Increases in recent years in the quantities of tetra-ethyl lead manufactured for use as an antidetonant, together with the now almost universal employment of this compound in ethyl and Q fluids throughout the world, has greatly enlarged the scope of the industrial hygienic problem associated with the control of the hazards accompanying its manufacture and blending into motor fuel. Since tetra-ethyl lead added to gasoline in the maximum proportion (1:1,260) now allowed by the purveyors of the compound has been demonstrated to be free from harmful effects as far as any potential hazard resulting from the lead compound is concerned,1the hygienic problem is limited to those men who work with the compound prior to its addition to gasoline, and to those who may be exposed to the products of decomposition formed under certain conditions, which will be described presently. In view of the fact that in several reports