Particle filters trap and hold particles (dust, mist, fume, smoke, micro-organisms) from the air flowing through them. Large particles are easier to trap than small ones. These filters can be used against both solid particles and liquid particles (mists, fine sprays and aerosols).
Solid particulate (particles of solid material, including aerosols, dusts, fibres, smokes and fume) examples:
- Asbestos dust
- Engine exhaust particles and fume
- Lead dust and fume
- Stone dust
- Welding fume
- Wood dust
- Fungal spores and parasites
- Bacteria and viruses
- powder coating mix
- liquid jetting
- chrome acid
- cutting fluids
- oil mists
Particle filters are classified according to their efficiency. The filter (or the facepiece it is built into) will be marked with the letter P (for particle) and a number to indicate efficiency, or the level of protection provided.
- P1 = Low efficiency.
- P2 = Medium efficiency.
- P3 = High efficiency.
- NR = Not reusable – Designed for a single work shift (eight hours) and must be disposed of safely at the end.
- R = Reusable.
These filters are designed to remove gases or vapours as specified by the manufacturer.
Gas/vapour filters do not protect against particles, or give any protection against oxygen-deficient atmospheres.
Gas/vapour filters are classified according to their capacity and the type of substance they can be used against. Their capacity refers to how much of the specified contaminant they can hold(as measured in a laboratory test at set conditions):
- Class 1 = Low capacity.
- Class 2 = Medium capacity.
- Class 3 = High capacity.
BS EN 136:1998 - Full face masks. Requirements, testing, marking.
BS EN 143:2000 + A1:2006 - Particle filters. Requirements, testing, marking
BS EN 149:2001+A1:2009 - Filtering half masks to protect against particles. Requirements, testing, marking.
BS EN 14387:2004+A1:2008 - Gas filter(s) and combined filter(s). Requirements, testing, marking.
APF Assigned Protection Factor
BA Breathing Apparatus
CE Conformite Europeene
D Passed dolomite clogging test
FFP Filtering Facepiece- number indicates filter type
FF Fit Factor
HEPA High Efficiency Particulate Air
NPF Nominal Protection Factor
PAPR Powered Air Purifying Respirator
RPD Respiratory Protective Device
RPE Respiratory Protective Equipment
PPE Personal Protective Equipment
SCBA Self Contained Breathing Apparatus
TH Turbo Hood
WPF Workplace Protection Factor
Manufacturers technical helplines
3M Personal Safety Division
Telephone 0870 60 800 60
Alpha Solway Limited
Telephone: 01461 202452
Helmet Integrated Systems Ltd
Telephone 01776 704421
Moldex-Metric AG & Co. KG
Unit 9, Glaisdale Point
Off Glaisdale Drive
Telephone 0115 9 85 42 88