"Respirator filters are regularly tested by NIOSH during and after use to ensure that they continue to meet certification testing standards." The FDA has not independently evaluated the filtering performance of surgical masks and has not published the manufacturer's test results. In many cases, it is difficult to find information about the filtering test results of fda removal surgical masks. The surgical masks removed by the US Food and Drug Administration (fda), known as surgical N95 masks, are a notable exception to the uncertainty of filtration performance. This is the only surgical mask that includes strict NIOSH standard evaluation. All members of this type of masks have been approved by NIOSH as N95 masks before obtaining FDA approval. The FDA partially acknowledges that the NIOSH filtration efficiency and respiratory resistance test results exceed the requirements of ordinary surgical masks.
In studies comparing the performance of surgical mask filters using standardized airflow, the filter performance proved to be highly variable. When measured using NIOSH certified test parameters, the collection efficiency of mask filters from masks of different manufacturers can vary from less than 10% to close to 90%. The test results required by fda (if any) do not predict their performance in these studies.
It is important to remember that the overall performance of any surface filter depends on, first of all, good filter performance. A face mask or face mask that does not provide a high level of protection if the filter is not good.
Respirator and surgical mask are suitable
Because respirator filters must meet strict certification requirements, the collection efficiency of various aerosols encountered in the workplace is always very high. Recently, there have been concerns that the respirator filter will not collect nanoparticles, but studies have shown that the efficiency of collecting these particles meets NIOSH standards. This is not surprising because the NIOSH test uses small, charge-neutralized, relatively monodispersed aerosol particles and high airflow.
Therefore, the most important aspect of the performance of the respirator certified by niosh is its degree of fit with the face and the degree of leakage around the mask to a minimum. This must be measured for everyone and the respirator they choose. Choosing the right protective mask for a specific workplace depends largely on choosing the right level of protection.Wholesale N95 Mask
The fit of the respirator depends on two important design features:
Is the working mode of the respirator "negative pressure" or "positive pressure"
Type and extent of facial coverage
Respirators operating in "negative pressure" mode require the wearer to draw air into the mask through an air purification device (filter or chemical cartridge) so that the pressure generated inside the respirator is negative compared to the pressure outside the mask. On the other hand, a "positive pressure" respirator pushes clean air into the mask through a fan or compressor, so that the air pressure inside the mask is greater than the air pressure outside the mask. Negative pressure respirators provide less protection than positive pressure respirators because the former is more prone to internal leakage.
The design of the face is also important-some designs are more suitable for the face than others. Half-mask respirators (covering only the mouth and nose) are more difficult to install than full-face respirators (also covering the eyes). The nose and chin are the most difficult facial features to establish a close connection. The fit of a hood, helmet or "loose" mask is highly dependent on the specific design and configuration. For detailed information about the different levels of respirators and their protection levels, please refer to the NIOSH respirator special page and OSHA respiratory protection standards