Legionella – a proactive approach to prevention
With a number of recent legionella cases hitting the headlines, SARAH BAILEY says facilities managers need to put a risk management system in place to safeguard workplace health.
Legionnaires’ disease is a serious respiratory infection, associated with water systems within buildings. Outbreaks have occurred worldwide, linked to cooling towers used for air- conditioning, and also the drinking water and other water systems inside buildings.
Although in public perception the disease is usually associated with air-conditioning, over half of the outbreaks have occurred in association with the internal water systems of a building. All buildings can potentially have the conditions present to allow colonisation of the water systems with legionella bacteria, and outbreaks have been documented from hotels, shopping centres, factories, commercial office towers, manufacturing plants, hospitals and schools.
Facilities managers should be aware of the risks associated with this disease, and take steps to have a risk management system in place to control these risks.
A wide range of different guidelines, codes of practice, standards and legislation exists around legionella control in Australia, with each state and territory having its own, very different requirements and guidelines.
A white paper review of each state and territory from 2016 can be found on the QED Environmental Services website if you require direction as to the requirements. Since the publication of this white paper, however, New South Wales and Queensland have updated their legislation, so the latest information should be sought from the relevant state or territory health department.
For cooling towers, along with referring to your state/territory’s specific requirements, a great source of information is the Victorian guidelines on the health.vic website, which has good explanations of risks and risk assessments for cooling towers. A specific guideline exists on the federal Department of Health website for water systems (excluding cooling tower systems) for health and aged care premises. This covers the whole of Australia and is an excellent source of information for all facility managers, not just those in healthcare.
Although state and territory requirements specific to legionella differ, the occupational health and safety acts of each state and territory do cover legionella risks in that the workplace must be a safe environment to work in, and that people in it and around it should not be impacted adversely by the workplace.
Assessing the risks in the property that you manage, and introducing strategies to reduce those risks, is vital in providing a safe and healthy environment for visitors, staff and occupants. Once an outbreak or case of legionella has been discovered, it is often very difficult to trace the source for some time – meaning that an outbreak can go on unchecked for an extended period, and more people can become infected.
The consequences of an outbreak can be serious – the disease itself can be very debilitating for those in vulnerable groups, and can result in death, hospital admission and intensive care admission. There can also be long-term effects on health. The Age newspaper reported in 2004 that, of the more than 140 people exposed in the Melbourne Aquarium outbreak, four people died and some of those surviving still had debilitating health problems many years later.
From a business point of view, the consequences can also be significant. These can include closure of a facility, and outbreaks can impact on the public perception of the company involved. There are also the costs involved with remediating a system that has become out of control, and compensation costs and fines, which can be several million dollars.
There are specialist companies that can carry out detailed risk assessments for legionella within your property and for cooling towers. There are, however, some simple steps that a facility manager can take to initially assess and deal with some of the more major risks. Specific legionella awareness training for facility managers is also an excellent idea – most outbreaks worldwide have found that lack of training for those operating the systems was a major factor in the outbreak occurring.
As previously mentioned, the Victorian guidelines are an excellent reference for assessing the risks of cooling towers. Some of the main points to bear in mind when looking at a system are:
- Stagnant water: How often is the system idle, and are there any dead legs where water does not circulate properly?
- Nutrients: Can environmental contamination enter the system; for example, construction dust and debris? Is there a corrosion control program in place and how much sunlight is the system exposed to?
- Poor water quality: Is the water treatment program effective and automated, and does it have biocide control?
- Deficiencies in the system: Does the system comply with Australian standards, and are drift eliminators fitted?
Location and access: Could the tower be located where there are fewer people exposed to the drift from the tower? Communication with water treatment and mechanical services contractors is also essential. With increasing pressure on contractors to decrease costs, and with KPIs including no detections of legionella, there may be pressure to collect samples that are not necessarily representative of the tower conditions.
Independent testing, carried out by a company that is not providing either mechanical or water treatment services, should be seriously considered to ensure safety. Review of all documentation and recommendations from the monthly service visits should be carried out by the facility manager, and any required action taken swiftly. It is easier to keep a tower under control than to bring an uncontrolled tower back under control.
This primarily refers to the potable water system used for drinking and showering, for example. Legionella risks exist in any water system, however, and there are many that may be overlooked when undertaking a risk assessment. These include, but are not limited to, steam mops/mops, water filters, humidifiers, decorative fountains, misting devices in outdoor areas and garden reticulation. Uses of water in each facility will be very different.
Two of the key issues to be considered with the interior water system are temperature and stagnation. Ideally, hot water should be above 60 degrees Celsius in the hot water loop. This will aid in adequately controlling legionella in the water inside the system. Any areas where the water temperature falls below this can become colonised with legionella. Additionally, in Australia the temperature of the incoming cold water supply can often be above 20 degrees Celsius and so be at risk of legionella colonisation. Lack of insulation on pipework, and hot water pipes running next to cold water pipes, may also raise the temperature of water in the building to at risk levels.
A major risk for colonisation of a system with legionella is stagnation of the water. Plumbing dead legs (a piece of pipe where water cannot circulate) can accumulate sediment and be an ideal environment for legionella proliferation. The chlorine levels in the incoming water also decrease in these areas, leaving them more at risk. Outlets that are not used have the same issue; for example, unused showers, car park taps and bathrooms that have been turned into store cupboards. Identifying these outlets and setting up a program of regular flushing will help control risks.
As with cooling towers, a program of regular testing to supplement the risk assessment should be undertaken.
With adequate knowledge and training for facility managers, and a thorough risk assessment of the cooling towers, associated systems and the plumbing system of a building, the microbiological risk can be controlled to drastically reduce the chances of a problem with legionella within the building. ●
Sarah Bailey is a senior consultant at QED Environmental Services.
This article also appears in the April/May issue of Facility Management magazine.
Lead image: 123RF’s Leung Cho Pan © 123RF.com