Abstract： Objective To monitor and evaluate the airborne microbial pollution in the confined environment of the 480 m saturation diving chamber and to provide evidences for a reliable evaluation of the health hazard caused by microbes in the chamber environment,as well as for the development of scientific intervention measures.Methods The level of microbes in the environment was measured with the natural sedimentation method,the growing features of indicator microbes were screened with selected medium,types of isolated strains were identified with the VITKE2 system,and airbome microbial contents in the chamber were evaluated with the General National Indoor Microbe Pollution Evaluation Standards.The effect of the environment on the related biological features of the virulence of Pseudomonas aeruginosa,the dominant pathogen in the chamber was monitored by means of the growing curve and motor ability.Results As measured in the experiment,the level of airborne microbes in the saturation diving chamber was 3.9 - 8.4 times higher than that of the national evaluation standards.Microbial types were dominantly human origin pathogens.The growth and motor ability of the prevailing Pseudomonas aeruginosa were enhanced,when compared to the control groups.Conclusions Microbial pollution in the 480 m saturation diving chamber was serious,heliox saturation could induce or enhance the virulence of Pseudomonas aeruginosa,and pathogenic microbes were a potential health hazard to divers in the hyperbaric environment.