Study On The Concentration Level And Distribution Characteristics Of Indoor Air Microbial In Medical Buildings

As a public building with dense staff,high mobility,and more pathogens,medical buildings must not ignore indoor microbial pollution.To clarify the pollution levels,distribution characteristics and influencing factors of microorganisms in indoor air of different types of medical buildings during winter,based on the previous research of the research group,the concentration of microbial bacteria and fungi in the air in different types of medical buildings in Beijing including hospitals,community health stations,university hospitals and clinics was tested and analyzed by Andersen type six-stage impact sampler in this study during the winter of 2019.At the same time,the indoor air flow rate and CO₂ concentration were tested and the ventilation,personnel and test site were recorded.Then the concentration levels,particle size distribution characteristics and influencing factors of bacteria and fungi aerosols in different places in medical buildings were analyzed.The main conclusions were as follows:1)The indoor bacterial aerosol concentration levels of different types of medical buildings in winter showed small clinics>medium-sized medical institutions>large hospitals,their concentration ranges were 853.48¹898.74cfu/m³,384.84¹543.77cfu/m³ and340.03⁶91.01cfu/m³;fungal aerosol concentration levels had no significant regularity in three types of medical buildings.2)The concentration of bacterial aerosols in 96%of the test areas in large hospitals was higher than that of fungi,the intensity of bacterial pollution was higher than that of fungi,and the concentration of bacterial aerosol in the hospital corridors and registration halls was generally higher than that in other areas.3)The percentage of particle size of bacterial aerosols in the registration hall,emergency room and corridor of large hospitals had the same size law,and the percentage of particle size of fungal aerosols in different test areas of large and medium-sized medical buildings had the same size law.The bacterial aerosols in the hospital are mainly distributed in the particle size range of>1.1?m,and the fungal aerosols were mainly distributed in the particle size range of1.1⁴.7?m.The distribution of bacterial and fungal aerosol particle sizes in small and medium-sized medical institutions was relatively wide.4)The rule of the median diameter of indoor bacterial aerosol in medical buildings in winter was large hospitals>medium-sized medical institutions>small clinics,which were3.28⁵.10?m,3.06³.46?m and 2.42².95?m respectively;there was no obvious regularity in the distribution of fungal aerosol median diameter.5)The measured area of the medical building reached the clean level of bacterial aerosol concentration limit of 1000cfu/m³,fungus 500cfu/m³ and total microorganisms 3000cfu/m³.The overall proportion was 84%for large hospitals,77%for medium-sized medical institutions and 72%for small clinics.The percentage of microbial aerosols entering various parts of the human respiratory system was 69.77%for bronchial tubes,25.20%for nasal cavity and upper respiratory tract,and 5.03%for alveoli.6)The air velocity in the three types of medical buildings was 0.089⁰.182m/s,0.06⁰.18m/s and 0.048⁰.060m/s,the concentration of CO₂ was 1017¹162ppm,528⁹58ppm and 937¹899ppm.There was a significant negative correlation between the concentration of microbial aerosol and the air velocity in large hospitals,and a significant positive correlation between the concentration of CO₂,but no significant correlation was found in small and medium-sized medical institutions.7)Preliminary analysis of the measured sites showed that in the same hospital,the concentration of microbial aerosols in functional areas with a large number of people per unit area was relatively high;the increase in the amount of personnel activity will increase the concentration of microbial aerosols.