Filtering face masks (FFM), sometimes referred to as disposable respirators, are subject to different regulatory standards worldwide. These standards define certain required physical properties and performance characteristics to enable the respirators to claim compliance with the respective standard. In pandemic or emergency situations, health authorities often refer to these standards when making recommendations for respirators, such as that certain population groups should use "N95, FFP2 or equivalent" respirators.
This comparison is used to make comparisons between the criteria for masks of this type:
As can be seen in the table below, it can be assumed that masks certified in one of these standards have equivalent properties.
|(EN 149-2001)||(EN 149-2001)||(NIOSH-42C FR84)||(GB2626-2006)|
|Filterleistung||≥ 94%||≥ 99%||≥ 95%||≥ 95%|
|test aerosol||NaCl and paraffin oil||NaCl and paraffin oil||NaCl||NaCl|
|total inward facing leakage (TIL)*,
tested on humans, perform
the respective exercises
|≤ 8% leakage
|≤ 2% leakage
|N/A||≤ 8% leakage
max. pressure drop
|≥ 70 Pa (at 30 L/min)
≥ 240 Pa (at 95 L/min)
≥ 300 Pa (at 160 L/min)
|≥ 100 Pa (at 30 L/min)
≥ 300 Pa (at 95 L/min)
≥ 300 Pa (at 160 L/min)
|≥ 343 Pa||≥ 350 Pa|
|-1180 Pa||85 L/min|
maximum pressure drop
|≥ 500 Pa||≥ 700 Pa||-1180 Pa||≥ 250 Pa|
|flow rate||160 L/min||-1180 Pa||85 L/min|
|requirement for the
leakage of the exhalation valve
|N / A||N / A||-1180 Pa||pressure drop to
0 Pa ≥ 20 sec
|applied force||N / A||N / A||-1180 Pa||-1180 Pa|
A noteworthy point of comparison is the flow rates for the inhalation and exhalation resistance tests specified by these standards. The flow rates for the inhalation resistance test range from 40 to 160 l/min. The flow rates for exhalation resistance testing range from 30 to 95 L/min. In some countries the tests must be performed at multiple flow rates, in others only at the upper or lower end of these ranges. Although this seems to indicate that the standards' requirements for breathing resistance (also called "pressure drop") differ, it is important to understand that the pressure drop across each filter is naturally higher at higher flow rates and lower at lower flow rates. Given typical pressure curves for breathing apparatus filters, the different pressure drop requirements of the standards are actually quite similar. This diagram shows a representative filter pressure drop curve. When a filter is tested at a high flow rate, the pressure drop is relatively high. If the same filter is tested at a low flow rate, the pressure drop is relatively low.
On the basis of this comparison, it is reasonable to consider the FFRs China KN95, AS/NZ P2, Korea 1st class and Japan DS as "equivalent" to the US NIOSH N95 and European FFP2 respirators in order to filter non-oil based particles such as those generated by forest fires, PM 2,5 air pollution, volcanic eruptions or bioaerosols (e.g. viruses). However, before choosing a respirator, users should consult their local respiratory protection regulations and requirements or seek advice from their local health authorities on the choice.
Filter performance - the filter is evaluated to measure the reduction in concentrations of specific aerosols in the air passing through the filter.
The aerosol generated during the filter performance test.
The amount of a specific aerosol entering the tested respirator via both filter penetration and face leakage while a wearer performs a series of exercises in a test chamber.
The amount of a given aerosol entering the tested respirator while the wearer breathes normally for 3 minutes in a test chamber. The size of the test aerosol (mean diameter) is approximately 0,5 micrometres. Pressure drop - the resistance to which the air is subjected on its way through a medium, e.g. a breathing protection filter.