Issue link: https://hi.iaq.net/i/692160
DEVELOPING A LEGIONELLA WATER MANAGEMENT PROGRAM 13 4 Decide Where Control Measures Should Be Applied Control measures and limits should be established for each control point. See the diagram on the next page for the types of monitoring that could occur in Building A. You will need to monitor to ensure your control measures are performing as designed. Control limits, in which a chemical or physical parameter must be maintained, should include a minimum and a maximum value. Examples of chemical and physical control measures and limits to reduce the risk of Legionella growth: 6 6 6 6 Water quality should be measured throughout the system to ensure that changes that may lead to Legionella growth (such as a drop in chlorine levels) are not occurring. Water heaters should be maintained at appropriate temperatures. Decorative fountains should be kept free of debris and visible biofilm. Disinfectant and other chemical levels in cooling towers and hot tubs should be continuously maintained and regularly monitored. Surfaces with any visible biofilm (i.e., slime) should be cleaned. Healthcare Facilities Clinicians should test patients with healthcare-associated pneumonia for Legionnaires' disease. This is especially important among patients at increased risk for developing Legionnaires' disease (see Appendix A), among patients with severe pneumonia (in particular those requiring intensive care), or if any of the following are identified in your facility: • • • Patients with Legionnaires' disease, no matter where they acquired the infection Positive environmental tests for Legionella Changes in water quality that may lead to Legionella growth (such as low chlorine levels) The preferred diagnostic tests for Legionnaires' disease are culture of lower respiratory secretions on selective media and the Legionella urinary antigen test. Additionally, certain commonly-encountered changes in building water system design or management might require increasing increasing the extent and frequency of monitoring. It's a good idea to anticipate additional hazardous conditions that could be associated with scheduled or unanticipated changes in water quality, such as: 6 6 6 6 6 6 System start up System shut down Regularly scheduled maintenance Renovations, construction, and installation of new equipment on your property Equipment failure Water main break or other service interruptions Anti-scald Regulation You should follow local and state anti-scald regulations. However, maximum temperatures allowed by your state may be too low to limit Legionella growth. Engineering controls that mix hot and cold water together at the source can reduce the risk of scalding while allowing water in pipes to remain hot enough to limit Legionella growth. Reference: ASHRAE 188: Legionellosis: Risk Management for Building Water Systems June 26, 2015. ASHRAE: Atlanta. www.ashrae.org