A KN95 mask is a half face, air purifying, particulate respirator that has met the Chinese GB2626-2006 performance standards for these devices. These standards are broadly equivalent to those set by the Nartional Institute For Occupational Safety & Health (NIOSH) in the US. Broadly, they require KN95 Masks to achieve the following:
A filtration rate of at least 95% of NaCl sized particles;
Inhalation resistance of not more than 350 Pa and exhalation resistance of not more than 250 Pa. The flow rate of particles used in this assessment should be 85 L/min.
In addition to the above standards, GB2626-2006 standards require KN95 Masks to “be a tight fitting with face, and be free from deformation during the service life”.
A KN95 mask is also required to demonstrate minimum performance standards where TIL (Total Inward Leakage) is required. Total Inward Leakage refers to the amount of contaminated air leaking through the seal between the wearer’s face and the edges of the respirator. This is consistent with the requirement mentioned above that the KN95 masks should be “tight fitting with face”.
There are also labelling requirements – a KN95 respirator should bear the number and year of publication of the standard to which it is subject. It should also bear the type and grade of the filter elements (e.g. “KN95 ” in this case).
Finally, a KN95 mask with an exhalation valve is subject to leakage performance requirements in respect of the valve:
– depressurization to 0 Pa;
>= 20 seconds with force applied to be -1180 Pa; and
CO2 clearance to be not more than 1%.
The masks in this section do not have exhalation valves, so these standards do not apply to them.