Background & Objectives : Hospital indoor air contains a wide range of airborne pathogenic bioaerosols which have a significant impact on health care staff’ health and welfare. The aim of this study was to assess the effects of ventilation system types on occupational exposure of the health care staffs to airborne bioaerosols in the isolation room based on the patient bed arrangements and the standing locations of the health care staff.

 Methods: Personal exposures were measured based on five given types of ventilation system, 2 patient bed arrangements (at a corner and in the middle of the room), and two different standing locations for the health care staff (standing close to the patient’s bed, and down a side section of the bed). For personal sampling, filtration method recommended by th e American conference of governmental industrial hygienists(ACGIH) was used.

 Result: The highest exposure to airborne bioaerosols was observed when the ventilation system was switched off. There were significant decreases in the bioaerosols concentration after using all types of ventilation system (P _value <0.001). The ventilation capacities of 12 air changes per hour showed the best results. No significant differences were found between the bioaerosols concentrations based on the patient bed arrangements as well as the standing locations of the health care staff s (P _value > 0.05).

  Conclusions : The most effective ventilation system for decreasing health care staff’ exposures in the isolation room was associated with supplying of air from a circular grill located on the northern wall and exhausting it through a linear slot located on the southern wall (type 1) with the ventilation rate of 12 air changes per hour.