Abstract: ObjectiveTo assess the effect of cleaning and disinfection on centralized air conditioning ventilation systems.Methods11 air conditioning ventilation systems in 5 hotels were sampled and investigate based on 5 Hygienic assessment citerion of cleaning and disinfection of public centralized air conditioning ventilation system6.ResultsMeadians of dustvolume,aerobic bacterial count and fungus countin the dust,aerobic bacterial countin ventilation air were decreaed from 29.83 g/m 2,40 CF U/m 2,7 CFU/m 2,1194 CFU/m 3 to 0.25 g/m²,0 CFU/m²,0.2 CFU/m²,346 CFU/m³,respecticely after the cleaning of the systems.The fungus count median in ventilation airincreased from 283 CF U/m 3 to 848 CF U/m 3 but no significant change in PM 10 was detected.ConclusionThe cleaning and disinfection of centralized air conditioning ventilation systems have active effect on air hygiene quality,but the use of the disinfectant and the profesional training should be considered.