European Standard · Respiratory Protection
EN 143 – Particle Filters: Classification and Requirements for Respirator Filters
EN 143 is the European standard specifying requirements, classification and marking for particle filters used with reusable half masks, quarter masks and full face masks to protect against airborne particulate hazards.
1. Scope
EN 143 applies to replaceable particle filters attached to masks meeting EN 140 or EN 136. It classifies filters into P1, P2 and P3 classes based on filtration efficiency, mirroring the protection tiers used for disposable FFP masks but for reusable filter-based systems.
2. Exclusions & Related Standards
- Does not cover disposable filtering half masks with a built-in filter – see EN 149.
- Filters must be fitted to a compatible mask meeting EN 140 (half/quarter mask) or EN 136 (full face mask).
- Gas and vapour filters are covered by separate standards and are not within the scope of EN 143.
- Often selected alongside eye protection under EN 166 when using half masks rather than full face masks.
3. Key Requirements & Marking
Filters are marked with their class (P1, P2 or P3) and optionally R (reusable across multiple shifts) or D (passed the dolomite clogging test). Minimum filtration efficiencies mirror the FFP system: P1 filters at least 80%, P2 at least 94%, and P3 at least 99% of test particles.
4. Testing Overview
Testing includes penetration testing with sodium chloride and paraffin oil aerosols, breathing resistance measurement, clogging resistance for the optional D marking, and mechanical strength testing of the filter housing and connector.
5. Selection Guide
Filter class should match the toxicity and concentration of the airborne hazard, following the same logic as FFP mask selection: P1 for low-toxicity nuisance dust, P2 for common industrial dusts and biological aerosols, and P3 for fine, highly toxic particles requiring maximum filtration efficiency.
6. Inspection, Care and Maintenance
- Replace filters according to the manufacturer’s recommended service life or sooner if breathing resistance increases
- Store unused filters in sealed packaging away from moisture and contaminants
- Inspect the filter housing and gasket for cracks or damage before fitting to a mask
- Do not attempt to clean or wash particle filters as this can damage the filtering media
- Discard filters immediately if they have been exposed to a substance beyond their rated capacity
7. Frequently Asked Questions
What do P1, P2 and P3 mean on a particle filter?
They indicate the filtration efficiency class, with P1 filtering at least 80% of test particles, P2 at least 94%, and P3 at least 99%, matching the protection levels of FFP1, FFP2 and FFP3 disposable masks.
Can EN 143 filters be used on any mask?
No, filters must be compatible with the mask’s connector type and certified for use together, typically confirmed by the mask and filter manufacturer.
How long do particle filters last?
Service life depends on the environment and filter loading, but manufacturers typically recommend replacement after a set number of hours of use or when breathing resistance becomes noticeably higher.
What does the D marking mean on a particle filter?
D indicates the filter has passed an additional dolomite dust clogging resistance test, showing it maintains performance better in heavy dust conditions.
Are P3 filters needed for asbestos work?
Yes, P3 filters are generally the minimum requirement for asbestos-related work, subject to national regulations and a specific risk assessment.