April 21, 2015 MEMORANDUM FOR: REGIONAL ADMINISTRATORS THROUGH: DOROTHY DOUGHERTY Deputy Assistant Secretary FROM: THOMAS GALASSI, Director Directorate of Enforcement Programs SUBJECT: Evaluating Hazardous Levels of Accumulation Depth for Combustible Dusts The purpose of this memorandum is to provide guidance in calculating the levels of dust accumulations that may be allowed at workplaces for...