Evaluation of Heating, Ventilation, and Air conditioning (HVAC) System Performance in an Administrative Building in Tehran (Iran)

Introduction: One of the factors influencing on indoor air quality of the buildings is performance of HVAC (heating, ventilation, and air conditioning) systems. These systems supply clean and odorless air, with temperature, humidity, and air velocity within comfort ranges for the residents. The aim of this study was to evaluate performance HVAC system in an administrative building in Tehran. .Material and Method: A questionnaire, developed in their research was used to assess the building occupants’ perception about the performance of HVAC system. To evaluate the performance of HVAC systems, air velocities were measured in the diffusers using a thermal anemometer. Moreover, CO2 concentration, air temperature and relative humidity were measured in the whole floors of the building. Air distribution inside the building was evaluated using smoke test. .Results: Most of the studied people complained about the direction of airflow, thermal conditions and cigarette odor. The highest level of carbon dioxide was measured at 930 ppm inside the restaurant. The maximum and minimum air temperatures and relative humidity were measured 28.3-13.8° C and 28.4-23% respectively. Smoke test showed that the air distribution/direction wasn’t suitable in one third of air diffusers. .Conclusion: Improper air distribution / direction was the main problem with the studied HVAC system which could be corrected by adjusting and balancing of the system

Evaluating Bioaerosol Emissions form in different parts of a Sanitary Wastewater Treatment Plant

Introduction: Bioaeroslos released from wastewater treatment plants may contain pathogens existing in the sewage which could endanger the health of workers. The aim of this study was to evaluate the status of bioaerosol emissions form in a sanitary wastewater treatment plant. .Material and Method: This cross-sectional study was carried out in different units of a sanitary wastewater treatment plant. For this purpose, air samples were collected on blood agar and dextro agar in an Andersen single-stage sampler with flow of 28.3 lit/min for 10 minutes. Collected samples were shipped to the lab immediately and incubated for 48 hours. Then, incubated samples were counted for colonies concentration. .Result: Based on the result of this study, the mean density of bacterial and fungal bioaerosols in all wastewater treatment plants were 412.86±23.30 and 53.72±23.99 CFU/m3, respectively. Microbial contamination of the air within a kilometer away from the site (control areas) was 17 times less than its average density. .Conclusion: Wastewater treatment processes can contaminate the air surrounding the plant, particularly with bacteria bioaerosols. Therefore, it is necessary to control the emissions and protect the health of workers against risks arising from exposure to bioaerosols