The European standard DIN EN 343 regulates the requirements for clothing to protect against rain as part of protective workwear.
This clothing is protective clothing against precipitation, rain, fog and wind at temperatures greater or equivalent to –5 °C. Two performance parameters are specified for this protective clothing:
x = water penetration resistance (water tightness)
Classification into classes 1 to 3 is possible. Class 3 has the highest water penetration resistance and fulfils the highest requirements.
Water penetration resistance (WP) is measured in pascals (Pa) and is the hydrostatic pressure held by a material. The term "water column" is often used, which is then given in millimeters. Both the material and seams are tested.
y = Water vapour resistance (breathability)
Classification into classes 1 to 3 is possible. Class 3 has the lowest water vapour resistance and fulfils the highest requirements.
Water vapour resistance (Ret) is measured in m2*Pa/W and the lower the resistance the better the breathability of the textile. If the garment has a Ret value of class 1, it must carry the warning "limited wearing time" after this number.