Characteristics of Spatial Distribution of Bacterial Aerosols Produced by Fountain

Abstract

To illuminate the spatial distribution of bacterial aerosols produced by fountain, sprinkler test was conducted in this study. Escherichia coli NK5449 was used as the test strain, and bacterial aerosols were sampled by Anderson six-stage air sampler at different sites around the sprinkler. The concentration and particle size distribution of bacterial aerosols and the correlation between droplet diameter and bacterial aerosols concentration were analyzed. The results showed that the concentration of bacterial aerosols ranged from (38±15) CFU·m-3 to (676±92) CFU·m-3 in the space of 0.75 m to 1.75 m from the ground and 0.5 m to 3 m away from the sprinkler. The bacterial aerosol concentration decreased along with the increase of the height and the distance between the sampling site and the sprinkler,and had significant negative correlation with droplet diameter(P<0.05). With the increase of the distance to sprinkler, the proportion of bacterial aerosol particles with size of larger than 4.7 μm decreased at first and increased subsequently; while the proportion of bacterial aerosol particles with size between 2.1 and 4.7 μm increased firstly and then decreased. The bacterial aerosol particles mainly existed in the part with size between 1.1 and 4.7 μm at sampling sites more than 0.5 m away from the sprinkler. It indicated that bacterial aerosols with small size may be inhaled by people far away from the fountain, and the risk should not be ignored.