The Basics About Legionnaires' Disease And HVAC Systems

HVAC systems have long been known to be a major culprit in the spread of Legionnaires’ disease. Anyone working in the HVAC industry should be familiar with this very important topic, and learn what they can do to help prevent this very serious disease.

Legionnaires’ disease, or Legionellosis, is caused by the bacterium Legionella pneumophelia. This bacterium is a particular type of pneumonia that can result in people developing coughs, aches, chills, fever, in addition to a variety of other serious symptoms. The L. pneumophelia bacterium has been traced back to the 1960’s; however, in 1976, when 221 attendees at an American Legion convention in Philadelphia became ill, resulting in the death of 34 people, scientists began researching the cause of the disease. Finally, in 1976, the bacterium was identified and named.

Legionnaires’ disease is most commonly found in air conditioning systems and cooling towers, but can also be present in shower heads, hot tubs and other elements. Warm stagnant water in HVAC systems can provide the ideal environment for the bacterium to grow. When central HVAC systems are used, the bacterium is then dispersed into the air. Of course, with the bacterium airborne, people are exposed to it simply by being in the building and breathing the contaminated air.

While Legionnaires’ disease is often effectively treated with antibiotics, up to 30% of the people who contract this disease will die from it. The CDC reports that approximately 18,000 U.S. citizens are hospitalized each year with Legionnaires’ disease. Clearly, the best course of action is to prevent the disease rather than react to the disease once people become sick.

There have been numerous outbreaks of Legionnaire’s disease since 1976 and many of these cases have been traced to an HVAC system. Europe has implemented what they call, “Approved Code of Practice and Guidance L8” as a means of trying to effectively prevent Legionnaire’s disease. It is clear that prevention requires managing all phases of the HVAC system. From initial design and installation to proper operation and routine maintenance, focusing on HVAC systems can help prevent Legionnaire’s disease.

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