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Legionnaires'
Disease |
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Wherever there is water, there exists the ever-present
risk of legionella breeding and legionnaires' disease.
Guidance on preventing and controlling legionellosis,
including legionnaires' disease, was published in January 2001
by The Health & Safety Executive. This code of practice will provide
useful guidance for those responsible for these issues.
Symptoms
Legionnaires' disease is characterised by pneumonia
and is caused by the bacterium legionella pneumophila. Symptoms
can appear quite suddenly and include high fever, chills, headache,
muscle pain and a dry cough. Difficulty with breathing is also
commonly experienced. The illness can be fatal.
According to the national surveillance scheme for
legionnaires' disease, there were 226 reported cases in England
and Wales in 1998, of which 25 resulted in death. Infection can
be by the inhalation of airborne water droplets or particles containing
Legionella and which are small enough to pass deep into the lungs.
Origins
The name Legionnaires' Disease (LD) comes from an
outbreak among people who had attended an American Legion Convention
in Philadelphia. Since then, each outbreak has received high publicity,
and legislative and guidance documents have been published in
the UK detailing required procedures to eliminate or minimise
the risk of future outbreaks.
There is concern that the risk of Legionella is
not getting the attention it deserves. Whilst LD is uncommon,
Legionella organisms are widespread and can be found in both natural
and man-made water systems, as well as soil. There are numerous
species of legionella. In circumstances that promote the proliferation
and distribution of the bacteria, everyone is at risk. The old
and children are most susceptible.
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You can minimise the risk of
legionnaires' disease using this 3-part plan:
- Undertake a risk assessment, including a review
of the following:
- the systems in place
- the installation and whether there are items
which could be improved to reduce risk
- the maintenance procedures in place. Are they
appropriate?
- Produce systems for operations and maintenance
- identify and record a clear structure of responsibility
for implementing and reviewing procedures to manage the risk
associated with legionella within building systems
- produce and complete a site log book to aid risk
management and record procedures in place
- ensure all staff responsible for maintenance
of relevant systems are suitably trained or instructed on how
to minimise the risks of legionella growth and any precautions
necessary when maintaining particular systems
- set in place a structured programme of maintenance,
testing, inspection and disinfecting
- ensure all appropriate operating and maintenance
documentation is easily available and that any necessary information
is reproduced for the legionella site logbook
- Consider installation improvements
- the risk assessment should highlight recommended
installation changes, such as the installation of destratification
pumps on hotwater generators. A pragmatic- approach is required.
It is not expected that an older system be replaced due to a
small risk. Capital outlay needs to be compared to order of
risk so that a rational approach can be adopted.
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Growth
The following conditions affect ' the growth of
Legionella
- water temperatures in the range 20 to 45°c.
It does not survive at temperatures above about 60°C
- sediment, sludge, scale and organic matter can
act as a source of nutrients, as can other organisms in water
such as other bacteria and algae. The slime, or biofilm, that
often forms on the surface of water, provides favourable conditions
for growth
- biofilms, sludge, corrosion etc can adversely
affect some treatment methods.
Systems.that eject water as an aerosol or as droplets
pose the biggest risk, as water in this form can be more easily
inhaled.
Risk Assement
A facilities manager is faced with four major risk
areas
- water systems incorporating cooling towers and
condensers
- hot- and cold-water services
- spray humidifiers that create a spray of water
droplets and in which the water temperature is likely to exceed
20°C
- spa baths and pools in which warm water is deliberately
agitated and recirculated.
Other plant and system containing water which is
likely to be in the temperature range 20 to 45°c and which may
release a spray or aerosol during operation or when being maintained
may also, present a risk.
The new HSE approved Code of Practice requires that
'a suitable and sufficient assessment should - be carried out
to identify and assess the risk of Legionellosis from work activities
and water sources on the premises and any precautionary measures'.
Our experience is that operational issues are the
easiest, less costly and the most effective to implement in minimising
and controlling risk. Once they have been addressed, full consideration
can be given to the installation.
In the UK, the primary regulations regulating the
employer's responsibilities in respect of Legionnaires' Disease
are the `Health & Safety at Work etc Act 1974' (as amended) and
the `Control of - Substances Hazardous to Health Regulations 1999'.
The new HSE document provides, guidance on the requirements
of this legislation. The code does not, however, address the technical
aspects of controlling the risk, which can be found in various
information published by Government departments, trade associations
and CIBSE.
For more details and advice contact maintenance@corbyrefrigeration.co.uk
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Corby
Refrigeration, Gordon House, Dale Street, Corby, Northamptonshire, NN17
2BQ UK
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Close control or Comfort
