- "N" if they are Not resistant to oil. (e.g., N95, N99, N100)
- "R" if they are somewhat Resistant to oil. (e.g., R95, R99, R100)
- "P" if they are strongly resistant (i.e., oil Proof). (e.g., P95, P99, P100)
This rating is important in work settings where oils may be present because some industrial oils can degrade the filter performance to the point that it does not filter adequately. Thus, the three filter efficiencies combined with the three oil designations lead to nine types of particulate respirator filter materials. It should be noted that any of the various types of filters listed here would be acceptable for protection against pandemic influenza in workplaces that do not contain oils, particularly if the N95 filter type was unavailable due to shortages.
Replacing Disposable Respirators
Disposable respirators are designed to be used once and are then
to be properly disposed of. Once worn in the presence of an
infectious patient, the respirator should be considered potentially
contaminated with infectious material, and touching the outside of
the device should be avoided to prevent self-inoculation (touching
the contaminated respirator and then touching one’s eyes, nose, or
mouth). It should be noted that a once-worn respirator will also be
contaminated on its inner surface by the microorganisms present in
the exhaled air and oral secretions of the wearer.
If a sufficient supply of respirators is not available during a pandemic, employers and employees may consider reuse as long as the device has not been obviously soiled or damaged (e.g., creased or torn), and it retains its ability to function properly. This practice is not acceptable under normal circumstances and should only be considered under the most dire of conditions. Data on decontamination and/or reuse of respirators for infectious diseases are not available. Reuse may increase the potential for contamination; however, this risk must be balanced against the need to provide respiratory protection. When preparing for a pandemic, employers who anticipate providing respiratory protection to employees for the duration of the pandemic should consider using reusable or elastomeric respirators that are designed to be cleaned, repaired and reused.
