Abstract: ObjectiveTo investigate Legionella pneumophila(Lp)infection status among workers in public places with centralized air conditioning system in southern area of China.MethodsFrom 2008 to 2009,a total of 427 workers in 7 public places with centralized air-conditioning system and the cooling tower water of the system was contaminated by Lp and 435 workers from 14 public places without centralized air-conditioning system were selected.Questionnaire survey and detection of serum Lp1-Lp7 IgG were conducted among the participants.ResultsThe workers in the public places with centralized air-conditioning system had higher IgG levels(median:10.66 U/ml,95% confidence interval 95%CI6.36-17.95 U/ml)than the workers from the public places without centralized air-conditioning system(median:9.50 U/ml,95%CI:4.98-16.35 U/ml),with a significant difference(P<0.05).The multiple stepwise regression analysis showed that after adjustment for gender,age,smoking,alcohol drinking,and history of chronic diseases,whether using the centralized air-conditioning system in workplaces was an influencing factor of Lp infection(b'=0.075,P<0.05).ConclusionThe cooling tower water pollution of the centralized air-conditioning system is one of risk factors for Lp infection among workers in public places.