Study of refrigeration towers associated with community outbreaks of legionellosis

Abstract

OBJECTIVE To evaluate the factors of risk of the risk cooling towers associated to a community outbreak of legionellosis according to its characteristics of maintenance and the quality of the water with the purpose of improving the systems of prevention of this one disease. METHOD To compare the piece of information gathered between the 4 types of cooling towers: control 1, control 2, probable and confirmed. A total of 184 cooling towers have been studied associated to 17 community outbreak of legionellosis of the province of Barcelona (Spain) during the year 2004, of which 112 are control 1, 54 control 2, 8 probable and 10 confirmed. RESULTS The confirmed towers are characterized by: high levels of conductivity, total aerobes, calcic hardness, total solids in dissolution, temperature and turbidity; low levels of chlorine (< 2 ppm); of use hypochlorite as disinfectant in a 10%; greater degree of breach of the revision program and cleaning of the internal elements of the tower (tray, stuffed and separating of drops); degree of performance of the periodic disinfections and the cleaning of deposits of the 100%. A 47% of the investigated towers do not use the previous treatments of the water in spite of diminishing the parametric values of the quantitatives variables. CONCLUSIONS Measures of prevention of the legionellosis would be due to guarantee: a good quality of the water and the pursuit of its quantitatives variables; chlorine levels superior to 2 ppm; the evaluation of the individual risk for each installation; the performance of the 100% of the program of revision of the internal elements of the towers.