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Legionnaires’ outbreaks serve as reminder to manage risk

Start with proper environmental assessment to control bacteria growth

By Glyn Jones

Safety practitioners need to maintain a level of comfortable unease when it comes to managing everyday risks at work. This includes the risks associated with working in large buildings, such as a lung condition called legionnaires’ disease. Last December, a Quebec judge awarded $7.5 million to be shared by more than 200 victims of a 2012 legionella outbreak — the bacteria that causes legionnaires’ disease. In that outbreak, 14 people died. Last September, health officials had to respond to an outbreak in Surrey, B.C. that affected seven individuals. The risks are real and there is a clear and present danger of legionnaires’ disease wherever people work in big buildings. Symptoms of legionnaires’ disease include fever, chills, coughs, muscle aches, diarrhea, headaches and shortness of breath. According to the CDC in the United States, one out of every 10 people who gets sick with the disease will die.

Legionella is a type of bacteria found naturally in freshwater environments, such as lakes and streams, and it includes more than 50 species. In nature, it is usually present at very low concentrations. The species most commonly connected to health impacts is legionella pneumophila. Legionella becomes a health concern when it grows, concentrates and spreads in the plumbing systems or when it is allowed to become aerosolized and distributed in the ventilation systems of modern buildings. Legionella can accumulate in any large-scale plumbing systems, including decorative fountains, showerheads and sink faucets, hot water tanks and heaters. It is commonly found in cooling towers that are part of any building’s centralized air conditioning system. It can be a significant risk when it accumulates in the spray cooling and humidification system of a building’s centralized ventilation.

When legionella is allowed to grow and concentrate in a building’s water system, the contaminated water containing the bacteria can be aerosolized and spread as tiny droplets small enough to be carried in the ventilation system and inhaled by humans. If the exposure is high enough, people can get sick when they breathe in small droplets of legionella-contaminated water in the air. A less common but possible route of exposure is aspirating drinking water contaminated with the bacteria. This happens when water accidentally goes into the lungs while drinking, typically at a water fountain.

Legionnaires’ disease is not the only illness than can arise from exposure to the legionella bacteria. Individuals can also contract Pontiac fever, named after an outbreak in 1968 in Pontiac, Mich., which resembles influenza. Legionnaires’ disease requires treatment with antibiotics and is quite serious. Pontiac fever typically goes away without specific treatment. The CDC reports that the incidence of legionnaires’ disease and Pontiac fever is five times more common today than it was in 2000.

It is likely that at some point in your life you have already been exposed to legionella. Most healthy people exposed to the bacteria at lower concentrations do not get sick because their immune systems provide the necessary protection and defence. People at the greatest risk of getting sick are those with compromised or suppressed immune systems, such as the elderly, people with chronic lung disease and chemotherapy patients.

Legionnaires’ disease can be prevented by ensuring that building water systems are properly maintained in order to reduce the risk of legionella growth and concentration. Any significant vibration or fluctuation in the pressure of the water system may allow legionella to flow into it. The bacteria grows best at temperatures above room temperature (25 C to 40 C), but it has been known to grow outside of this range. The most common water treatment to prevent legionella growth and concentration includes chlorination and ensuring residual chlorine is maintained in the standing water of all systems.

A starting place for controlling the risk of legionella growth is a proper environmental assessment, which requires you to have a good understanding of building systems that use or distribute water. This will be helpful in determining where legionella may grow. Consider, too, the municipal water quality and factors that may influence it, such as construction in the area and water main maintenance. The assessment will involve a visual inspection and monitoring of water quality parameters such as temperature, pH and residual disinfectant, in addition to the presence of the legionella bacterium. Any samples collected need to be sent to a laboratory accredited to a recognized federal or international standard for legionella culture testing. A long-term control strategy will typically involve establishing a risk management plan, referred to as a water management plan. It will include a program of proactive and regular testing.

As a safety practitioner, you need to master risk management and start looking for — and managing — risks that you may not even be able to see, such as legionnaires’ disease. We need to tune in and take action. The trend of employees becoming ill and dying from legionella needs to stop.

Glyn Jones

Glyn Jones is a partner at EHS Partnerships in Calgary. He is a consulting occupational health and safety professional with 30 years of experience. He also provides program design and instructional support to the University of New Brunswick’s OHS certificate and diploma programs. You can follow him on You can follow him on Twitter at @glynjones_ehsp or he can be reached at gjones@ehsp.ca.
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