EN 166:2001
Eyes are among the most vulnerable parts of the body. From sparks and molten metal to dust, chemicals, and electric arcs, hazards are everywhere. EN 166:2001 sets the fundamental requirements for personal eye protection in Europe.
This standard applies to all types of protective eyewear, including safety glasses, goggles, and face shields. It defines how lenses and frames are tested, how they must be marked, and what classifications apply to ensure protection against specific workplace hazards.
Scope of EN 166:2001
EN 166 specifies:
- General requirements for eye protectors
- Testing of frames and lenses
- Markings and symbols that identify protective performance
- Optical quality classifications
It forms the core reference standard for all PPE designed to protect the eyes or face.
Optical Glasses
Protective eyewear is classified into three optical classes based on visual clarity:
| Class | Use | Refractive Power Tolerance |
|---|---|---|
| Class 1 | Continuous use | ± 0.06 dioptres |
| Class 2 | Intermittent use | ± 0.12 dioptres |
| Class 3 | Occasional use | ± 0.25 dioptres |
Class 1 eyewear is required for prolonged work, such as welding or grinding.
Fields of use
Symbols indicate protection against specific workplace hazards:
| Symbol | Protection |
|---|---|
| 3 | Liquid droplets and splashes |
| 4 | Large dust particles (>5 μm) |
| 5 | Gases and fine dust (<5 μm) |
| 8 | Short-circuit electric arc |
| 9 | Molten metal and hot solids |
Mechanical Strength
EN 166 defines impact resistance levels:
| Symbol | Protection | Application |
|---|---|---|
| None | No impact protection | Filters only |
| S | Extra strong (low drop test) | Oculars only |
| F | Low energy impact (45 m/s) | Glasses, goggles, face shields |
| B | Medium energy impact (120 m/s) | Goggles, face shields |
| A | High energy impact (190 m/s) | Face shields only |
| T | High-speed particles at extreme temperatures | Used with F, B, or A symbols |
Lens Markings
Each lens includes markings that specify its protective function:
- 2, 2C, 3 – UV filters (EN 170)
- 4 – Infrared filters (EN 171)
- 5, 6 – Solar protection (EN 172)
- Shade numbers (1.2–16) – indicate filter strength (e.g., welding lenses, sun glare filters)
Example: 2C-1.2 = UV protection with good color recognition, clear lens.
Optional Requirements
- K – Anti-scratch (surface damage resistance)
- N – Anti-fog (resistance to misting)
- R – Enhanced reflectance
- H – Suitable for smaller heads/faces
- G – Radiant heat (mesh protectors only)
Typical Shade Numbers
| Shade Number | Lens Type | Typical Use |
|---|---|---|
| 1.2 | Clear | General safety eyewear |
| 1.7 | Yellow / in-out | UV and indoor/outdoor use |
| 2.5 | Brown / smoke | Sunlight, glare protection |
| 3.1 | G15, smoke mirrored | Strong sunlight |
| 3–11 | Welding filters | Welding tasks (EN 169 / EN 379 apply) |
Why EN 166 Matters
Across industries, eye hazards are constant:
- Maritime & Offshore – protection against salt spray, UV, and arc flashes.
- Petrochemical – shielding from chemical splashes and fine particles.
- Construction – guarding against dust, flying debris, sparks, and molten metal.
EN 166 ensures that eyewear is tested, classified, and marked to give workers the right level of protection for their tasks.