1.1 General This European Standard specifies general requirements for the dust measurement of electric motor operated tools supplied from mains or from batteries. This standard applies to those tools with and without dust extraction unit where dust such as mineral dust containing silica or wood dust is expected. 1.2 Types of dust Dust is a disperse distribution of solid substances in gases, particularly air, resulting from mechanical processes. According to EN 481 two size categories are to be differentiated: the inhalable dust and the respirable dust fraction. Inhalable dust refers to the entire inhalable portion of the dust through mouth and nose. Respirable dust relates to the portion of the respirable dust which can reach the pulmonary alveoli due to its small particle size.