Qualitative Evaluation of Laboratory Hoods in Departments Affiliated to Qazvin University of Medical Sciences, Followed by an Interventional Measure

Background and Objective: Various types of chemical and biological agents with different physicochemical properties and health effects are used in laboratories. The present study aimed to qualitatively evaluate the operation of laboratory hoods in the "Campus" laboratories, as well as the Food and Drug Administration affiliated to Qazvin University of Medical Sciences, Qazvin, Iran. Materials and Methods: This study evaluated 19 chemical and 10 biological hoods located in the "Campus" laboratories, as well as the Food and Drug Administration according to the American Conference of Governmental Industrial Hygienists standards in Qazvin Province, Iran. Different factors, such as velocity at the hood mouth, structural specifications, and their accordance with the standards were examined in this study. The data were then analyzed in SPSS software (version 21). In total, seven hoods were found malfunctioned, and a central ventilation system was designed using the velocity pressure method. Results: According to the results, the velocity at the hood mouth was inappropriate in 92.6% of the hoods, and the maximum velocity at the mouth was estimated at 158 fpm. Moreover, obvious leakage was observed in 67% of the chemical hoods, and they were improperly connected to the roof channels using flexible ducts. The result of the velocity assessment in the hood mouth connected to the central ventilation system indicated a 60% increase in the airflow and 11±92 fpm velocity supply in the hood mouth. In order to utilize the air diluting capacities, the ventilation system chimney was installed at the highest point on the building to prevent contaminated air return into the building. Conclusion: The majority of the evaluated hoods were found malfunctioned and unable to control the respiratory exposure. Moreover, the ventilators connected to the hoods were not able to overcome the pressure drop in the discharge flow paths and produced a lot of nois