The Risk of Exposure to Infectious Bacterial Bioaerosols in Different Hospital Wards: A Case Study

Background: Biological aerosol particles smaller than 10 microns in diameter are among the health concerns in hospitals since they remain in the air for a long time and are infectious and easily transported. We aimed to investigate the concentration of Escherichia coli and Staphylococcus aureus bioaerosols and evaluate their risk in the indoor environment of different wards of Khatam al-Anbia hospital, Jask, Iran, in 2020. Methods: This descriptive-analytical study was performed by collecting and analyzing 50 samples from seven different hospital wards. The active sampling of bioaerosols was performed according to the standard method of the National Organization for Occupational Health and Safety and by a pump with a flow rate of 28.3 L/min for 10 minutes. Blood agar and eosin methylene blue were used to detect bacteria. Then, the Monte Carlo simulation technique was used to assess the microbial risk. Results: The concentration of S. aureus in different wards of the hospital was 4.81 to 18.11 CFU/m3 . The lowest and highest concentrations of S. aureus were in the operating room and general emergency wards, respectively, while the highest and lowest concentrations of E. coli were in the inpatient wards (0 CFU/m3 ) and infectious emergency ward (21.22 CFU/m3 ), respectively. The highest and lowest daily risk of S. aureus was observed in the neonatal and general emergency wards (8.03×10-4 and 3.02×10-4), respectively. Moreover, the lowest and highest daily risk of E. coli was found in the neonatal and male inpatient wards (zero and 7.21×10-3), respectively. Conclusion: In some hospital wards, the concentration and infection risk of E. coli and S. aureus were found to be higher than the acceptable value. Since high concentrations of airborne bacteria can play an important role in producing nosocomial infections in patients and staff, it is necessary for hospital officials to take corrective measures in equipment control, use proper ventilation systems in the wards, and closely monitor the disinfection process.