Dilution versus displacement ventilation - environmental conditions in a garment sewing plant

This paper compares the practice of dilution ventilation (DILVENT), which ideally requires perfect mixing, with displacement ventilation (DISPVENT), which involves fresh air displacing contaminated air without mixing. Keeping DILVENT as a reference the approach of intervention was used to estimate the potential of DISPVENT for improving environmental conditions in a garment sewing plant. Air exchange efficiency of DILVENT came to 49%. DISPVENT improved the efficiency lo a level of 57%. At workstation level DISPVENT improved air renewal by a factor of 1 .3. DJSPVENT reduced exposure to nonrespirable particles by a factor of 1.6-2 .8. Exposure to respirable dust was reduced, but formaldehyde concentrations were left unaffected. DISPVENT improved conditions for control of bystander exposure by a factor of 7.7. DISPVENT improved thermal conditions. Draft risk was reduced by a factor of 1.9. It is concluded that DISPVENT has potential for improving environmental conditions in industry.