A new Center for Disease Control and Prevention (CDC) study involving 196 cooling towers nationwide found that 84 percent contained Legionella DNA, indicating that the dangerous bacteria that causes a severe, even fatal type of pneumonia were present or had been at some point. This means the real question is not ‘if there will be another outbreak’ but only ‘where and when’ it will occur.
“During 2000–2014, passive surveillance for legionellosis in the United States demonstrated a 286 percent increase in reported cases per 100,000 population,” states the CDC website. The CDC also estimates that about 5,000 cases of Legionnaires’ disease are now reported each year in the United States, and keeping Legionella out of water systems in buildings, with cooling towers a noted risk, is critical in preventing infection.
In response, HVAC contractors now are pairing chillers and high performance plastic cooling towers with new anti-microbial options that significantly reduce the infection risk. Throughout the U.S. and most of the world, the mainstay of large cooling systems remains the traditional HVAC combination of chillers, air handlers and cooling towers. Cooling towers have a long history of effective use in expelling heat from the water used in many commercial and industrial applications that involve chillers.
However, it is well established that, under typical operating conditions, cooling towers can propagate Legionella. The design of many cooling towers creates pockets where water may stagnate, a condition that can lead to microorganism development.
Original URL: https://www.facilitiesnet.com/iaq/contributed.aspx?id=40126
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