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What is a cooling tower and how can it spread Legionnaires’ disease?

By in Press Enterprise on November 17, 2017

By Kurt Snibbe, Kevin Sablan

Orange County health officials are investigating cooling towers near the Disneyland resort area after 15 cases of Legionnaires’ disease were reported by people who live in or visited the Anaheim area in September. County Health Officer Dr. Eric Handler ordered Disneyland on Nov. 8 to stop using two of its cooling towers.

Cooling towers are at the center of the investigation because they are known to be breeding grounds for the bacteria that causes Legionnaires’ disease, a lung infection caused by the Legionella bacteria.

What is a cooling tower?

A cooling tower is a device that takes hot water out of a system (like an air-conditioning unit), cools it, and then recycles that cooled-off water back into the system.

This is how a cooling tower typically works:

  • Warm water from a heat source such as commercial air conditioning is piped into the top of the cooling tower.
  • The water is sprayed down to cool and evaporate.
  • Large fans increase evaporation and help cool the water, creating mist.
  • The fans emit the mist out the top of the cooling tower and into the atmosphere.
  • Mist from cooling towers can get you sick

    According to the Occupational Safety and Health Administration, inhaling water mist that contains Legionella bacteria is the only way a person can develop Legionnaires’ disease. The disease is not contagious. It can’t be transmitted from person to person.

    In a chapter of a technical manual dedicated to Legionnaires’ disease, OSHA explains that cooling towers and water heaters provide ideal conditions to grow the Legionella bacteria. The temperature of the water can fall within the ideal range to grow Legionella: 68-122 degrees Fahrenheit. As the cooling tower moves air through a recirculated water system, it releases a “considerable amount of water vapor” into the atmosphere. If it contains Legionella bacteria, people can get sick by inhaling that vapor.

    Legionella […]    

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