Despersion and survival ofLegionella in air

From the time of the report of the Philadelphia outbreak in 1976, the airborne contamination of patients through cooling towers had been suspected although never truly corroborated. Since then, contamination through different air conditioning systems or cooling towers has often been implicated in both epidemics and endemics as well as in sporadic cases. Whatever the conditions, contaminated water present in the different air conditioning systems remains the main source of infection. From the contaminated sites an aerosol occurs. The infectivity of the aerosol is linked to the size of the droplets (d≥μm).