The mentioned P100 particulate filter approximately corresponds to a P3 filter according to European standards.
- A half mask with a P3 filter has a nominal protection factor of 48.
- A full face mask with a P3 filter has a nominal protection factor of 1000.
This difference already illustrates that the protection is not only determined by the quality of the filter but also by the face seal leakage.
Note that these nominal protection factors are tested in a laboratory. The values should not be used for the assessment of a real workplace.
There are many reasons for not using nominal protection factors for assessing the likely protection at the workplace. The laboratory tests do not represent the activities covered in workplace situations; the laboratory tests only involve a small number of individuals, who cannot represent a significant portion of the population of respiratory protective device wearers in the workplace; the individuals selected for the test panel are likely to be well-trained and are familiar with the test procedures; the standards allow for disallowing people who do not pass the initial screening test needed before the total inward leakage test is carried out.
– European Standard EN 529 – Respiratory protective devices – Recommendations for selection, use, care and maintenance – Guidance document (2005)
For a realistic assessment, it is better to use so-called assigned protection factors, which depend on applicable national regulatory requirements. Typically, these values correspond to the level of respiratory protection that can realistically be expected to be achieved in the workplace by 95 % of adequately trained and supervised wearers using a properly functioning and correctly fitted respiratory protective device.
- A half mask with a P3 filter has an assigned protection factor of 30 (Germany) or 20 (UK).
- A full face mask with a P3 filter has an assigned protection factor of 400 (Germany) or 40 (UK).
If better protection factors are needed, you should use a power assisted filtering devices, which has the advantage that the pressure inside the facepiece may remain above the ambient air pressure.