Method of analysing and classifying the environment where explosive atmosphere (dust / gas) may occur, where there may be a risk of ignition and possibly explosion, due to presence of flammable material (dust / gas) mixed with air under normal atmospheric conditions.  The implication of having a hazardous area are that special precaution to eliminate ignition sources need to be taken, e.g. flameproof, explosion protected electrical equipment etc. In order to carrying out Risk Assesment for Combustible Dust you need to consider HAC which has identified in advance.