Stratification of welding fumes and grinding particles in a large factory hall equipped with displacement ventilation

The purpose of the study was to investigate the performance of displacement ventilation in a large factory hall where large components of stainless st eel for paper, pulp and chemical industries were manufactured. The performa nce of displacement ventilation was evaluated in terms of concentration dis tributions of welding fumes and grinding particles, flow field of the suppl y air and temperature distributions. Large differences in vertical stratifi cation patterns between hexavalent chromium (Cr(VI)) and other particulate contaminants were observed. The concentration of Cr(VI) was notably lower i n the zone of occupancy than in the upper part of the factory hall, whereas the concentrations of total airborne particles and trivalent chromium (Cr( III)) were higher in the occupied zone than in the upper zone. The stratifi cation of Cr(VI) had the same tendency as the air temperature stratificatio n caused by the displacement flow field. (C) 2001 British Occupational Hygi ene Society. Published by Elsevier Science Ltd. All rights reserved.