Refers to ASHRAE Research Project RP-531, which has demonstrated the feasibility of recirculation from industrial dust collectors to reduce energy requirements of ventilation systems. Expands the mathematical modelling work of RP-531 to show how recirculation affects both particulate and gas phases. States the results signal that air quality problems can very readily be encountered when collector air, adequately cleaned of particulates, is recirculated.

KEYWORDS: Industrial, feasibility, dust separators, calculating, particles, dust, gases, indoor, air pollution, air, recirculating, health, hazards.