Shaping the future of Legionella control
Legionnaires’ disease (also known as Legionellosis) is a potentially fatal form of pneumonia caused by Legionella bacteria. This bacteria can infect people when they inhale tiny aerosolized water droplets or particles that contain elevated levels of Legionella bacteria.
Legionella bacteria thrive in temperatures between 20°C – 45°C, with an optimal range of 35°C – 40°C. To control the bacteria, it’s essential to keep hot water temperatures at a minimum of 60°C, as this high temperature can kill Legionella effectively.
Legionella bacteria are found in low numbers in natural aquatic environments, for instance, lakes, rivers and ground water. As a result, it is virtually impossible to prevent Legionella bacteria entering man-made water systems.
In low numbers the bacteria are generally considered harmless. With the correct conditions, for example, warm water, the presence of micro-organisms and nutrients in the water or materials such as rust, these bacteria can grow and multiply to high levels which increase the risk of exposure.
The bacteria tend to grow in biofilms (slime). Biofilms are likely to form on surfaces where there is low water flow or water is allowed to stagnate. However the growth of Legionella bacteria can be controlled.
If you’re a building or facilities manager, or a Responsible Person, you have critical Legionella control responsibilities to safeguard against Legionnaires disease. Specifically, you must:
As a certified member of the Legionella Control Association, HBE provides Legionella control services across the UK and Ireland. Our services support compliance with legislation and help facility managers meet their responsibilities regarding Legionella testing and control. We provide the following services to help the building manager to discharge their duties and obligations relating to the control of legionella bacteria in water systems:
We adhere to and utilise the following legionella guidance / documents, when devising legionella control programmes:
Legionella is not a sector-specific risk. However, the HSE consider key sectors being manufacturing, health and social care, and leisure and, within these, there is a range of systems and premises which give rise to varying levels of risk. These include Cooling towers, air conditioners, spa equipment, fountains, humidifiers and showers, hot and cold water systems, oil/water emulsions used for lubricating lathes, misting devices, decorative fountains and water features, dentistry tools and TMVs (thermostatic mixing valves).
The HSE have used the following criteria, to determine risk groupings:
The risk grouping is based upon an analysis of both the risks posed and the likely impact that would arise from an outbreak.
The HSE’s groupings are as follows:
These systems operate at optimum temperatures for the growth of bacteria. They are re-circulating systems that can allow bacteria to build up within the system and generate large quantities of aerosol that, if uncontrolled and dispersed, can spread into the general environment, potentially affecting the general public.
Such systems are generally associated with a larger number of exposures during individual outbreaks, and can be described as low frequency/high impact occurrences.
These ubiquitous systems operate at optimum temperatures for the growth of legionella bacteria and they may be connected to outlets and showers that can generate an aerosol when in use. In some premises, the water system can be extremely complex e.g. hospitals, but the majority of premises have much simpler systems (such as in care homes, hotels etc).
Hot and cold water systems are associated with low numbers being exposed and little or no off-site impact. However, outbreaks in hospitals are characterised by an increased likelihood of major ill health effects or death following infection because the exposed population is more vulnerable.
These systems generally operate at optimum temperatures for growth of bacteria, including legionella. They are re-circulating systems that, when not properly controlled, allow bacteria to build up within the system and the mode of operation generates an aerosol in the vicinity of the breathing zone of the user/s.
The HSL review of outbreak data indicates that, in GB, the ill health outcomes from exposures in spa pools are sometimes less serious, e.g. Pontiac fever. However, they are associated with large numbers of exposures during individual outbreaks.
These systems include fire sprinkler units, pressure washers, spray humidifiers, fogging and water misting systems, emergency showers, train/car and bus washers, outdoor and indoor fountains and water features, composting facilities and irrigation systems.
In fact, any industry that uses water for processes such as washing, misting and cooling may pose a legionella risk as such systems commonly allow water to stagnate and generate aerosols that can potentially be spread into the environment. They are variable in nature and scale and are less likely to affect large numbers of people.
Legionella control refers to measures taken to prevent the growth and spread of Legionella bacteria in water systems, reducing the risk of Legionnaires’ disease. This includes regular risk assessments, temperature monitoring, and system disinfection.
It is critical for health and safety compliance, preventing outbreaks of Legionnaires’ disease, and ensuring the safety of water systems in facilities such as healthcare, education, and public buildings.
Legionella control is guided by legislation like ACoP L8, HSG274, HPSC National Guidelines for the Control of Legionellosis in Ireland 2009, and health and safety regulations, including BS 8580 for risk assessments and HTM 04-01 for healthcare settings.
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