The promulgation of 29 CFR 1910.1043 has required extensive engineering controls to reduce work place dust levels to permissible exposure levels. The transport of air laden with fiber, fly and dust from local exhaust ventilation systems to a primary filtration unit and the resultant transport of fine dust to a secondary dust filtration system is described. The three approaches used are: saran screens, condensers and cyclones; and the operating parameters for maximum efficiency.

Secondary dust filtration is necessary if the exhausted air is to be returned directly to process areas or returned indirectly via air conditioning systems. Various secondary filtration design parameters, optimizing system performance to achieve average dust concentrations of 40 µg/m³ or less in filtered air and maintenance required for quality assurance that the system operates as per design criteria are also described.