喷泉产生的细菌气溶胶空间分布特性

Characteristics of Spatial Distribution of Bacterial Aerosols Produced by Fountain

为阐明喷泉产生的细菌气溶胶空间分布特性,利用大肠杆菌NK5449作为试验菌株,通过喷泉喷洒试验,使用安德森六级空气采样器采集喷泉周围空间的细菌气溶胶,研究各级细菌气溶胶的浓度和粒径分布特征和变化规律,并分析其与液滴直径的相关性.结果表明,在高度0.75~1.75 m,距离喷头0.5~3 m的范围内,细菌气溶胶总浓度在(38±15)^(676±92)CFU·m-3之间,并随着高度的增加和与喷头之间水平距离的增大而逐渐降低,且与液滴直径呈显著负相关(P<0.05);随着与喷头水平距离的增大,粒径大于4.7μm的细菌气溶胶粒子所占比例出现先降后升的变化趋势;而粒径在2.1~4.7μm之间的粒子所占比例则是先升后降.与喷头水平距离0.5 m以外的各点,细菌气溶胶粒子的粒径大都集中在1.1~4.7μm范围内.距离喷泉较远处的人吸入小粒径细菌气溶胶的风险不容忽视.

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.