This part of VDE 0165 is concerned with the identification and classification of areas where explosive dust atmospheres and combustible dust layers are present in order to permit the correct selection of equipment for use in such areas. It sets out the basic criteria by which the ignition hazards can be assessed and provides guidance on the design and control parameters that can be used for the purpose of reducing such a hazard. The basic statements of the standard can also be applied if flammable fibres or fluff can cause a hazard. The standard is to be applied where there may be a risk of explosive dust atmospheres or combustible dust deposits under normal atmospheric conditions. In this standard, explosive dust atmospheres and combustible dust layers are treated separately. Dust, as defined in this standard, is dangerous because it can potentially form explosive atmospheres if dispersed into air by any means. In Clause 4, area classification for explosive dusts clouds is described, with dust layers acting as one of the possible sources of release. In addition, deposits of combustible dusts can ignite and then act as ignition sources for an explosive atmosphere. In Clause 7 other general considerations for dust layers are described. The examples in this standard are based on a system of effective housekeeping being implemented in the plant to prevent dust layers from accumulating. Where effective housekeeping is not present, the area classification includes the possible formation of explosive dust clouds from dust layers. This standard contains an informative Annex with examples for the classification of hazardous areas (Annex A). The responsible body is DKE/K 235 "Errichten elektrischer Anlagen in explosionsgefährdeten Bereichen" ("Installation of electrical equipment in hazardous areas") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.