic filters to filter moss and fish (guppies) out of drinking water at home ,these last about a week before noticable flow loss 17 litres per min to 2litres per min. these filters will still allow bio agents through.
i'm guessing air filters will have about the same performance?
at work i use a dust / gas respirator, paper particle filter and charcoal filter this is rated at 20 mic. it will still allow flu germs in.
in heavy dust i have to replace front particle filter every 4-5 hours.
hope this helps.
N95 for Respiratory protection from infectious diseases
Medical Reserve Corps and CERT in my county are issued bulk quantities of disposable single-use N95 respirators for protection against airborne dust as well as for protection against infectious disease.
The epidemic of SARS in 2002-2003 led to the development of a formal strategy for the containment of emerging respiratory infections that are
transmitted both through contact (requiring barrier precautions), droplets (requiring droplet precautions, i.e., surgical masks), or aerosols (requiring airborne precautions).
This strategy requires use of respirators with at least N95 filtration capability. N95s are minimum acceptable filter efficiency. N99s or N100s may also be used.
It also requires that facilities adhere to all the provisions of the respirator standard (29 CFR 1910.134), including annual fit-testing for respirators that require a face-to-facepiece seal.
Powered Air Purifying Respirators (PAPRs) with loose-fitting hoods or helmets are exempt from the fit-testing requirements. PAPRs may be shared by staff if they are maintained and disinfected in accordance with OSHA regulatory requirements. Consideration needs to be given to their initials costs and maintenance needs.
NOTE: Additional strategies are described in Standard Operating Procedure 7.2.3 Infection Control in the newly revised Emergency Management Program Guidebook.