Engineered Systems - February 2008 - (Page 46) Humidification, air intake location, and cooling tower operation — these three components continue to require vigilance in preventing Legionella from cropping up. Smart choices, from design through ongoing maintenance, can prevent problems and protect health. BY MATTHEW FREIJE L egionnaires’ disease is costly. Building owners, or their insurers, pay big legal bills defending lawsuits brought by people who claim to have become ill from exposure to a water system that harbored Legionella bacteria, or by the families of those who die from the disease. Some businesses pay even more in lost business due to bad press and word of mouth. But the highest price is paid by the people who get sick, some suffering long term or even dying from the disease. More than 95% of the Legionnaires’ cases that are contracted at hotels or other public places (not including hospitals) go undetected, and only a sliver of the 5% that are detected are reported by the press. Public perception, therefore, is that the disease is rare, when in fact 8,000 to 18,000 cases occur each year in the United States, according to the Centers for Disease Control and Prevention (CDC) in Atlanta. As public awareness increases and diagnostic technology improves, a much higher percentage of cases will likely be diagnosed and reported. Legionnaires’ disease is contracted by exposure to water contaminated with Legionella bacteria. People can be exposed to Legionella while using a bathroom faucet, showering, bathing in a whirlpool spa, walking by a water feature, or drinking from a water fountain. Also, Legionella-contaminated water mist can drift from cooling towers to building occupants through fresh air intakes or windows, or directly to individuals who are outdoors. The bacteria can be inhaled into the lungs in small airborne water droplets, or aspirated (choked) into the lungs while drinking. To reduce health and legal risk, facility manag- ers should take steps to minimize Legionella bacteria in plumbing systems, whirlpool spas, water features, cooling towers, and other water systems. About 20 countries have guidelines for reducing the risk of Legionnaires’ disease. In Australia and the United Kingdom, violations that result in disease can carry stiff penalties and even prison terms. Although guidelines in the U.S. are generally not as thorough and are not mandated, several U.S. government agencies and industry groups advocate a proactive approach to minimize Legionella bacteria in water systems, including the EPA, the Occupational Safety and Health Administration (OSHA), ASTM International, and ASHRAE. The guidelines do not agree on every detail, but virtually all of them recommend preventive measures to minimize Legionella bacteria in water systems. The prevention program should start with an expert assessment of plumbing systems, cooling towers, and other water systems to identify conditions that promote growth or transmission of Legionella bacteria. The next step is to write a waterborne pathogens management plan that outlines specific risk reduction measures (based on the assessment findings) and policies and procedures for maintenance and operation of water systems. Education is especially important, so that employees and contractors routinely involved with the water systems know how to identify and correct conditions conducive to contamination. Routine water testing for Legionella should be done to check the effectiveness of the preventive program, and appropriate remediation implemented based on the test results. 46 En gi neer ed S y stem s February 2008
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