Literature
Literature
Department of Health and Human Services
Centers for Disease Control and Prevention
What is Legionnaires’ Disease?
Legionnaires’ disease (LEE-juh-naires) is caused by a type of bacteria called Legionella. The bacteria got its name in 1976 when many people who went to a Philadelphia convention of the American Legion suffered from an outbreak of the disease, a type of pneumonia (lung infection). Although this type of bacteria was around before 1976, more illness from Legionnaires disease is being detected now. This is because we are now looking for this disease whenever a patient has pneumonia.
Where do Legionella bacteria come from?
The Legionella bacteria are found naturally in the environment, usually in water. The bacteria grow best in warm water like the kind found in hot tubs, cooling towers, hot water tanks, large plumbing systems or parts of the air-conditioning systems of large buildings. They do not seem to grow in car or window air-conditioners.
How do people get Legionnaires’ disease?
People get Legionnaires’ disease when they breathe in a mist or vapor (small droplet of water in the air) that has been contaminated with the bacteria. One example might be from breathing in the steam from a whirlpool spa that has not been properly cleaned and disinfected.
The bacteria are NOT spread from one person to another person.
Outbreaks are when two or more people become ill in the same place at about the same time, such as patients in hospitals. Hospital buildings have complex water systems, and many people in hospitals already have illnesses that increase their risk for Legionella infection.Other outbreaks have been linked to aerosol sources in the community, or with cruise ships and hotels, with the most likely source being whirlpool spas, cooling towers (air-conditioning units from large buildings), and water used for drinking and bathing.
United States Department of Labor
Occupational Safety & Health Administration
Section II:
What water systems in workplaces are potential sources of Legionnaires’ disease bacteria (LDB)?
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The primary sources of exposure to contaminated water in commercial and industrial facilities are water-cooled, heat transfer systems such as cooling towers or fluid coolers, and warm water sources such as domestic hot-water systems.
Operating Systems: Use the following modules to review maintenance, sampling protocol, treatment, and design considerations of each operating system.
Section II:A
Cooling Towers, Evaporative Condensers, and Fluid Coolers
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Cooling towers, evaporative condensers, and fluid coolers use a fan to move air through a recirculated water system. This allows a considerable amount of water vapor and sometimes droplets to be introduced into the surroundings, despite the presence of drift eliminators designed to limit droplet release. This water may be in the ideal temperature range for Legionnaires’ disease bacteria (LDB) growth, 20°-50°C (68°-122°F). Good maintenance is necessary, both to control LDB growth and for effective operation.