Study on the Concentration and Distribution of the Airborne Bacteria in Indoor Air in the Lecture Theatres at Tianjin Chengjian University, China

The research on distribution characteristics of bioaerosols in the indoor environment had the vital significance in improving indoor air quality, preventing and controlling the spread of the disease related indoor air, especially for lecture theatres which had the characteristic of step height, the more population density, stronger fluidity and the higher risk of infecting some disease. The bioaerosols distribution characteristics of indoor air in the amphitheatre were studied under the condition of the different time and methods. Using natural sedimentation method and air planktonic bacteria sampling method, the airborne bacteria were sampled in typical amphitheatre. The result showed that airborne bacteria concentration by natural sedimentation method was between 209 to 838CFU m-3, while the concentration used air planktonic bacteria sampling method was in the range of 353 to 1932CFU m-3. The mechanism of the two methods led to the difference of sampling results. Using natural sedimentation method, the concentration at 21 o’clock was among 210 ∼ 419 CFU m-3, and the concentration in the next day 9:00 o’clock was at the 52 to 157 CFU m-3 range, this implied that most of the larger particle size microbial particles had fallen to the ground after 12 hours.