Minimising the risk of Legionnaires' disease

65 Pages·2013·1.53 MB·English

Minimising the risk of
Legionnaires’ disease
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ISBN 978-1-906846-33-6
The Chartered Institution of Building Services Engineers
222 Balham High Road, London SW12 9BS
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Minimising the risk of
Legionnaires’ disease
Legionnaires’ disease
CIBSE TM13: 2013
CIBSE TM13: 2002
CIBSE TM13: 2013
CIBSE TM13: 2002
The Chartered Institution of Building Services Engineers
222 Balham High Road, London SW12 9BS
The Chartered Institution of Building Services Engineers
222 Balham High Road, London SW12 9BS
4
3,
1
0
2
6/
2/0 The rights of publication or translation are reserved. Foreword
1
m
p No part of this publication may be reproduced, stored in a retrieval system or These Technical Memoranda offer guidance on the appropriate design, installation,
2:09 tInrasntistumtiitotne.d in any form or by any means without the prior permission of the commissioning, operation and maintenance procedures necessary to minimise the risk of
1 infection by Legionella from water systems within a building. Principles are highlighted,
g, and practitioners in these fi elds are encouraged to apply them to their own particular
or © April 2013 (fourth edition) The Chartered Institution of Building Services
e. building services applications.
s Engineers London
b
@ci While the emphasis is on engineering, it is important to recognise that the best engineering
Registered charity number 278104
n solutions can fail, and have failed, if their operation and implementation are not managed
o
milt ISBN 978-1-906846-33-6 effectively. Some indications of how to implement effective management procedures are
d included.
n,
o This document is based on the best knowledge available at the time of publication.
Milt However no responsibility of any kind for any injury, death, loss, damage or delay It has been over 10 years since TM13 (CIBSE, 2002) was last reviewed. While some aspects
of the guidance have changed signifi cantly, in light of the legal, environmental and
e however caused resulting from the use of these recommendations can be accepted
ell technological advancements that have occurred, advice in other areas has remained
ni by the Chartered Institution of Building Services Engineers, the authors or others unchanged.
Da involved in its publication. In adopting these recommendations for use each
adopter by doing so agrees to accept full responsibility for any personal injury,
In the fi elds of water conservation and the environment in particular, new systems and
death, loss, damage or delay arising out of or in connection with their use by or on
services have been introduced and, no doubt, further developments will take place. It would
behalf of such adopter irrespective of the cause or reason therefore and agrees to
be impossible therefore to list and categorise all potential sources of hazard in relation to
defend, indemnify and hold harmless the Chartered Institution of Building Services
Legionella and building services. What the authors have sought to do is to cover in detail the
Engineers, the authors and others involved in their publication from any and all
processes associated with the more commonly encountered or potentially higher risk
liability arising out of or in connection with such use as aforesaid and irrespective
systems and the principles that should be considered for the effective management of all
of any negligence on the part of those indemnifi ed.
other water systems in buildings.
Project management, editing, layout, typesetting and printing by
The authors are also aware that specifi c industry and sector guidance is available and again,
The Lavenham Press Ltd., Lavenham, Suffolk CO10 9RN
where appropriate, this has been referenced. This list is not exhaustive, however, and the
information referenced has been chosen to best represent the intended audience of this
Cover illustration: © Chepko Danil Vitalevich, sourced through Shutterstock.com
publication. It is hoped that the appeal of the document and its usefulness will extend
beyond this group, however.
Concerns about the control of Legionella are becoming an ever more signifi cant public
health issue internationally. This update provides a reference to aspects of requirements or
guidance that exist outside the UK. While some of the governing principles for managing
the risks may be different, many similar themes are evident; the processes described in this
guidance will provide a valuable additional tool for supporting compliance beyond the UK.
Note from the publisher
TM13 Working Group
This publication is primarily intended to provide guidance to those responsible
for the design, installation, commissioning, operation and maintenance of Greg Davies (Assurity Consulting) (Chairman)
building services. It is not intended to be exhaustive or defi nitive and it will be
Giles Green (Zeta Compliance Services Ltd)
necessary for users of the guidance given to exercise their own professional
judgement when deciding whether to abide by or depart from it. John Lee (Leegionella Ltd)
Robert Macleod-Smith (RIMS Consulting)
Any commercial products depicted or described within this publication are
included for the purposes of illustration only and their inclusion does not John Newbold (HSE)
constitute endorsement or recommendation by the Institution.
Martin Shouler (Arup)
Chris Wilding (Ashland Water Technologies)
Julian Williams (Tower Systems Ltd)
Sanaz Nazemi Agha (Secretary)
Acknowledgements
The Institution is grateful to Ian Fellingham (IF Associates Ltd), Mike Iddon
(Piscean Analytical) and Paul McDermott (HSE) for kindly reviewing the draft
prior to publication.
Cooling tower schematics in Section 4 by courtesy of Baltimore Aircoil International.
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The rights of publication or translation are reserved. Foreword ilto
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No part of this publication may be reproduced, stored in a retrieval system or These Technical Memoranda offer guidance on the appropriate design, installation, , dm
transmitted in any form or by any means without the prior permission of the
Institution. commissioning, operation and maintenance procedures necessary to minimise the risk of ilto
infection by Legionella from water systems within a building. Principles are highlighted, n
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and practitioners in these fi elds are encouraged to apply them to their own particular
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© April 2013 (fourth edition) The Chartered Institution of Building Services building services applications. ib
s
Engineers London e
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While the emphasis is on engineering, it is important to recognise that the best engineering rg
Registered charity number 278104 solutions can fail, and have failed, if their operation and implementation are not managed , 1
2
effectively. Some indications of how to implement effective management procedures are :0
ISBN 978-1-906846-33-6 9
included. p
m
This document is based on the best knowledge available at the time of publication. 1
It has been over 10 years since TM13 (CIBSE, 2002) was last reviewed. While some aspects 2
However no responsibility of any kind for any injury, death, loss, damage or delay /0
of the guidance have changed signifi cantly, in light of the legal, environmental and 6
however caused resulting from the use of these recommendations can be accepted technological advancements that have occurred, advice in other areas has remained /20
by the Chartered Institution of Building Services Engineers, the authors or others 1
unchanged. 3
involved in its publication. In adopting these recommendations for use each , 4
adopter by doing so agrees to accept full responsibility for any personal injury,
In the fi elds of water conservation and the environment in particular, new systems and
death, loss, damage or delay arising out of or in connection with their use by or on
services have been introduced and, no doubt, further developments will take place. It would
behalf of such adopter irrespective of the cause or reason therefore and agrees to
be impossible therefore to list and categorise all potential sources of hazard in relation to
defend, indemnify and hold harmless the Chartered Institution of Building Services
Legionella and building services. What the authors have sought to do is to cover in detail the
Engineers, the authors and others involved in their publication from any and all
processes associated with the more commonly encountered or potentially higher risk
liability arising out of or in connection with such use as aforesaid and irrespective
systems and the principles that should be considered for the effective management of all
of any negligence on the part of those indemnifi ed.
other water systems in buildings.
Project management, editing, layout, typesetting and printing by
The authors are also aware that specifi c industry and sector guidance is available and again,
The Lavenham Press Ltd., Lavenham, Suffolk CO10 9RN
where appropriate, this has been referenced. This list is not exhaustive, however, and the
information referenced has been chosen to best represent the intended audience of this
Cover illustration: © Chepko Danil Vitalevich, sourced through Shutterstock.com
publication. It is hoped that the appeal of the document and its usefulness will extend
beyond this group, however.
Concerns about the control of Legionella are becoming an ever more signifi cant public
health issue internationally. This update provides a reference to aspects of requirements or
guidance that exist outside the UK. While some of the governing principles for managing
the risks may be different, many similar themes are evident; the processes described in this
guidance will provide a valuable additional tool for supporting compliance beyond the UK.
Note from the publisher
TM13 Working Group
This publication is primarily intended to provide guidance to those responsible
for the design, installation, commissioning, operation and maintenance of Greg Davies (Assurity Consulting) (Chairman)
building services. It is not intended to be exhaustive or defi nitive and it will be
Giles Green (Zeta Compliance Services Ltd)
necessary for users of the guidance given to exercise their own professional
judgement when deciding whether to abide by or depart from it. John Lee (Leegionella Ltd)
Robert Macleod-Smith (RIMS Consulting)
Any commercial products depicted or described within this publication are
included for the purposes of illustration only and their inclusion does not John Newbold (HSE)
constitute endorsement or recommendation by the Institution.
Martin Shouler (Arup)
Chris Wilding (Ashland Water Technologies)
Julian Williams (Tower Systems Ltd)
Sanaz Nazemi Agha (Secretary)
Acknowledgements
The Institution is grateful to Ian Fellingham (IF Associates Ltd), Mike Iddon
(Piscean Analytical) and Paul McDermott (HSE) for kindly reviewing the draft
prior to publication.
Cooling tower schematics in Section 4 by courtesy of Baltimore Aircoil International.
4
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2
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2/0 Editor Contents
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2: 1 Legionnaires’ disease: background
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@ci Ken Butcher
1.3 Multiplication factors 3
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Hywel Davies
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2 Regulatory framework 5
CIBSE Head of Knowledge
2.1 UK legislation 6
Nicolas Peake 2.2 UK codes of practice 6
2.3 Other sources of guidance 7
3 Risk management 7
3.1 Background 7
3.2 Design and specifi cation 8
3.3 Commissioning 9
3.4 Operation and maintenance 9
3.5 Quality management 10
3.6 Microbiological testing 10
3.7 Record keeping 12
4 Evaporative cooling applications 12
4.1 Introduction 12
4.2 Design 14
4.3 Operation 20
4.4 Control 25
5 Hot and cold water services 26
5.1 Introduction 26
5.2 Cold water services systems 27
5.3 Hot water services (HWS) systems 29
5.4 Small-scale, non-recirculating HWS systems 34
5.5 Microbiological testing 35
5.6 Flushing 36
6 Spa pools, whirlpool spas and whirlpool baths 36
6.1 Introduction 36
6.2 System management 37
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1.6 Susceptibility of individuals 4 2/0
Hywel Davies 6
1.7 Determining the risks 4 /2
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2 Regulatory framework 5 , 4
CIBSE Head of Knowledge
2.1 UK legislation 6
Nicolas Peake 2.2 UK codes of practice 6
2.3 Other sources of guidance 7
3 Risk management 7
3.1 Background 7
3.2 Design and specifi cation 8
3.3 Commissioning 9
3.4 Operation and maintenance 9
3.5 Quality management 10
3.6 Microbiological testing 10
3.7 Record keeping 12
4 Evaporative cooling applications 12
4.1 Introduction 12
4.2 Design 14
4.3 Operation 20
4.4 Control 25
5 Hot and cold water services 26
5.1 Introduction 26
5.2 Cold water services systems 27
5.3 Hot water services (HWS) systems 29
5.4 Small-scale, non-recirculating HWS systems 34
5.5 Microbiological testing 35
5.6 Flushing 36
6 Spa pools, whirlpool spas and whirlpool baths 36
6.1 Introduction 36
6.2 System management 37
4
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e Appendix A1: Glossary 43
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and hot and cold water service systems
Appendix A3: Guidance for suspected outbreaks of Legionnaires’ disease 48
Appendix A4: System checklists 49
Appendix A5: International legislation, standards and sources of guidance 53
Index 56
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7 Other possible risk areas 39 Minimising the risk of Legionnaires’ disease ilto
7.1 Risk assessment 39 n, d
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7.2 Scheme of control 40
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8 Conclusions and further information 40 c
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References 41 .org
Standards 41 , 1
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Legislation 42 9
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1 Legionnaires’ disease: fever, which does not result in fatalities, and those infected m
Bibliography 42 recover with no residual ill effects. 12
background /0
6
Appendix A1: Glossary 43 Any illness caused by Legionella is known under the generic /2
0
term ‘legionellosis’. Although previously healthy people 13
Appendix A2: Emergency cleaning procedure for cooling towers 47 1.1 Introduction may develop Legionnaires’ disease, individuals who are , 4
particularly at risk include smokers, alcoholics and patients
and hot and cold water service systems
Legionnaires’ disease was first recognised in July 1976, with cancer, diabetes and chronic respiratory or kidney
when an outbreak occurred among delegates attending an disease. There is a distinctive age distribution, with those
Appendix A3: Guidance for suspected outbreaks of Legionnaires’ disease 48 American Legion convention in Philadelphia. The cause of over 50 years of age being most commonly affected; children
the outbreak eluded scientists for several months but, in are affected only rarely. Men are at greater risk than women
January 1977, the Centers for Disease Control and (3:1). Only a small proportion (usually less than 1%) of
Appendix A4: System checklists 49
Prevention, Atlanta, reported the isolation of the causative those exposed in outbreaks develop Legionnaires’ disease.
agent, a bacterium that they named Legionella pneumophila. In contrast, in outbreaks of Pontiac fever almost all of those
Appendix A5: International legislation, standards and sources of guidance 53 Diagnostic tests were developed and reviews of stored exposed develop disease and both sexes and all age groups
specimens in laboratories revealed earlier outbreaks of the are equally susceptible.
disease and sporadic cases dating back to the 1940s. This
Index 56
showed that the infection was not new, but had escaped Legionnaires’ disease may be treated effectively with
recognition because the causative organism does not grow appropriate antibiotics. The diagnosis of Legionnaires’
on the conventional media used to culture bacteria in disease can be fully established only by laboratory tests:
diagnostic laboratories.
— the organism can be cultured from sputum, blood,
bronchial washings or lung tissue
Legionnaires’ disease is an uncommon infection: in the
decade between 2000 and 2009 an average of 385 (range
— antigens derived from Legionella may be detected in
180–551) cases per annum in England and Wales were
urine and
reported to the Health Protection Agency (www.hpa.org.
uk). The disease is notifiable under the Health Protection — blood tests that measure the presence in serum of
(Notification) Regulations 2010 in England and Wales, and specific antibodies produced by the body to combat
the Public Health (Notification of Infectious Diseases) infection may be used.
(Scotland) Regulations 1988 (as amended). An occurrence
in the workplace must be reported under the Reporting of The enzyme-linked immunosorbent assay for the detection
Injuries, Diseases and Dangerous Occurrences Regulations of Legionella antigens in urine is well validated, available
1995 (RIDDOR) (see Section 2). Approximately 50% of the commercially and currently the most common method of
cases identified in the UK are associated with travel, mostly diagnosis. It is very specific and can provide a rapid, reliable
abroad but also within the UK. It is probable that some diagnosis during the acute phase of the illness, often much
cases of Legionnaires’ disease are not detected or reported. earlier than can be achieved by serological analysis of the
Estimates of the actual number of cases vary but intensive blood, which was previously the most common method of
studies of community-acquired pneumonia suggest that diagnosis. Tests for antibodies in serum can be used for
2–3% are Legionnaires’ disease (Anon, 1987; Lim et al., diagnosis but it can take several weeks to obtain a result as
200l). With approximately 200,000 cases of pneumonia successive blood samples at least two weeks apart are usually
reported per annum (p.a.), this suggests that the real required. Consequently, this test has now been largely
number may be as high as 4000–6000 cases p.a. Countries superseded by the urinary antigen test. Polymerase chain
with best surveillance report a case incidence of reaction (PCR) based methods which detect the presence of
approximately 20/million population p.a. (Joseph and DNA (the genetic material) from L. pneumophila and
Ricketts, 2010), suggesting that England and Wales should Legionella species in clinical specimens are increasingly
have 52 × 20 = 1040 cases p.a. used for diagnosis. The most commonly used method for
the detection of legionellae in environmental samples is
Legionnaires’ disease is an illness characterised mainly by culture but PCR-based methods are increasingly being
pneumonia. It begins quite abruptly with high fever, chills, applied.
headache and muscle pain. A dry cough soon develops, and
many patients suffer difficulty with breathing. About one- L. pneumophila is one member of a large genus of bacteria.
third of patients also develop diarrhoea or vomiting, and At least 50 other species of Legionella have been reported,
about half become confused or delirious. The case fatality and at least 15 serogroups of L. pneumophila have been
rate is about 12%, which is similar to that of most other described. L. pneumophila serogroup 1 is the organism most
types of pneumonia. Legionellae also cause a self-limiting commonly responsible for Legionnaires’ disease in the UK,
influenza-like illness without pneumonia called Pontiac but the other serogroups of this and at least 19 other species
4
3, 2 Minimising the risk of Legionnaires’ disease
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, 1 Figure 1 Divisions of Legionella
, 8 pneumophila
have been found to cause disease in humans. L. pneumophila Legionellae cannot grow by themselves but require the
serogroup 1 can be further divided into various groups (see support of other organisms to enable them to multiply.
Figure 1). They can grow inside protozoa, which not only support
their growth but can also protect them from adverse
Monoclonal antibody subgrouping has been developed for environmental conditions. In addition, some other algae
L. pneumophila serogroup 1 and studies have shown that and bacteria have been shown to support their growth. Like
one particular monoclonal antibody (3/1) distinguishes most other aquatic organisms legionellae grow in association
those strains most commonly associated with Legionnaires’ with other organisms on surfaces in a biofilm. A biofilm is
disease (Helbig et al., 1995). More discriminating molecular a thin layer of micro-organisms, which may form slime on
subtyping methods have been developed. One method, a surfaces in contact with water. Such biofilms, sludge and
consensus sequence-based typing (SBT) scheme based on scale can protect legionellae from temperatures and
the sequences of seven genes has been developed by concentrations of biocide that would otherwise kill or
collaboration between several European laboratories and is inhibit these organisms if they were freely suspended in the
now widely used internationally (Gaia et al., 2005; Ratzow water.
et al., 2007). This permits strains of clinical and
environmental origin to be compared in the investigation The association of legionellae with protozoa means that
of outbreaks and has largely superseded earlier typing they may be protected from normal water treatment
methods. A database of types and their origins is held processes and enter the town drinking water supply system.
centrally and can be accessed by workers all over the world, In addition, legionellae are commonly encountered
enabling them to compare their isolates with those isolated elsewhere in the environment. Thus, they may readily
in other laboratories and countries. enter any manufactured water system and may eventually
colonise it if conditions are appropriate.
The genus Legionella, including L. pneumophila serogroup
1, is found in aquatic environments, both natural and The incubation period (the time between exposure to the
artificial. They have been found in waters at temperatures organism and development of first symptoms) is normally
from below 0 ºC up to 60 ºC. The organism is found most between 2 and 10 days with a median of 6 to 7 days. Longer
commonly in hot water services, particularly in storage incubation periods of up to 16 days have been recorded for
calorifiers and evaporative cooling water systems that serve a small proportion of cases in some outbreaks and, extremely
air conditioning plants. Systems that are corroded or rarely, even longer (up to 22 days) for severely
contain debris or have evidence of organic fouling are more immunocompromised individuals. Person-to-person
likely to harbour the organism. Other factors that favour spread of the infection has not been documented.
growth of legionellae are stagnation of the system water
content and an appropriate temperature: multiplication The investigation of outbreaks of Legionnaires’ disease has
occurs between 20 ºC and 45 ºC with an optimum at between led to the identification of various sources of infection and
32 ºC and 42 ºC. routes of transmission. Sources of infection include:
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— oevpaepno raatnivde ccloonsdeden sceirrsc usietr vcinogo lianigr ctoonwdeirtsio nainndg The duration of exposure may also have some influence. ilto
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and process cooling systems It is worth considering these factors in a little more detail , d
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because they provide the clues to the prevention or control
— hot water and, more rarely, cold water services of the risk of infection. ilto
systems in large buildings such as hospitals and n
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generated by running taps and showers and flushing 1.3 Multiplication factors s
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toilets where the water is contaminated) .o
— spa pools (sometimes called whirlpool spas) The optimum temperature for multiplication of L. rg, 1
pneumophila in the laboratory is between 32 ºC and 42 ºC. 2
— fountains with a particularly fine spray in an The bacteria can survive at higher temperatures, but the :09
enclosed space survival time decreases from a few hours at 50 ºC to a few pm
minutes at 60 ºC; at 70 ºC the organism is killed virtually 1
— machine tool cutting coolant 2
instantaneously. Below 37ºC the multiplication rate /0
6
— misting devices used for humidifying vegetables decreases, and it can be considered insignificant below /2
and meat 20 ºC. The organisms can survive in a dormant state at 01
3
— untreated natural hot spring spa water used for much lower temperatures, and will return to active , 4
multiplication whenever more favourable temperatures
inhalation, bathing or showering
occur. Legionellae have been found in water systems with a
— non-disposable nebulisers used for respiratory wide range of pH values.
therapy
— industrial effluent treatment plants Steam humidification
100
— potting composts.
No viable
Legionella
Many other water systems can contain legionellae (for
80 LTHW heating system
example, rainwater harvesting, grey water and irrigation
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Legionellosis is caused by inhalation of an aerosol of e
T Spas, showers
bacteria generated from water droplets (compost is a 40 L e g i o n e l la will
possible exception). Less commonly, it may also be caused Cold water services Cooling multiply
Fire sprinklers towers
by aspiration of Legionella-contaminated water (i.e. by
contaminated water ‘going down the wrong way’ and 20
entering the lungs). Spray humidifier
L e g i o n e l la will
Mains cold water, air cooling coil remain dormant
condensate and chilled water systems
Survival of the bacteria in an aerosol will depend on a
0
number of factors, including ambient temperature, relative
humidity, sunlight and transportation by wind. Increasing risk of multiplication ofLegionella
Figure 2 System design/operating temperatures and multiplication of
1.2 Risk of infection Legionella
The risk of infection from a water system is dependent on a
number of factors, including:
Typical design temperatures for water in building services
— the presence of one or more multiplication factors are illustrated in Figure 2. Cooling towers and spas are
that allow legionellae to grow from low to high designed to operate at temperatures that happen to be
numbers; such factors include the water favourable for the growth of legionellae, and therefore such
temperatures within the system, low flow rates and/ systems require regular biocidal treatment. Similarly, hot
or low turnover (stagnation) and the presence of water services may contain deadlegs, blind ends and other
certain materials, such as natural rubbers, some stagnant zones that could hold water for long periods at the
sealants and certain plastics, which may serve as a temperatures at which legionellae multiply. Cold water
nutritional source within the system services may also reach temperatures likely to encourage
multiplication of the bacteria (for example, unlagged
— the possibility that aerosols may be formed and
pipework close to heat sources, limited service areas and
released within part of the water system
increasing thermal performance of buildings).
— the concentration of legionellae in the aerosol and
the size of the aerosol particles; the risk increases
1.4 Aerosol generation
the higher the concentration of bacteria and the
smaller the size of particle (smaller particles are
Contaminated water presents a risk of actual infection
more dangerous because they can penetrate more
when it is dispersed into the air as an aerosol. Small particles
deeply into the lung)
will remain airborne for long periods, and small droplets of
— the susceptibility to Legionella infection of the 5 µm diameter or less penetrate deeply into the lung and
people exposed to the aerosol. cannot be expelled easily. However, larger droplets can