Understanding FFP2, KN95, N95, and Other Filtering Respirators

Filtering facepiece respirators (FFRs), often called disposable respirators, follow different standards around the world. Each standard sets out its own rules for how the masks should perform. In times of health emergencies, you’ll usually hear recommendations for models such as N95, FFP2, or their equivalents.

Here are some of the most recognised standards:

• N95 (United States)
• FFP2 (Europe)
• KN95 (China)
• P2 (Australia/New Zealand)
• Korea 1st class (Korea)
• DS2 (Japan)

While the test flow rates for inhalation and exhalation vary between these standards — ranging roughly from 30 to 160 L/min — the overall breathing resistance, or pressure drop, often comes out quite similar. This is because filters behave consistently: higher flow rates create more resistance, while lower flow rates reduce it.​

Understanding Mask/Respirator Pressure Drop

A pressure drop simply means how much resistance the mask material gives to air passing through it.

• Lower pressure drop = air moves through the mask more easily.
• Higher airflow rate = breathing feels more comfortable.

But there’s a trade-off. If resistance is too low, the mask may not filter particles as effectively. That’s why respirator design always looks for balance — enough airflow for comfort, and strong filtration for protection.

Standards	FFP2 (EN149-2001)	N95 (NIOSH-42C FR84)	KN95 (GB2626-06)	P2 (AS/NZ 1716:2012)	Korea 1st Class (KMOEL - 2017-64)	DS2 (Japan JMHLW-Notification 214, 2018)
Filter Performance	≥ 94%	≥ 95%	≥ 95%	≥ 94%	≥ 94%	≥ 95%
Test Agent	NaCl and Paraffin Oil	NaCl	NaCl	NaCl	NaCl and Paraffin Oil	NaCl
Flow Rate	95 L/min	85 L/min	85 L/min	95 L/min	95 L/min	85 L/min
Total Inward Leakage (til)	≤ 8% leakage (arithmetic mean)	N/A	≤ 8% leakage (arithmetic mean)	≤ 8% leakage (individual & arithmetic mean)	≤ 8% leakage (arithmetic mean)	Inward Leakage Measured and Included in User Instructions
Inhalation Resistance - Max Pressure Drop	≤ 70 Pa (at 30 L/min) ≤ 240 Pa (at 95 L/min) ≤ 500 Pa (clogging)	≤ 343 Pa	≤ 350 Pa	≤ 70 Pa (at 30 L/min) ≤ 240 Pa (at 95 L/min)	≤ 70 Pa (at 30 L/min) ≤ 240 Pa (at 95 L/min)	≤ 70 Pa (w/valve) ≤ 50 Pa (no valve)
Flow Rate (Exhalation)	Varied – See Above	85 L/min	85 L/min	Varied – See Above	Varied – See Above	40 L/min
Exhalation Resistance	≤ 300 Pa	≤ 245 Pa	≤ 250 Pa	≤ 120 Pa	≤ 300 Pa	≤ 70 Pa (w/valve) ≤ 50 Pa (no valve)
Flow Rate (Exhalation)	160 L/min	85 L/min	85 L/min	85 L/min	160 L/min	40 L/min
Exhalation Valve Leakage Requirement	N/A	Leak Rate ≤ 30 M L/min	Depressurisation to 0 Pa ≥ 20 sec	Leak Rate ≤ 30 M L/min	Visual Inspection After 300 L/min for 30 Sec	Depressurisation to 0 Pa ≥ 15 sec
Force Applied	N/A	-245 Pa	-1180 Pa	-250 Pa	N/A	-1,470 Pa
CO2 Clearance Requirement	≤ 1%	N/A	≤ 1%	≤ 1%	≤ 1%	≤ 1%
	BUY FFP2 MASKS

*Japan JMHLW-Notification 214 requires an Inward Leakage test rather than a TIL test. Tested on human subjects each performing exercises.

Definitions:

• Filter performance – Measures how effectively the filter reduces concentrations of specific aerosols in the air that pass through it.
  
  
• Test agent – The aerosol generated during the filter performance evaluation.
  
  
• Total inward leakage (TIL) – The amount of a specific aerosol that enters the respirator facepiece through both the filter and face seal leakage while the wearer performs various exercises in a test chamber.
  
  
• Inward leakage (IL) – The amount of a specific aerosol that enters the respirator facepiece during normal breathing for 3 minutes in a test chamber. The aerosol used has a particle size (count median diameter) of approximately 0.5 micrometres.
  
  
• Pressure drop – The resistance air encounters as it moves through a medium, like a respirator filter.

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