These garments are used in environments where there is a risk of explosion (ATEX environments). The outer fabric of the garment has to be anti-static (AST).
Annex II, art.2.3 of the ATEX directive 99/92/CE concerning the protection of workers likely to be exposed to the risk of explosive atmospheres says: "Workers must be provided with appropriate working clothing consisting of materials which do not give rise to electrical discharges that can ignite explosive atmospheres."
Therefore the fabric has to divert the charges thanks to conducting fibres in linear form or in the form of a grid. The distance between the conducting fibres in one direction can nowhere be more than 10 mm.
The outer anitstatic layer (AST) has to cover all the other layers (non AST) permanently. The antistatic covering has to be guaranteed in all circumstances. Conducting accessories (zippers, buttons...) are permitted, provided that they are covered with an AST fabric. The labels or retroreflective stripings have to be attached in a permanent way.
The confection also has to respect several criteria.
The garments have to be put on and taken off outside the ATEX environment. The wearer has to fully close his garment and make sure that his earthing is assured (for example by wearing electrostatic shoes that have a resistance of < 10E 8 Ohm on ground that can dissipate the charge).