Iran Occupational Health

Background and aims: The current conventional effective elements on transporting or reducing of airborne aerosols and building indoor air quality are natural ventilation systems. Natural ventilation is supplying fresh air and cooling down by replacing ambient air which is one of the effective parameter on social hygiene and health aspect through controlling airborne pathogens and their related nosocomial infections in different part of  life particularly in hospitals; and is known as one of the cost-effective solutions in this field. The aim of this study is investigation of natural ventilation potential in the different ward of Tehran University of Medical Sciences affiliated hospitals. 

Methods: In this cross-sectional study, humidity, temperature, wind speed and room characteristics of 35 wards of 12 hospitals affiliated to Tehran University of Medical Sciences which consisted a total of 269 rooms were investigated, and results were compared with related standards and guidelines. Investigated wards included infectious, blood, gastrointestinal and tuberculosis wards which have importance from airborne pathogens perspective. The correlation between ACH index and altitude, temperature and humidity along with wards classification to airborne and non-airborne sections, and evaluation of their ACH mean were conducted with Kruskal–Wallis and Fligner-Killeen test by R (version 3.2.0) and Excel 2013 software.

Results: The minimum, maximum and average values of wind speed, humidity and temperature in airborn and non-airborn sections were measured as (0 and 2.9 m/s), (13.5% and 40%) and (24 and 30.7 ºC), respectively. Also, the means of ACH in airborne and non-airborne were 20.5 and 31, respectively. In addition, significant relations among the different parameters of study according to the Kruskal–Wallis test were observed (P-value<0.05).

Conclusion: According to the obtained results of present study and comparing the results with related standards (ACH=12) indicated that opening of the doors and windows of rooms have high potential in reducing the nosocomial infection in studied hospitals. Furthermore, more energy costs can be saved by using natural ventilation in different wards.

Key words: Natural ventilation, Infection control, air changes per hour, Hospital