Respiratory protection standards guide: filter colours, FFP classes and device standards

Choosing respiratory protection starts with two questions: is there enough oxygen, and what is the contaminant? Filtering devices only clean the air; they do not supply oxygen. So before reading the filter codes, you need to know whether the environment is suitable for a filtering device at all.

How to read the diagrams

• Combined filter code: the letter shows the gas group and the digit next to it the capacity class. P3 after the dash is the particle filter. The example filter is tested against organic and inorganic gases, acid gases and ammonia combined.
• Colour bands: each gas group has a colour: A brown, B grey, E yellow, K green, P white. Mercury and nitrogen oxide filters have two-colour bands and a limited service time.
• Particle classes: for FFP masks, the class covers both filtration and total inward leakage. An FFP3 mask requires at least 99% filtration and at most 2% inward leakage. Reusable masks are marked R and single-shift masks NR.
• Selection order: first oxygen, then the type of contaminant, and finally the concentration and duration. In an environment that may lack oxygen, a filter is useless; breathing apparatus is needed. There is no work filter for carbon monoxide, only escape devices.
• Device standards: filtering facepieces, half and full face masks, filters, powered filtering systems and self-contained breathing apparatus are certified to separate standards. For full face masks in industry, at least class 2 is required.

With tight-fitting masks, protection depends on the mask sealing properly against the face. We explain why face-fit testing is needed in our HSE INDG479 article.

Short selection checklist

1. Check whether oxygen deficiency is possible; if it is, choose breathing apparatus rather than a filtering device.
2. Identify the contaminant: a P filter for dust, fume and mist; the matching letter for gas and vapour; a combined filter if both are present.
3. Set the filter class and mask type (half or full face) according to the concentration and exposure time.
4. Have users of tight-fitting masks face-fit tested.
5. Plan filter changes and mask care according to the manufacturer's instructions for use.

This guide is for general information. For exact requirements and test methods, the current text of the standard and the product's instructions for use apply.