EN 343 sets the requirements for clothing protecting against rain, snow and fog. The marking carries two figures (three since 2019) which are independent of one another, and both matter.
The first figure: water penetration
| Class | Hydrostatic head | In practice |
|---|---|---|
| 1 | ≥ 8 000 Pa | Light rain, short exposure |
| 2 | ≥ 8 000 Pa* | Moderate rain (tested after pretreatment) |
| 3 | ≥ 13 000 Pa | Heavy and sustained rain |
| 4 | ≥ 20 000 Pa | Extreme conditions |
The second figure: breathability
The second figure gives the water-vapour resistance (Ret) — and here the logic inverts: the lower the Ret the better. Class 4 means Ret below 25 and the best breathability; class 1 means Ret above 40, effectively non-breathable.
| Class | Ret | Limitation |
|---|---|---|
| 1 | > 40 | Max 60 minutes of active work |
| 2 | 25 – 40 | Max 105 minutes |
| 3 | 15 – 25 | Max 205 minutes |
| 4 | < 15 | No limit |
Those limits are often ignored, but they matter: working hard in non-breathable clothing traps sweat, and the wearer gets just as wet as from the rain — only in warm, saturated clothing, which is more dangerous in the cold.
The 2019 addition: X
The 2019 edition added an optional third parameter, X, denoting a whole-garment rain-tower test on a moving manikin — a more realistic assessment than testing the fabric alone.
