When you see a marking such as FFP2 NR, FFP3 NR D or FFP2 R D, the letters after the FFP class tell you about the mask’s reusability and clogging-test status.
This guide explains the common NR, R and D markings used with particle-filtering half masks made to EN 149. It does not replace a COSHH risk assessment, competent respiratory-protection advice or the manufacturer’s instructions.
What is an FFP mask?
FFP stands for Filtering Face Piece. FFP1, FFP2 and FFP3 are classes of particle-filtering half mask respirators covered by EN 149. They are designed for particles such as dust, fibres, fumes, smoke and liquid droplets or mists where the specific product is suitable.
FFP masks are not automatically suitable for gases or vapours. Particle filters do not protect against gases or vapours, and they must not be used in oxygen-deficient atmospheres. If the hazard includes solvents, gases or vapours, a different or combination filter may be required.
What do the letters mean?
| Marking | Meaning | What it tells you |
|---|---|---|
| NR | Not reusable | Designed for use during one work shift, then disposal according to the manufacturer’s instructions. |
| R | Reusable | Designed for reuse, provided it remains serviceable and is cleaned, stored, checked and used as instructed. |
| D | Dolomite clogging test | The mask has passed an additional dolomite dust clogging test, indicating improved resistance to filter clogging during that test. |
The letters describe use and test characteristics. They do not replace the FFP1, FFP2 or FFP3 class, and the D mark is not a higher protection class.
NR: non-reusable masks
NR means the mask is not designed for reuse. HSE guidance describes NR filtering facepieces as being disposed of after a single shift, stated as eight hours in HSG53. The mask may need to be discarded sooner if it becomes damaged, visibly contaminated, difficult to breathe through or otherwise unsuitable.
Do not clean, store and reuse an NR mask unless the manufacturer specifically permits that use. Follow the product’s packaging and instructions for safe disposal, particularly where the mask has been used against a hazardous substance.
R: reusable masks
R means the respirator is designed to be reusable. It does not mean that it can be reused indefinitely, washed in any way or used outside the conditions stated by the manufacturer.
Reusable RPE needs a system for inspection, cleaning, storage, maintenance and replacement. Do not use a reusable mask if the facepiece, straps, valves or filter are damaged, contaminated, expired or no longer able to provide a good seal. Follow the manufacturer’s instructions for cleaning and for any replacement parts or filters.
D: dolomite clogging test
D shows that the mask has passed an additional dolomite dust clogging test. In practical terms, this indicates better resistance to clogging of the filter medium during the specified test conditions. A mask marked D may remain easier to breathe through for longer in dusty conditions than an otherwise comparable mask, but this is not a guarantee for every workplace or dust concentration.
D does not mean the mask is reusable, waterproof or suitable for a particular hazardous substance. Check the complete marking and the manufacturer’s technical information.
How to read a complete marking
FFP2 NR
This is an FFP2 particle-filtering mask designed for non-reusable, single-shift use. It is not a gas or vapour filter.
FFP3 NR D
This is an FFP3 non-reusable mask that has also passed the dolomite clogging test. The D mark does not change its NR status.
FFP2 R D
This is an FFP2 reusable mask that has also passed the dolomite clogging test. It still has to be maintained and used within the manufacturer’s stated limits.
FFP class and assigned protection factor
HSE guidance lists the following approximate assigned protection factors for disposable half-mask respirators:
| Class | HSE assigned protection factor | General particle category |
|---|---|---|
| FFP1 | 4 | Lower-level particle hazards where the risk assessment says it is adequate |
| FFP2 | 10 | Higher particle hazards where the risk assessment says it is adequate |
| FFP3 | 20 | Higher-protection particle applications where the risk assessment says it is adequate |
An assigned protection factor is not the same thing as a filter-efficiency percentage or a guarantee of protection. The right class depends on the substance, its concentration, the task, exposure time, the wearer and the way the respirator is used.
Fit matters more than the letters alone
Tight-fitting FFP masks rely on a seal against the wearer’s face. HSE guidance recommends fit testing for tight-fitting RPE as part of initial selection. Different face shapes may suit different mask models, and one mask will not fit everyone.
- Be clean-shaven where the face seal sits. Beards and stubble can prevent an effective seal.
- Carry out the manufacturer’s fit check every time the mask is put on.
- Adjust the nose bridge and straps, and make sure the mask is fitted in the correct order.
- Check compatibility with glasses, goggles, hearing protection, helmets and other PPE.
- Leave the hazardous area if a good seal cannot be achieved.
A fit check is not the same as a formal face-fit test. Workplace users of tight-fitting RPE should follow their employer’s fit-testing arrangements and training.
What FFP masks do not protect against
FFP masks are particle-filtering respirators. They should not be treated as protection against:
- Gases or vapours such as solvent vapour, chlorine or carbon monoxide
- Oxygen-deficient atmospheres
- Atmospheres immediately dangerous to life or health
- Any contaminant or concentration for which the product has not been selected
RPE should be used as part of a suitable control strategy, not as a replacement for ventilation, isolation, dust suppression or other controls. Where the hazard is uncertain, seek competent advice before selecting a respirator.
Example: FFP3 NR
A manufacturer datasheet for the UCFD-P3V identifies it as an FFP3 NR fold-flat mask to EN 149:2001+A1:2009. Its NR marking means it is designed for single-shift use, while its FFP3 class identifies its particle-filtering category. The datasheet also warns against use in oxygen-deficient atmospheres and says the product must be selected, fitted, used and maintained according to the instructions.
Choosing the right mask
Start with the workplace risk or COSHH assessment. Identify the substance, whether it is a dust, mist, fume, gas or vapour, the likely concentration and the required protection factor. Then select a respirator that is both adequate for the hazard and suitable for the wearer, task and environment.
For a broader explanation of FFP1, FFP2 and FFP3 classes, read FFP1 vs FFP2 vs FFP3: What Do They Mean? Browse the Respiratory and Dust Protection collection for available products.
For official workplace guidance, see the HSE guide to respiratory protective equipment at work, HSG53.
Safety reminder
This guide is general information only. The manufacturer’s instructions, product marking, Declaration of Conformity, workplace risk assessment and competent advice take priority. If a respirator is required for hazardous work, users should receive suitable instruction, training and fit-testing arrangements before relying on it.
Last reviewed: September 2026.