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目的分析集中空调冷却塔结构、设置、管理、消毒等环节中影响军团菌繁殖的因素,为有效控制冷却塔军团菌污染提供科学依据。方法于2013年5—9月,采集北京市16家大、中型公共建筑集中空调冷却塔的192件冷却水样品进行军团菌检测,现场勘查冷却塔设置环境、塔体及部件现况、管理及消毒措施、相关设施设备运行维护等情况,以军团菌检测结果为因变量进行非条件logistic回归分析。结果单因素logistic回归显示,冷却水管是否存在死水区、消毒剂投加地点、消毒剂投加频率、冷却塔运行时长及冷却水样品采集时间均对冷却水军团菌检出有影响,阳性率较高(P<0.05);进一步采用多因素logistic回归显示,冷却水管存在死水区(OR=12.987)、消毒剂投加在系统(OR=3.019)、投加消毒剂时间间隔≥2 d(OR=3.390)、采样时间为夏季(OR=4.406)是冷却水嗜肺军团菌污染的危险因素,均有统计学意义(P<0.05)。结论采样季节和消毒措施对冷却塔军团菌污染有影响,可据此制定更为有效的冷却塔军团菌污染控制措施。
Objective To analyze the factors affecting the reproduction of Legionella in the structure, setting, management and disinfection of cooling towers in centralized air conditioners, so as to provide a scientific basis for effective control of Legionella contamination in cooling towers. Methods From May to September of 2013, 192 samples of cooling water collected from 16 large and medium-sized public buildings in Beijing were collected for detection of Legionella bacteria. The site surveyed the cooling tower to set up the environment, tower body and components status, management and Disinfection measures, operation and maintenance of related facilities and equipment, etc. Legionella test results were used as the dependent variables for unconditional logistic regression analysis. Results Univariate logistic regression showed that there was a stagnant water area in the cooling water pipe, the location of disinfectant dosing, the dosing frequency of disinfectant, the cooling tower running time and the collection time of cooling water samples had an impact on the detection of Legionella pneumophila, the positive rate was Multivariate logistic regression analysis showed that there was a stagnant water area in the cooling water pipe (OR = 12.987), disinfectant added to the system (OR = 3.019), disinfectant dosing interval≥2 d (OR = 3.390). The sampling time was summer (OR = 4.406), which was a risk factor for Legionella pneumophila contamination in cooling water, both of which were statistically significant (P <0.05). Conclusion Sampling season and disinfection measures have an impact on Legionella contamination of the cooling tower, so a more effective cooling control strategy for Legionella contamination can be formulated accordingly.