Although anyone exposed to the bacteria may become ill, there are certain risk factors that make some more likely to contract Legionnaires' than others. The disease occurs more frequently in women than men. It strikes the middle aged and elderly much more often than young people and it is quite rare in those under twenty. Smokers and those with underlying respiratory conditions such as emphysema are at greater risk, as are those with a compromised immune system. Legionnaires' Disease is an environmentally acquired disease. It cannot be transmitted person to person.
To manage the potential risks associated with Legionella, the first step is a risk assessment. This assessment should identify and evaluate the potential sources of Legionella contamination. It should also determine a method by which exposure to the bacteria can be prevented whenever possible. In the event that prevention is not possible, a method for controlling exposure should be recommended. One of the most common risk factors is water anywhere between 68 and 122 degrees Fahrenheit. The risk is greater when this water contains nutrients to support optimum bacteria growth. In water systems this may include slime, scale, rust, or even other bacteria. Another risk factor considers the potential for aerosol creation. Legionella spreads most effectively in very small, light droplets of water. The last major potential risk factor is the likelihood of stagnation. Stagnant water is the perfect breeding ground for bacteria and since it is either still or very slow moving, it is also often warm, thus increasing the potential bacterial load.
Risk assessments should be completed at least every two years or when there are substantial changes to the water system or use of the building or when new information regarding risk or control measures becomes available. Once the risks have been identified, steps can be taken toward prevention. The optimum growth temperature for Legionella is between 95 and 115 degrees but at 131 degrees the bacteria die within six hours and at 151 degrees they die within two minutes. Disinfection occurs at 160 degrees but a high temperature flush is a quick solution, not a permanent cure.
Legionella can also be inactivated by ultra violet light, however when the bacteria are in areas sheltered by corrosion, or are living in amoeba, UV is not always completely effective. Today the two most commonly used methods of preventing Legionella are ionization and chlorine dioxide. Copper-silver ionization is one of the most effective preventive measures against Legionella and is used by hundred of hospitals nationwide. Studies indicate that ionization is superior to both high heat and UV forms of eradication. Equally effective is chlorine dioxide; a highly effective disinfectant for use in combating Legionella. Chlorine has the added advantage of also eliminating the biofilm that often harbors and protects Legionella.
Legionnaires' Disease is a serious and potentially fatal disease. However, by assessing risk factors and taking appropriate preventive measures, it is possible to greatly reduce the factors that allow this detrimental bacteria to proliferate. The likelihood of Legionella infection can be greatly reduced by a combination of improved design and proper maintenance and disinfection of air and water handling systems.
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Your local health authoity or government environment agency will be able to provide more local qualification on legionella risk assessment requirements in you region. Resourced http://www.aquacert.co.uk
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