Potential Hazard Employee exposure to Legionnaires' Disease. Legionnaires' Disease is a bacterial disease commonly associated with water-based aerosols and often a result of poorly maintained air conditioning cooling towers and potable water systems. It can occur where water, contaminated with the legionella organism, is aerosolized and then breathed in by workers or patients. Legionnaires' Disease is not contagious but is of environmental origin. Consequently, only those who are directly exposed to the contaminated aerosolized water source can get the disease.

Hydro-therapy Whirlpool Tub

• Exposure to the legionella bacteria could occur in the shower or whirlpool area, or areas that use spray nozzles. Cooling towers, evaporative condensers, fluid coolers, and domestic hot-water systems are water sources that frequently provide optimal conditions for growth of the legionella organism. 

• Exposure to the legionella bacteria can cause a mild respiratory illness (that may not require treatment), or severe pneumonia-like symptoms 2 to 10 days after exposure.
  
  • If not detected and treated promptly with appropriate antibiotics, can lead to death.
    
    
  • Fatality rate is approximately 15%.

Good work practices found in the OSHA Technical Manual on Legionnaires' Disease include:

Maintenance of water systems at specified recommendations:

• Domestic hot-water systems:
  
  
  • Store water at 140 degrees F and deliver it at a minimum of 50°C (122°F) to all outlets. To avoid scalding problems install fail-safe scald protection equipment, such as preset thermostatic mixing valves.
    
    
  • Where building cannot be retrofitted, consider periodically increasing the temperature to at least 158 degrees F or chlorination followed by flushing should be considered.
    
    
  • Inspect systems annually to ensure equipment is functions properly.
  
  
• Domestic cold-water systems:
  
  
  • Maintain cold-water lines below 68 degrees F.
    
    
  • Eliminate water tanks that allow water to remain uncirculated for long periods or design them to reduce storage time to a day or less. They should also be covered and protected from temperature extremes.
    
    
  • Prevent cross-contamination of the domestic cold water system with other systems.
    
    
  • Use hyperchlorination to eradicate legionella if the cold-water lines have significant contamination.
  
  
• Clean and disinfect Cooling towers at least twice a year.
  
  
  • Use biocides periodically to control bacteria growth.
    
    
  • Provide visual inspection and periodic maintenance of the system, to prevent buildup of scale and sediment and bio-fouling, which support legionella growth.

Legionnaires' Disease Chapter 7 Section III, OSHA Technical Chapter, also provides: Controls, Source Identification.

• Appendix III:7-5. OSHA Technical Chapter, Water Treatment Protocols for Facilities that have experienced a Legionnaires' Outbreak.
  
  
• Appendix III:7-1. Employee Awareness Program, to inform employees of any potential outbreaks, and to educate about the disease, and provide early recognition of the disease. Sample forms and questions and answers about Legionnaires' disease are provided.

The CDC in Legionellosis: Legionnaires' Disease and Pontiac Fever recommends these methods to limit the growth and spread of legionella organisms:

• Improving design and maintenance of cooling towers and plumbing systems.
  
  
• Identifying the source of disease transmission and providing appropriate prevention and control measures, such as the decontamination of the water source.
  
  
• Flushing tubing or piping used in dental/clinical settings with air periodically (at the end of the shift or while not in use).

Medical Awareness of Physicians and Health Care Workers (HCWs):

HCWs need to be aware that the bacteria can be present in water systems and promptly test vulnerable and/or symptomatic patients and use appropriate antibiotics quickly.

• Legionnaires' Disease most frequently attacks individuals who have an underlying illness or weakened immune system. The most susceptible include persons who are elderly, smokers, and immunosuppressed.
  
  
• Symptoms include: dry cough, high fever, chills, muscle aches, diarrhea, fatigue, headache, and abdominal pain.
  
  
• Usually treated with erythromycin or a combination of erythromycin and Rifampin.

• Legionnaires' Disease eTool. This eTool was designed to assist industrial hygienists in the assessment of worksites for potential Legionnaires' disease. It provides information on disease recognition, investigation procedures to identify probable water sources, and control strategies.
  
  
• In September of 1999, the Joint Commission on Accreditation of Healthcare Organizations, (JCAHO) Committee on Healthcare Safety updated the current Environment of Care Standards to address issues of improperly designed and maintained aerosolizing water systems (controlling pathogenic biological agents such as legionella in cooling towers, domestic hot water systems, etc).