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CDC Legionella toolkit

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DEVELOPING A LEGIONELLA WATER MANAGEMENT PROGRAM 3 Glossary Biofilm (slime): Germs and the slime they secrete that stick to and grow on any continually moist surface; provides housing, food, and security for many different types of germs, including Legionella Building water systems: Includes hot and cold water distribution and all devices that use water people can be exposed to, such as hot tubs, decorative fountains, and cooling towers Control: To manage the conditions within your building according to your water management program Control measures: Things you do in your building water systems to limit growth and spread of Legionella, such as heating, adding disinfectant, or cleaning Control limits: The maximum value, minimum value, or range of values that are acceptable for the control measures that you are monitoring to reduce the risk for Legionella growth and spread Control points: Locations in the water systems where a control measure can be applied Contingency response: Reaction to control measures that are persistently outside of control limits or events that pose an immediate risk to control of your building water systems; required for all instances when Legionnaires' disease occurs, but may also be appropriate for unexpected events such as equipment failure or acts of nature that disrupt the water system Corrective action: Steps taken to return control measures to acceptable levels Dead legs: Piping that is subject to low or no flow due to design or decreased water use such as capped pipes or unused faucets Disinfectant: Chemical or physical treatment used to kill germs, such as chlorine, monochloramine, chlorine dioxide, copper-silver ionization, ultraviolet light, or ozone Hazardous conditions: Anything that, if not controlled, can contribute to the growth and spread of Legionella to a person Healthcare facility: A place where patients stay overnight for medical care or where people with chronic or acute medical problems* are treated; this may include inpatient or outpatient care areas Heterotrophic plate counts: A measure of the number and variety of bacteria that are common in water; a high count may indicate a high microbial load and the need for corrective action, but cannot be substituted for Legionella testing Legionella: Bacteria that can cause Legionnaires' disease Legionnaires' disease: A serious type of pneumonia caused by Legionella Residual: The amount of disinfectant available in water to kill germs Scale and sediment: The mineral build-up in a water system that uses up disinfectant and supports germ growth and/or survival Stagnation: When water does not flow well; areas of stagnant water encourage biofilm growth and reduce temperature and level of disinfectant * Burns, cancer, solid organ or bone marrow transplant, kidney disease, diabetes, or chronic lung disease Reference: ASHRAE 188: Legionellosis: Risk Management for Building Water Systems June 26, 2015. ASHRAE: Atlanta. www.ashrae.org

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