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August 15, 2024

Mitigating Risk of Legionella on Your Properties

By Brian E. Nemetz, CMC

By Brian Nemetz, CMC, National Technical Director of Industrial Hygiene for Partner ESI

What is Legionella and why should property owners care?

Legionella was first detected after a 1976 outbreak at the Philadelphia American Legion Convention.  This first outbreak was responsible for 240 confirmed cases and a total of 34 deaths, although at the time, no one was aware of the disease or the water-borne bacteria that caused the outbreak. Since this tragic event, a tremendous amount of research has been dedicated to the identification and control of Legionella bacteria. The Centers for Disease Control and Prevention (CDC) estimates that about 8,000 to 18,000 Americans develop Legionellosis each year.    Unfortunately, most cases go undetected as they are misdiagnosed as pneumonia.

What is Legionnaire’s Disease?

Legionnaire’s Disease, or Legionellosis, is caused by more than forty species of Legionella bacteria, with Legionella pneumophila being the most common species to infect humans. Legionnaire’s Disease is generally contracted through inhalation of airborne water droplets that contain the bacteria. The water containing the bacteria is misted by a shower, cooling tower, HVAC system, etc., and inhaled by people within the vicinity of the source.

Legionella bacteria can survive in water that ranges from 68oF to 122oF and grow in temperatures ranging from 77oF to 108oF, which means that cooling towers, as well as domestic and commercial hot-water systems, are within the prime range to support the growth of Legionella bacteria. And while hot temperatures are ideal for bacteria preservation and growth, there have been samples collected from cold-water systems, including the domestic cold-water intake, that have confirmed the presence of Legionella bacteria.

Both government and private institutions have worked to develop guidelines to control the development and management of the bacteria, but it has not been enough to stop the spread of Legionnaire’s disease. The CDC offers numerous guidance documents to aid in the control and sampling of Legionella, while the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) released a standard (188-2021) titled Legionellosis: Risk Management for Building Water Systems. Both publications are utilized across the country regardless of the legal necessity to comply in the interest of public safety.

Proactive Approach to Managing Risks on Your Properties

Facilities that house a population susceptible to Legionellosis, such as healthcare facilities, nursing homes, jails, office buildings, and Housing Authorities, should perform some proactive investigation of their facilities as a means of identifying potential problems prior to any identified case of Legionellosis.

If the facility is at risk, there are a number of professional assessments and practices that will aid in the early detection and control of Legionella bacteria:

  • Targeted facility site inspections to evaluate potential systems that may contribute to Legionella
  • Inspection of all water systems.
  • Development of a best practices plan to prevent and/or eliminate the future growth of Legionella
  • Heterotrophic plate counts, pH level Chlorine residual and/or Legionella
  • Implementation of water-treatment systems to reduce Legionella bacteria within the water system.

Best Practices for Assessing and Treating Legionella on Properties

With that knowledge in hand, Partner strongly recommends the investigation of the entire water system including by not limited to the showers, domestic water intake, faucets, etc. We know that Legionellosis is contracted by inhaling water droplets with the bacteria in it.  As such, it is likely that showers cause a considerable number of cases.

There are numerous ways to disinfect a water system. Temporary solutions include “super chlorination” and “super heating.”  Some property owners have decided to install permanent systems that inject chlorine, chlorine dioxide, and/or copper and silver ions. Each method/system has its strengths and weaknesses, so a qualified environmental consultant and/or engineer should be involved in the decision process.

Most importantly, make sure to engage a consultant with direct expertise and experience in the identification of Legionella sources and in the design of management plans and systems to control and eliminate the potential growth of Legionella bacteria. Working closely with the DOH will help your consultant to quickly identify the potential source of the concern and develop effective strategies to address it.

Reach out to your Partner Rep or contact Brain Nemetz, CMC directly with any questions or concerns you have about Legionella risk or control programs.

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