Legionnaires’ Disease Linked to Limescale Buildup
Legionnaires’ disease is making the headlines again, with at least 15 confirmed cases in April in Auckland, New Zealand. The cases are spread throughout the Auckland area, making it difficult to find the source and supporting the idea it’s likely present in more than one source. One person in Auckland has died after contracting the disease.
Officials in the Auckland region have encouraged over 300 building owners to chemically treat or “shock-dose” their cooling towers with a biocide to kill the outbreak.
Legionnaires’ disease is a type of lung infection caused by a bacteria called legionella, according to the Centers for Disease Control and Prevention (CDC). Legionella bacteria thrive in wet conditions, but they must be inhaled or aspirated to cause an infection. The elderly or those with compromised immune systems are more at risk for contracting Legionnaires’ disease. Early symptoms, which begin two to 10 days after exposure, include headaches, fatigue, muscle aches and abdominal pain. Complications from the disease may include respiratory issues and kidney failure.
The CDC estimates between 8,000 and 18,000 cases of Legionnaires’ disease occur in the US every year, with more than 10% of the cases becoming fatal. The vast majority of cases of legionellosis are the result of exposure to legionella through a water system. The Building and Engineering Services Association claims the figure is potentially higher than the number purported by the CDC as the symptoms are often similar to the flu.
Any place moisture can build up may cause bacteria, such as legionella, to grow. The bacteria can grow in hot tubs, air conditioning systems (especially large commercial units), hot water tanks, plumbing systems and cooling towers. Limescale deposits in the water system allow water to pool when the fixtures aren’t in use. This pooling allows bacteria to grow and potentially infect those using or exposed to the system.
“By far the greatest risk lies within the humble hot and cold water systems, which deliver the disease through taps and shower heads. Legionella bacteria thrive in temperatures between 20-45 degrees Celsius; and if water is allowed to sit at these temperatures the bacterium can multiply into large numbers which can cause Legionnaires’ disease,” according to Simon French, a legionella expert and HVCA Service and Facilities Group member.
People involved in building management must understand the health risks associated with poorly maintained water systems. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) publishes standard practices aimed at reducing the risk of legionellosis.
ASHRAE identifies the conditions in a building’s water system that make it less likely for legionella to grow and spread and recommends maintenance procedures and hazard controls to stop the spread of the bacteria. The standards are aimed at building/facility owners and managers, but they’re also useful to people involved in designing water systems to ensure their practices are adequate to prevent legionella exposure.
- Read our blog post “How to Prevent Legionnaires Disease via Cooling Tower Cleaning.”
- Check out our learning center on how best to maintain your facility’s existing cooling tower.
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- Stay up to date on facility maintenance tools such as chiller tube cleaners, boiler tube cleaners, hose/pipe cleaners, descaler systems, industrial vacuums, commercial pressure washers, and drain cleaners.
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