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.
Possible Solutions
Good work practices found in the OSHA Technical Manual
on Legionnaires' Disease (Chapter 7
-
Section III) include:
Maintenance of water systems
- specific 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.
- Inspect systems annually to ensure equipment 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.
OSHA Technical Chapter, also provides Controls,
and
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.
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.
Additional Information:
-
Legionnaires'
Disease. OSHA 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.
-
Environmental Care: Utility System and Acquired Illness. Joint
Commission, Environment of
Care Standards, (2008, November 24). 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).
-
Patient Facts: Learn More about Legionnaires' disease. Centers for
Disease Control (CDC), (2008, June 27).
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