EN 343
Protective clothing against rain and bad weather
In this European Standard the measured properties of materials and seams of protective clothing and their subsequent classification are intended to ensure an adequate protection level. Water proofness and water vapour resistance are the essential properties to be tested and marked on the label. 
Water proofness is the most important property and it is measured on material of the outer garment layer. Tests are made on new and pretreated fabric samples and on parts with seams.
Some waterproof materials are impermeable to water vapour transmission. However other materials on the market combine water proofness with water vapour permeability. This property expressed by low water vapour resistance enhances sweat evaporation and significantly contribute to body cooling. This is valuable, because it contributes to better comfort and less physiological strain and prolongs the wearing time in certain climatic conditions (see annex A).
Parameters
EN 343 specifies parameters with specific performance requirements.
A: Resistance to water penetration: 1-4, where class 4 provides the best waterproofness.
B: Breathability - water vapour resistance: 1-4, where class 4 provides the best breathability.
C: Impact from above with high energy droplets (optional) Replaced with X if the garment has not been tested.
