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The importance of Fit test

Updated: Mar 2, 2022

Respirators, such as N95 and EN149 FFP2 NR, are designed in a three-dimensional figure. Their edges are close to the face to ensure that air does not enter through the gap between the respirator and the face. Air passes through the filter layer which effectively blocks bacteria and viruses.

Fit test is aimed to measure the degree of match between the user and the respirator through approved precision instrument, as well as giving the data of fit visually. However, this test is not applicable to 2d flat face masks.

Moreover, users can find more suitable respirator model and size by doing fit test.

Fit Test

Wearing EN149 FFP2 NR or US N95 respirator requires a fitting test. According to the EU standard, respirators must pass the 10-person fit test provided by the certifying body. Although Niosh (US certification organization) does not directly require it, OSHA (Occupational Safety and Health Administration of the Ministry of Labor) requires that the products must be tested for fit test upon receiving them.

The Hong Kong Hospital Authority (HA) has issued guidelines to private and public hospitals in Hong Kong on fit test, requiring them to set up a dedicated department to carry it out on all healthcare staff in the hospital using Portacount, a fit test machine. The healthcare staff is required to use the passing-test models.

The score ranges from 0 to 200 and 200+; 100 and above is the acceptable score (pass). The higher the score is, the better the user performs with his/her respirator.

Due to the different shapes of head and face, each person has different results in the fit test of different brands and models of respirators. In addition, most medical staff wear masks for more than 8 hours. Comfort, durability, and long-term experience of wearing these respirators should also be considered as important criteria in choosing respirators.

After wearing the respirator, the user should carry out a fit check. The user should pay attention to whether there is air leakage at the edge of the mask, like fog on eye glasses.


1. World Health organization. (2020, November 13). Technical specifications of personal protective equipment for covid-19. World Health Organization. Retrieved February 3, 2022, from

update : 20220215-Eng

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