What's the difference between BFE & PFE?

According to the industry standards for medical surgical masks for this purpose, specific requirements are set for the filtration efficiency of masks:Mask Particle Filtration Efficiency Tester(PFE)is ≥30%, and Respirator Bacterial Filtration Efficiency (BFE) Tester is ≥ 95%.

Comparison of Mask Particle Filtration Efficiency Tester(PFE) and Respirator Bacterial Filtration Efficiency (BFE) Tester

Mask Particle Filtration Efficiency Tester(PFE) and Respirator Bacterial Filtration Efficiency (BFE) Tester are both evaluation indicators for the filtration of masks. The diameter of Staphylococcus aureus used in the bacterial filtration efficiency test is about 0.8um, and the filtration efficiency test of NaCl particles The 0.3um sol used is slightly larger than that, and theoretically it should be easily filtered. Same as the results obtained in the actual test. After testing 41 batches of medical surgical masks from different manufacturers, it is found that when the PFE of the mask reaches more than 86%, the BFE can reach more than 98% (see attached Table 1) and the test results are relevant (see Figure 2). When the NaCl PFE value of the mask is sufficiently high, the BFE value can also meet the standard requirements.

The correlation between NaCl PFE and the BFE: The correlation between the filtration efficiency of NaCl PFE and the BFE can be further analyzed according to the data in the attached table. The results show that there is a positive correlation between the efficiency of non-oily particles and the efficiency of bacterial filtration.(see Figure 2)

Summary

YY 0469-2011 (Technical Requirements for Medical Surgical Masks) "The technical requirements for filtration rate in the new industry standard are NaCl PFE ≥ 30%, BFE ≥ 95%, of which the NaCl PFE requirement value is lower, and bacterial filtration The efficiency requirement is higher. The test results show that when a mask meets these two requirements at the same time, the NaCl PFE is often much higher than 30%, and the test results are obviously positively correlated. According to the test results, it can be considered When the product has a high NaCl PFE, the feasibility of the special BFE of the particle filtration efficiency can be further considered, that is, when the particle filtration efficiency value (PFE) of the medical surgical mask is higher than the specified value. For example, 85 %, the bacteria filtration efficiency test can no longer be performed, which can not only reduce the risk of the use of pathogenic microorganisms in the laboratory, but also save inspection resources and improve inspection efficiency.