Microbial Indoor Air Quality of Public Places in a Semi-dry City in Iran

摘要

Majority of people spends 90% of their time in indoor; therefore, quality of indoor air is of great importance from health viewpoint. Because of exposure to bioaerosols in indoor and the proven relationship between them and a wide range of undesirable health effects, the present study is aimed to surveying microbial indoor air quality in some of public places of Gonabad City, Iran. The study was carried out in spring 2015 and bacterial and fungal bioaerosols were measured. The bioaerosol samples from each location (municipality building, students? dormitory, public library and hospital) were collected in morning and afternoon from randomly selected spots. Results of measurements of each sampling occasion were reported as mean values. Samplings were done using active Zefon A6 Inpacter sampler at 1.5 height from the floor (normal respiratory height). Totally, 192 samples (96 bacterial and 96 fungi with replication) were collected. Afterward, the bacteria and the fungi were determined based on microbiology tests. Effects of the environmental factors (temperature and relative humidity) on concentration of bioaerosols were also taken into account. concentration of the bacteria and fungi varied in the range 13-813 CFU/m3 and 0-288 CFU/m3 respectively. Air quality in waiting hall of the hospital was the lowest quality with mean bacterial and fungal concentrations of 296.1 and 105.4 CFU m-3, respectively. In addition, air quality in the public library and municipality building was the highest quality with mean concentration of bacteria and fungi 60.6 and 37.8 CFU m-3, respectively. Data analyses showed that there was a direct significant relationship between concentration of bacteria and air temperature (p<0.01). In addition, there was a significant relationship between concentration of bacteria and fungi (p<0.01). The findings also highlighted a significant relationship between concentration of fungi and relative moisture of the air (p<0.05). Taking into account the significant relationship between concentration of bioaerosols and background factors such as temperature and humidity using effective air conditioning system to control temperature and humidity of the air, detecting potential contamination focus points and temporary factors effective on bioaerosols in indoor appears to be effective on improving quality of indoor air. These measures, in turn, result in decrease in concentration of bioaerosols and pathological bioaerosols in particular.