CODE OF PRACTICE LEGIONNAIRES DISEASE
1. LEGIONNAIRES’ DISEASE
1.1 WHAT IS LEGIONNAIRES’ DISEASE?
The term “Legionnaires’ Disease” was coined in 1976 after a dramatic outbreak of serious
respiratory disease at a convention of the American Legion of Pennsylvania led to the discovery
of a new disease entity and, eventually, to the identification of the responsible bacteria,
Legionella pneumophila. At least 39 species and 61 serogroups have been identified. L.
pneumophila, is the species most commonly identified in cases reported both in Australia and
overseas, causing approximately 70% of all cases of Legionnaires’ Disease.
Illnesses caused by any Legionella species are called Legionellosis. “Legionnaires’ Disease” is
the term used for the disease caused by L. pneumophila. However, “Legionnaires’ Disease” has
become the familiar term used to refer to any severe form of pneumonia which is caused by any
Legionella species such as Legionella longbeachae which may occur in potting mix, soil, peat,
mulch and garden composts.
This form of pneumonia may be accompanied by involvement of other organs such as the brain,
causing confusion; the bowel, causing diarrhoea; and the kidneys, causing kidney failure.
Symptoms include rapid onset of high fever, non-productive cough, chills, headache and general
‘aches and pains’.
The incubation period, that is the time between infection and signs and symptoms appearing, is
usually 2-10 days. Less than 5 per cent of the exposed persons are likely to become ill. The
Western Australian experience is that 10% of these people who are admitted to hospital, die.
Diagnosis is generally made by means of serological blood tests and/or identifying the organism
in sputum and respiratory secretions. A urinary antigen test is also available for Legionella
pneumophila serogroup 1.
It is estimated that 1 per cent of pneumonia cases admitted to hospitals are, in fact, suffering
from Legionnaires’ Disease. No vaccine is currently available. The disease is resistant to
penicillin but responds to treatment with other antibiotics such as erythromycin and rifampicin.
Pontiac fever, also caused by species of Legionella, is an influenza-like illness with symptoms
including fever, chills and headache. The incubation period ranges from 4 hours to 3 days. Up to
95 per cent of the exposed persons become ill. Pneumonia does not occur and full recovery can
be expected.
Many infections by L. pneumophila do not result in recognisable signs and symptoms.
Antibodies have been found in up to 25% of adults tested. This suggests that up to 1 in 4 adults
have been infected at some time in their life but have not necessarily developed any symptoms.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
1.2 HOW IS IT TRANSMITTED?
Since Legionella bacteria may be found in many natural water sources, as well as in the
circulating water of cooling towers, contact between humans and the bacteria seems to be almost
inevitable. Under favourable conditions, very high concentrations of the bacteria can be present in
the water of cooling towers.
Legionnaires’ Disease is usually transmitted via inhalation of aerosol mists which allows the
bacteria to be transported into the lungs.
Drinking water and washing in water containing low numbers of Legionella bacteria is not known
to result in infection. Person-to-person transmission is also not known to occur. There has been
evidence of transmission from ingesting the bacteria, however, this is rare.
1.3 SOURCES OF INFECTION
Legionella bacteria are widely distributed natural inhabitants of ponds, streams, lakes, rivers, soil,
mud and underground water. The bacteria thrive in warm moist conditions. Although it has been
found in waters with temperature ranging up to 60oC, significant multiplication of the bacteria is
generally restricted to temperatures of 20oC to 45oC and particularly to the range of 35oC to
43oC. Long exposure at 50oC or shorter exposure at higher temperatures is sufficient to kill the
bacteria.
Legionella bacteria may accumulate in cooling towers, evaporative condensers, hot water
systems, spas, humidifiers, and nebulisers.
Outbreaks of Legionnaires’ Disease have been associated predominantly with inhalation of
contaminated aerosols from cooling towers and hot water systems including showers and
whirlpool spas. People can be exposed to these aerosols in homes, workplaces, hospitals, public
places and buildings.
Infection with Legionella longbeachae may occur from inhalation of airborne particles from
potting mix.
The growth of L. pneumophila is promoted by the presence of other micro organisms. Certain
single-cell organisms are able to amplify these bacteria in cooling towers as well as to protect
them from adverse conditions, including the biocidal action of water treatment chemicals. Other
bacteria and algae can provide nutrients for L. pneumophila. Sediments can stimulate the growth
of the environmental micro flora which, in turn, stimulate the growth of L. pneumophila.
Investigations of the relationship between the chemical environment in plumbing systems and
growth of L. pneumophila has shown that low concentrations of certain metals such as iron, zinc
and potassium enhance proliferation of the species. Hence, the metal components and corrosion
products of plumbing systems (eg. galvanised iron) may play a role in promoting growth of these
bacteria.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
The constituents of certain types of rubbers used in rubber fittings in the system can also support
the multiplication of L. pneumophila.
The proliferation of L. pneumophila occurs mainly in water systems as a result of the interrelationships between temperature, environmental micro flora and sediments and the chemical
composition of waters in man-made systems.
In general, the sources of Legionella bacteria implicated in overseas outbreaks of Legionnaires’
Disease have been traced to large air conditioning plants or to hot water distribution systems
which have been incorrectly commissioned or have been poorly maintained. The release of
aerosols from water distribution systems may occur from shower heads or from water splashing
in hand basins or baths. Standby installations would also be sources of infection if they are used
infrequently and not included in the general maintenance routine.
Potential sources of infection could include evaporative air conditioners, artesian bores,
decorative fountains, fixed garden sprinklers, car washes, and above ground storage tanks which
feed aerosol generating equipment, although no known documented cases have been recorded to
date.
Many cases of Legionnaires’ Disease are sporadic and the source of the organisms is very
difficult to determine. In Australia major outbreaks have been traced to cooling towers and to
evaporative condensers associated with refrigeration systems. Small numbers of cases have been
associated with hot and cold water services, spa pools, the coolant in industrial milling machines,
high pressure cooling and cleansing processes, humidification devices and with potable water
aerosols from shower heads and other devices.
Window or wall unit refrigerated air conditioners have not been associated with Legionnaires’
Disease because they use refrigerated air instead of evaporated water.
1.4 DEGREE OF RISK
Infection may occur, particularly in susceptible people, from exposure to aerosols containing
large concentrations of pathogenic bacteria. The mere presence of Legionella bacteria in water
is not necessarily a cause for concern.
Proliferation of L. pneumophila is promoted by:
•
a wet warm environment (range 25-42oC);
•
optimum temperature (35-37oC);
•
stagnation or low water turnover;
•
high microbial concentration including algae, amoebae, slime and other bacteria;
•
presence of biofilm, scale, sediment, sludge, corrosion products or organic matter; and
•
presence of certain materials such as natural rubber fittings which may be a nutrient
source.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
Factors increasing the likelihood of illness from Legionella infection:
•
concentration of Legionella: sufficient bacteria must be present in an aerosol to cause an
infection;
•
aerosol particles (< 10 microns1 ) small enough to be inhaled into the lung;
•
susceptibility of the individual such as the middle-aged and elderly, smokers, those with
chronic illnesses such as diabetes, chronic lung, heart or kidney disease, cancer,
immunosuppression and excessive alcohol intake; and
•
cleaning cooling towers, spas or handling potting mix or soils.
The risk of contracting Legionnaires’ Disease can be reduced to a very low level by careful
design, construction and good maintenance of cooling towers, air-handling systems, hot water
services and other potential sources of aerosol.
1.5 REDUCING THE RISK
1.5.1 Procedure for dealing with potential infection
The following flow chart provides an example of a procedure which employers, in consultation
with employees, can adopt to address the issue of potential infection in the workplace.
Step 1: Identify potential sources of infection
u
t
Are employees located near spray
formations?
u
Step 2: Assess the risk of infection
t
Step 3: Control the risk
Do you have air cooling towers,
humidifiers, water services, etc?
Is the equipment manufactured to
Australian Standards?
Is the system regularly maintained and
cleaned?
u
Appropriate maintenance and cleaning
program in place.
If necessary, water testing and
treatment.
It is important that the steps implemented are regularly reviewed to ensure the controls in place
are adequate.
1 There are 1000 microns in one millimetre.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
1.5.2 Consultation and cooperation
The Occupational Safety and Health Act requires employers to consult with safety and health
representatives, if any, and provide information to employees. Employers should follow a
consultation procedure that has been agreed upon by all parties in the management and reduction
of risk arising from hazards, such as biological contaminants, that may cause Legionnaires’
Disease.
For employers, the relevant sections of the Occupational Safety and Health Act are Section 19
for the general duty to consult and cooperate with safety and health representatives (if any) and
other employees at the workplace, and Section 35 for specific duties that the employer has in
relation to safety and health representatives.
For employees, Section 20 requires them to comply with instructions given by the employer to
ensure the employees’ safety and health and to cooperate with the employer in the carrying out of
any obligations required under the Act, including the functions of a safety and health
representative.
2. GENERAL PRINCIPLES OF DESIGN,
INSTALLATION, OPERATION AND
MAINTENANCE
To reduce contamination of cooling towers, air-handling systems and hot, warm and cold water
services, attention must be paid to their design, installation, operation and maintenance
procedures. The aim is to minimise micro-organism growth in artificial environments and, if
possible, to reduce the likelihood of inhaling any potentially contaminated aerosols.
• Siting of systems. Attention should be given to:
- design of enclosures;
- location of building air inlets, including windows which open;
- direction of prevailing winds and any localised wind patterns;
- height and design of adjacent structures;
- proximity of other discharges such as kitchen exhausts; and
- future planned developments.
• Design features should facilitate cleaning, control bacterial growth and
minimise drift carryover. Attention should be paid to:
- provision for shutdown for maintenance;
- convenient and safe accessible openings for maintenance;
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CODE OF PRACTICE LEGIONNAIRES DISEASE
-
components which minimise corrosion and can be easily removed;
minimal internal components such as structural brackets which can collect sediment;
materials compatible with the use of disinfectant and hosing with water jets;
sumps that can be readily drained;
efficient drift eliminators;
surfaces which can be readily cleaned;
protection of wetted surfaces from direct sunlight; and
adequate standby facilities where continuous operation is necessary.
Commissioning, operating, maintaining, cleaning, decontamination and other procedures should
be designed to minimise the risk to personnel working on or in the vicinity of cooling towers and
other potential sources of Legionella bacteria. The installations should be examined under
normal working conditions for signs of microbial growth, algae, water leaks, splashing and
blockages or restrictions at air inlets.
If aerosol sprays are created, then the installation should be switched off when inspecting or
carrying out maintenance. If this is not practicable, then particulate filters, or equivalent
respiratory protection should be worn to minimise the risk of inhaling water droplets
contaminated by Legionella bacteria.
The following information sets out the minimum requirements for the correct operation and
regular routine maintenance of cooling towers, air-handling systems and hot, warm and cold
water systems.
Water systems should be disinfected, drained, cleaned and then disinfected again when the
installation:
•
is being started up for the first time;
•
has been out of use and has not been dry; or
•
has been extensively modified or disturbed.
Cleaning may also be necessary at regular intervals if the system, the premises or the results of
monitoring indicate it is necessary to do so. In such cases, it is important to ensure that all parts
of the system are disinfected, not just those which are readily accessible.
Some cleaning methods may create large amounts of spray (ie. high pressure water jetting). If
this cannot be avoided, and particularly if cleaning is done in confined spaces, then personnel
should wear air line or self-contained breathing apparatus (SCBA) unless it is not safe or
practicable to do so. This is recommended as filter respiratory protective equipment has not
been specifically tested for use against aerosols containing Legionella bacteria. Other ways to
reduce the risk to maintenance personnel include decontamination and routine cleaning of
cooling towers by chlorination of the tower water prior to any physical cleaning being
undertaken.
Systems are necessary which minimise the risk of scalding and reduce the Legionella risk
associated with the storage of warm water. These may include heat exchange systems, ultraviolet
light systems, anti-scald safety valves and self-draining valves.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
Cooling water systems should be provided with automatically regulated water treatment systems
for effective management of corrosion, scaling, fouling and microbial growth.
The effectiveness of the water management system (including water treatment) should be assessed
at least monthly.
The employer’s responsibilities are not absolved by contracting out the maintenance, cleaning and
testing. Employers should monitor the contractor’s performance.
2.1 MANUALS AND RECORDS
Operating and maintenance manuals and maintenance records should be available for all
workplace equipment and systems which are the subject of this code of practice. The operating
and maintenance specifications and manuals should be provided by the manufacturer, designer,
supplier or importer. It is recommended maintenance records are also kept by householders for
their domestic air conditioners, water systems and spas.
Operating and maintenance manuals and records should at least include the following:
•
•
•
•
•
•
physical details, including drawings, of the equipment and systems;
manufacturers’ recommendations on maintenance, including water treatment maintenance
and management;
recommended cleaning methods and dismantling instructions;
operating and shut-down procedures;
date, item of equipment or system and nature of service performed; and
the name of the person or company performing the service.
In workplaces, these manuals and records should be readily available for inspection.
More Information
Further information on the design, installation and commissioning of air-handling and water
systems of buildings may be obtained from AS/NZS 3666, Air-handling and water systems of
buildings – Microbial control, Part 1: Design, installation and commissioning.
SAA/SNZ HB32, Control of microbial growth in air-handling and water systems of buildings,
is a handbook which provides users with additional information to support the specific
requirements of AS/NZS 3666, Parts 1 and 2.
Further information on the requirements for installation of water heaters and hot water
reticulation can be found in AS 3500, National Plumbing and Drainage Code, Part 4, Hot water
supply systems.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
3. COOLING TOWERS
Cooling towers and associated equipment encompasses devices used for lowering the
temperature of water by evaporative cooling where the atmospheric air passes through spray
water resulting in an exchange of heat. This includes a device incorporating a refrigerant or water
heat exchanger.
3.1 DESIGN AND INSTALLATION
• Cooling towers should be designed and installed with the following general features:
- located so that exhaust is discharged away from occupied areas, pedestrian thoroughfares,
air intakes (including lift vents), building openings and areas of traffic movement;
- located so as to avoid contamination by the exhaust discharges from other air-handling
systems, such as kitchen exhaust or other cooling towers;
- cooling tower enclosures must not interfere with the required airflow through the tower
nor result in the recirculation of discharge air;
- located and oriented so that direct sunlight is excluded from the wetted areas of the
cooling tower;
- easy and safe access for maintenance, particularly for cleaning purposes;
- provisions for shutdown to facilitate maintenance;
- accessible water treatment units, where installed;
- constructed of corrosion-resistant material;
- drift eliminators to facilitate ease of inspection, cleaning and maintenance. Drift
eliminators should be designed for in situ cleaning or capable of being withdrawn, without
damage, for cleaning and should extend across the air stream. Air bypass and splash out
from the cooling tower should also be prevented;
- rapid draining facilities;
- automatic or permanent bleeds to waste, to limit the build-up of dissolved salts in the
water; and
- a maximum of 0.02% to be lost from the water circulation rate as drift.
• Cooling towers and associated equipment should be chemically cleaned and thoroughly flushed
before being brought into service.
3.2 OPERATION AND MAINTENANCE
• Cooling towers should be operated and maintained using the following procedures:
- inspected at least monthly as part of the regular maintenance routine;
- cleaned regularly as necessary but at intervals not exceeding six months. Cleaning should
include the physical cleaning of the cooling tower and disinfection and draining of the
entire water cooling system;
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CODE OF PRACTICE LEGIONNAIRES DISEASE
-
flushed and cleaned before start-up if only used seasonally;
all internal wetted surfaces, particularly their sumps and fill, cleaned by high pressure
water, steam or other effective methods; and
the operating conditions for the system operating pumps and the cooling tower fans
should be reviewed. Reducing the system operating water temperatures to the lowest
practicable value improves control of micro-organisms, including Legionella spp., and
usually improves operating efficiency.
• If the system is contaminated:
- treated with biocides before draining and cleaning; and
- decontamination shall be carried out when directed by the regulatory authority.
4. AIR-HANDLING SYSTEMS
An air handling system refers to a system designed for directing air in a positive and controlled
manner through specific enclosures by means of air-handling plant, ducts, plenums, air
distributing devices and automatic controls.
4.1 DESIGN AND INSTALLATION
• Air-handling systems should be designed and installed with the following general features:
- built from plans submitted for approval to building authorities, including a site survey
which shows details of the new installations, the adjacent buildings and prevailing wind
conditions. The site survey information should show details of existing cooling towers,
air intakes and natural ventilation openings of buildings adjacent to or facing the proposed
new installation;
- exhaust discharges which minimise cross-contamination with air intakes in the same
building or adjacent buildings. Exhaust discharges from air-handling systems should be
located to avoid cross-contamination with air intakes of cooling towers or any windows or
doors which may be opened in the same building or a nearby building. Prevailing wind
directions and wind effects should be taken into account in locating exhaust outlets;
- air intakes which are designed to eliminate the collection of airborne pollution or dust;
- no external lights near air intakes since these lights attract insects which could be drawn
into the system;
- provision for shutdown to facilitate maintenance;
- easy and safe access for maintenance, particularly including the air filter, where present.
Where installed, air filters should be selected and located so that access is available for
maintenance and the accumulation of moisture does not occur. Filter bypass should be
avoided;
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CODE OF PRACTICE LEGIONNAIRES DISEASE
-
-
corrosion-resistant air intakes and exhaust air outlets designed to minimise the entry of
rainwater and prevent the entry of birds, rodents and windblown material such as leaves and
paper;
use of trays, sumps, condensate and equipment drainage fan assemblies and duct work, as
required, to drain effectively any accumulating moisture in any air-handling systems;
the collection and discharge of moisture from sprays, atomisers or sponge pipes by
grading to an outlet to prevent pondage;
humidifiers located so as to prevent the accumulation of airborne debris and to optimise
the mixing of water vapour with air being humidified;
a control system so that the humidifier cannot be operated when the air-handling system is
switched off; and
use of a steam spray and avoidance of over-humidification or water stagnation in
humidifiers.
These air-handling installations (below) should be designed and installed with the following
features:
• Evaporative coolers:
- fabricated with access for maintenance and for ease of cleaning;
- air intakes located away from exhaust outlets and designed to eliminate the collection of
airborne pollution, dust or organic matter; and
- kept dry when not in use.
• Heat exchange coils:
- constructed of corrosion-resistant materials and installed in such a way that they can be
easily cleaned; and
- designed to effectively remove airborne condensate by grading to outlets to prevent
pondage.
• Terminal units:
- have a condensate tray and adequate drainage, so moisture is not re-evaporated by the
airflow through the system; and
- accessible for maintenance.
4.2 OPERATION AND MAINTENANCE
• Air-handling systems should be operated and maintained using the following procedures:
- air intakes and exhaust outlets inspected at least monthly and cleaned when necessary; and
- supply air filter media inspected and cleaned or replaced in accordance with the
manufacturer’s specifications. Where installed, air filters should be inspected monthly
and cleaned or replaced where necessary in accordance with the suppliers’ requirements.
The air-handling installations and components below should be operated and maintained using the
following procedures:
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CODE OF PRACTICE LEGIONNAIRES DISEASE
• Humidifiers:
- inspected monthly and cleaned where necessary for all types;
- cleaned before start-up if the system is shutdown on a seasonal basis;
- humidifiers should be located so as to prevent accumulation of airborne debris and
optimise the mixing of water vapour with air being humidified;
- the arrangement of the control system should be such that the humidifier cannot operate
when the air-handling system is switched off;
- over-humidification should be avoided in order to prevent precipitation of moisture within
the ducting;
- trays or sumps should be provided for the collection and discharge of condensate from
humidifiers with trays and sumps accessible for inspection and cleaning and graded to the
outlet to prevent pondage. Trays and sumps should be constructed from corrosion-resistant
materials with all internal corners and edges constructed to facilitate cleaning. Trays and
sumps should extend beyond all sides and corners of the humidifier to enable collection of
condensate or water under all operating and maintenance conditions;
- line strainers, valves, sparge pipes, spray nozzles and components of steam and spray
humidifiers discharging moisture into the airstream should be inspected monthly and
cleaned, where necessary. Associated sensors and controls should be maintained and
-
calibrated by qualified personnel in accordance with the suppliers’ requirements; and
tanks, trays and discharge devices of boiling and pan-type humidifiers should be inspected
monthly and cleaned, where necessary.
• Evaporative coolers, including ducted and mobile air conditioners found in the home
environment:
- components and ducts inspected at least annually and replaced or cleaned as appropriate.
Inspection and cleaning may need to occur more frequently for mobile units and in dusty
conditions;
- evaporative air coolers should be fabricated from corrosion-resistant materials;
- all internal corners and edges of trays and sumps should be constructed to facilitate
cleaning;
- evaporative air coolers should be located to avoid the ingress of contaminants from flues,
air exhausts, cooling towers, sewer vents, waste containers, and other sources of airborne
pollution. Prevailing wind directions, wind effects, multiple roof levels and arrangement of
adjacent structures should be taken into account in locating air intakes;
- drain lines should be uniformly and continuously graded downwards to prevent collection
of water. The drain lines should be trapped to seal against airflow. Drain discharges should
be located close to the equipment being served;
- trays or sumps should be provided for the collection and discharge of condensate and spray
water and should be accessible for inspection and cleaning and graded to the outlet to
prevent pondage;
- for other than sole occupancy dwellings, the following components should be inspected at
least every three months while the system is in use and maintained as indicated:
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CODE OF PRACTICE LEGIONNAIRES DISEASE
a)
b)
c)
d)
e)
-
sump drained and cleaned;
wetted pads cleaned every three months and replaced, where necessary;
water strainer cleaned, where necessary;
air filter, where fitted replaced; and
drainage system flushed with clean, fresh water.
evaporative air coolers, when not in use for periods greater than one month, should be
drained; and
where air conditioners are to be switched off for an extended period (ie. during the offseason) all water should be drained out and the filter pads and unit itself cleaned and dried.
Exposed units should be fitted with protective covers.
• Coils, trays, sumps, terminal units:
- coils, trays and sumps should be inspected monthly and cleaned where necessary;
- terminal units should be inspected annually and cleaned where necessary;
- heat exchange coils should be constructed from corrosion-resistant materials suitable for
the environment. Cooling coil design should ensure effective removal of airborne
condensate;
- trays or sumps should be provided for the collection and discharge of condensate and
-
spray water from cooling coils. Trays and sumps should be accessible for inspection and
cleaning and should be graded to the outlet to prevent pondage; and,
in cooling coil applications, trays and sumps should extend beyond all sides and corners of
the coil (e.g. extend under flanges and control valves) to enable collection of condensate
or water under all operating and maintenance conditions.
• Condensate drains, tundishes2 , traps;
- checked monthly for effectiveness and flushed; and
- for other than sole occupancy dwellings, ductwork and other air-handling plant comprising
the air-handling system should be serviced, unless otherwise specified, as indicated:
a)
coils inspected monthly, and cleaned when necessary;
b)
trays and sumps inspected monthly and cleaned, when necessary;
c)
condensate drains, tundishes, and traps checked monthly for effectiveness, and
drainage lines flushed clean;
d)
ductwork inspected annually in the vicinity of moisture-producing equipment and
e)
f)
selected access points and cleaned, when necessary; also, functioning of drainage
facilities checked annually and, where necessary, drains cleaned;
fans and fan coil units inspected annually for evidence of corrosion, wear on
flexible connections and drive belts, and for other deterioration, and cleaned or
repaired where necessary;
terminal units components inspected annually and cleaned, where necessary.
2 Tundishes – apertures which collect water before discharge into a drain or waste.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
5. WATER SERVICES
5.1 DESIGN AND INSTALLATION
Hot, Cold and Warm Water Services
• These water services should be designed and installed with the following general features:
- provision, in any water storage vessels, for inspection, cleaning, rapid drainage, rapid
refilling and measures to prevent the ingress of foreign matter;
- provision for shutdown for maintenance;
- easy and safe access for maintenance, including for water treatments;
- made with components which do not foster microbiological growth or react adversely to
chemicals; and
- a stand-by facility where the normal continuous operation is stopped for maintenance.
These water services should be cleaned either chemically or with hot water and thoroughly
flushed before being brought into service.
In addition to these features, the following features should apply:
• Hot water services:
- designed to heat water to 60oC or above.
• Warm (tepid) water services:
- designed to include one tank which heats water to at least 60oC and another tank which
holds cold water which is protected from sunlight or excessive local heat sources such as
hot vessels or pipes; and
- provision of preset thermostatic mixing valves to avoid scalding if the water is used for
showering or similar purposes.
• Cold water services:
- storage of cold water should protect the water from sunlight or excessive local heat
sources such as hot vessels or pipes; and
- hold only one day’s water supply to prevent stagnation.
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5.2 OPERATION AND MAINTENANCE
Hot, Warm and Cold Water Services should be operated and maintained using the following
procedures:
• Hot water services:
- inspected and, where possible, flushed at least annually and in accordance with the
requirements of the relevant authorities; and
- inspected monthly where water treatment units are installed.
• Warm water services:
- heated to at least 60oC once each month, and this temperature held for a period of one
hour; or
- inspected and, where possible, flushed at least annually as for hot water services.
• Cold water services:
- initially inspected and cleaned annually by chlorination and flushing.
Depending on the levels of corrosion, sludge and sediment experienced, the frequency of
cleaning may be altered thereafter.
6. EQUIPMENT MAINTENANCE OF
OTHER SOURCES OF INFECTION
Investigations of outbreaks of Legionnaires’ Disease, especially in the USA and UK, have
identified several sources of infection. Apart from these sources, which have resulted in
epidemic infection and have already been mentioned previously, the following sources, resulting
in sporadic infection, have also been identified. Information is provided on the minimum
operation and maintenance procedures required for these systems.
• Spas (Whirlpools)
Spas utilise warm water at approximately 38oC, with air and water jets producing turbulence and
creating aerosols. These aerosols are in the breathing zone of spa users and therefore likely to
be inhaled.
Test the spa water before use and maintain the water conditions with a pH of 7.2-7.8, with a
chlorine level of 2-4 mg/l or a bromine level of 4-8 mg/l.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
Operate the filter pump when dosing biocides, but not the air blower or venturi.
Use a test kit to check water conditions and biocide levels.
Filter the water for at least two hours every day, even if the spa is not in use. Always run the filter
for at least one hour after use.
Check and clean the filter regularly.
Remove at least 10% of the water weekly and replace it with clean tap water. Heavily used spas
will require removal of more water.
Keep spa surfaces clean, including the surrounds, tiles and cover.
• Water Based Metal Working Fluids
Metal working fluids are specially developed coolants and lubricating fluids used in the grinding,
cutting and drilling of metals. These coolants provide a good culture medium for microorganisms. Any equipment shut-down may lead to proliferation of micro-organisms, which can
occur more rapidly when the coolant is not circulated and separation of the oil-water emulsion
takes place.
The growth of micro-organisms can be controlled by the correct use of biocides.
• Respiratory Therapy Equipment
Portable room humidifiers and oxygen nebulisers (spray generators) are commonly used on
patients with underlying lung disease, most of whom have a weakened defence against infection.
Instances have occurred where tap water, from which Legionella was isolated, had been used in
both pieces of equipment.
Only sterile water should be used in these devices.
With oxygen nebulisers, disposable parts should be used. Otherwise the nebulisers should be
emptied after each use, the parts dismantled and washed with soapy water. The parts should then
be washed and dried in a dish washing machine where the temperature of the hot water is over
70oC. They should then be stored dry and should never be rinsed with tap water.
If the equipment is continuously used by a long-term patient, it should be disinfected in this
manner at least weekly.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
7. WATER TREATMENT AND TESTING
7.1 WATER TREATMENT
The most effective measures for reducing the risk to persons of acquiring Legionnaires’
Disease can be achieved by good design, regular inspection and maintenance. Biocides should
never be used as substitutes for good housekeeping.
Cooling towers that are not properly designed or maintained, may require the use of biocides
combined with thorough cleaning. General, broad-spectrum biocides which are used to control
algae and slime will control organisms associated with the growth of Legionella. Chlorination,
for example, can be used if disinfection is necessary.
The problems that biocides may cause include effects on workers handling the chemicals and on
the general public. There may be potential environmental consequences where the ‘drift’ pollutes
the immediate atmosphere, for example, city streets between tall buildings. Biocides that find
their way into air conditioning systems may affect large numbers of people. Irritation/
sensitisation and chronic toxicity effects are of greatest concern. Chemicals used in open
cooling towers should be of low toxicity and should be assessed before introduction, as would
any industrial chemical.
Biocides used in regular cleaning and disinfection should have a range of properties:
•
effective against a wide spectrum of bacteria, algae, protozoa and fungi;
•
maintain effectiveness when in contact with contaminants or substances in the systems;
•
quick acting, long lasting effect;
•
non-toxic to mammals;
•
environmentally acceptable in tower drift and water discharge;
•
effective at a low concentration over the range of pH encountered in cooling tower water;
•
compatible with other chemicals used;
•
not cause deterioration of materials it contacts;
•
penetrate foam, sludge, slime and scale within the system without foaming;
•
inexpensive; and
•
easily transported, handled and can be applied on-site.
The ideal biocide probably does not exist.
7.1.1 Disinfection
The two most commonly used biocides for disinfection of cooling towers are free chlorine and
quartenary ammonium compounds. New biocides continue to be developed. Biocides should be
used in accordance with the manufacturer’s directions.
These are not necessary for regular cleaning.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
Ongoing maintenance should occur according to the procedures outlined elsewhere in this code.
One of the difficulties associated with biocides is the lack of biofilm penetration. It may be
necessary to incorporate a dispersant to assist in the disinfection of cooling tower systems.
Water treatment should be carried out by, or under the direction of, suitably trained and
experienced persons. Chemicals should be handled with care by personnel wearing appropriate
protective clothing, including goggles and gloves, to prevent contact with these agents.
Chemicals such as biocides, cleaning agents, corrosion inhibitors, anti-sludging chemicals, acids
and alkalis may be used in operating, cleaning and decontamination procedures. Material Safety
Data Sheets should be obtained for each chemical agent used and the recommended preventative
measures and first aid procedures followed.
Personnel involved in the above procedures should be adequately trained in safety procedures,
including the use, limitations and maintenance of protective equipment. Caution must be
exercised so that occupants of the building and others in the vicinity are not put at risk by any
procedures undertaken or by the handling of chemicals.
7.2 WATER TESTING
Sampling for Legionella and the interpretation of results are specialised processes.
Further
advice should be sought before sampling is done. Since Legionella is widespread in nature,
sampling often yields positive results. Many water systems are colonised with Legionella
however, without being associated with infections. The dose of Legionella required to infect
persons, the variation between individuals and the pathogenicity of the different strains are not
fully understood, so it is difficult to determine the risk solely on the basis of water sampling
results. For these reasons, routine water sampling for Legionella is not advocated but sampling
may sometimes be appropriate to check the efficacy of the water treatment regime.
Currently, the analysis of water for the presence of Legionella takes seven to ten days, so that
implementation of any corrective measures, based on culture results, would obviously be
delayed.
Any decision to sample should not divert resources from precautionary measures, and negative
results should not lead to complacency or a relaxation of standards.
Cooling towers and associated water systems should be subject to routine monitoring as part of
the water treatment program designed to control scaling, corrosion and fouling. Monitoring of
pH, total dissolved solids and/or conductivity, bacterial counts and disinfectant or biocide
concentration will indicate when the water treatment program requires modification and the point
at which thorough cleaning and disinfection are necessary.
Further information on water testing can be obtained from AS/NZS 3666 Air handling and
water systems of buildings – Microbial control Part 3: Performance-based maintenance of
cooling water systems.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
8. POTTING MIX
Persons should take precautionary steps to prevent Legionella infection from potting mix and
other compost materials. The following special precautions should be taken:
•
•
•
•
open potting mix bags with care to avoid inhaling airborne potting mix;
moisten the contents of the bag on opening – make a small opening and insert a garden
hose to dampen the potting mix;
wear gloves to avoid transferring potting mix from hand to mouth; and
always wash hands after handling potting mix, even if gloves have been worn.
The same precautions should be taken when handling soil, peat, mulch and garden composts.
9. RELEVANT LEGISLATION
9.1 OCCUPATIONAL SAFETY AND HEALTH ACT 1984
This Act covers all workplaces except those covered by mining and petroleum legislation and
those in which Commonwealth employees work.
Employers, under Section 19(1), have a duty to provide and maintain a working environment in
which employees are not exposed to hazards and to ensure the safety and health of others who
may be affected by the work that is being done. Employers must inform and train employees, as
is necessary, to enable them to perform their work safely.
Under Section 21, employers and self-employed persons also have a duty to take reasonable care
to ensure their own safety and health at work.
In addition, an employer should ensure that the use, handling, cleaning, maintenance,
transportation and disposal of plant and substances at the workplace is carried out in such a
manner that employees are not exposed to hazards.
Employees, under Section 20, also have a duty to take reasonable care to ensure their own safety
and health and that of others in the workplace. Employees must also comply with instructions
and use protective clothing and equipment provided by their employers in the interests of safety
and health.
Regulation 3.38 of the Occupational Safety and Health Regulations 1996 requires employers
to consider the measures to be taken to control the level of any gases, vapours, dust or other
airborne contaminants so that the safety and health of employees is not at risk.
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Under Regulation 2.5 of the Occupational Safety and Health Regulations 1996, an employer
must notify the WorkSafe Western Australia Commissioner of details where an employee is
affected by Legionnaires’ Disease.
9.2 HEALTH ACT 1911
Under Section 3(1) of the Health Act 1911, Legionella infection (including Legionnaires’
Disease and all other Legionelloses) is prescribed as a notifiable infectious disease. Section
276(1) requires a medical practitioner, on the day of diagnosis of such a disease, to inform the
Health Department of Western Australia. The Health Department will then inform the local
government authority and the occupier of premises with which the patient has had contact in the
last 2-10 days (both homes and workplaces where applicable).
The Communicable Diseases Unit of the Health Department of Western Australia advises
WorkSafe Western Australia of all reported cases of Legionnaires’ Disease which can be traced
to workplaces.
The Health (Air-Handling and Water Systems) Regulations 1994 have effect throughout
Western Australia and apply to all buildings classified by the Building Code of Australia with the
exception of classes, 1, 2 and 10 (ie. domestic residences and non-habitable out-buildings). The
Regulations apply to the operation and maintenance of air-handling and water systems and
cooling towers whether installed before or after the gazettal date. Provisions applying to the
design and installation of such systems are not, however, retrospective. The Regulations adopt
Australian Standard AS 3666, Air-handling and water systems in buildings – Microbial control,
Parts 1 and 2, and must be read in conjunction with this standard.
The Health (Garden Soil) Regulations 1998 declare garden soil to be a hazardous substance
(Regulation 5) and requiring Schedule 1 warning notice to be displayed on packaging or at point
of sale for unpackaged garden soil. Persons dealing with potting mix or other compost materials
should be familiar with the provisions of the Regulations.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
10.
MINIMUM MAINTENANCE
Below is a chart outlining a minimum maintenance plan.
Inspection
Regular Cleaning
Type of Disinfection
At least
monthly.
Drained, cleaned
and flushed as
necessary.
Biocide eg.
chlorination.
Keep dry when not
in use.
AIR-HANDLING
SYSTEMS
INCLUDING
STAND-BY
INSTALLATIONS
At least
monthly.
Drained, cleaned
and flushed as
necessary.
Household bleach.
Keep dry when
not in use.
EVAPORATIVE
COOLERS
At least every
three months.
Every three
months.
Household bleach.
Keep dry when not in
use.
SPAS
Regularly.
Replace at least 10%
of water weekly.
Chlorine or bromide.
Keep dry when not in
use.
HUMIDIFIERS
Monthly.
When necessary.
Soapy water.
Keep dry when not in use.
At least annually.
Monthly for water
treatment units.
Cleaned and flushed
at least annually.
Monthly for water
treatment units.
Other-wise at least
annually.
Cleaned and flushed
monthly when necessary.
Weekly for irregularly used
shower heads/taps.
Chlorination or heat
disinfection.
At least annually.
Cleaned and flushed initially
annually, then as necessary.
Chlorination.
COOLING TOWERS
AND ASSOCIATED
EQUIPMENT
INCLUDING
STAND-BY
INSTALLATIONS
WATER SYSTEMS
INCLUDING STANDBY INSTALLATIONS
HOT
WARM
COLD
20
Maintain hot water
temperature.
Flush outlets with hot water.
CODE OF PRACTICE LEGIONNAIRES DISEASE
11.
REFERENCES
Occupational Safety and Health Act 1984.
Health Act 1911.
Health (Air-Handling and Water Systems) Regulations 1994.
Health (Garden Soil) Regulations 1998.
AS/NZS 3666:1995, Air-handling and water systems of buildings – Microbial control, Part 1:
Design, installation and commissioning.
AS/NZS 3666:1995, Air-handling and water systems of buildings – Microbial control, Part 2:
Operation and maintenance.
AS/NZS 3666:2000 Air handling and water systems of buildings – Microbial control Part 3:
Performance-based maintenance of cooling water systems.
AS 3500, National Plumbing and Drainage Code, Part 4-1994, Hot water supply systems.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
APPENDIX:
GENERAL PRINCIPLES FOR MANAGING
OCCUPATIONAL SAFETY AND HEALTH IN
WORKPLACES
1.1 LEGISLATIVE FRAMEWORK IN WESTERN AUSTRALIA
The Occupational Safety and Health Act 1984 sets objectives to promote and improve
occupational safety and health standards. The Act sets out broad duties and is supported by more
detailed requirements in the Occupational Safety and Health Regulations 1996. The legislation
is further supported by guidance material such as approved codes of practice. This legislative
framework is depicted below.
Major provisions:
OCCUPATIONAL
SAFETY AND
HEALTH ACT
\
•
•
•
•
•
The General Duties
Resolution of Issues
Safety and Health Representatives
Safety and Health Committees
Enforcement of Act and Regulations
supported by
OCCUPATIONAL
SAFETY &
HEALTH
REGULATIONS
\
The Occupational Safety and Health Regulations 1996 set
minimum requirements for specific hazards and work practices,
including reference to National Standards developed by the
National Occupational Health and Safety Commission and
Australian Standards developed by Standards Australia
and
•
GUIDANCE
MATERIAL
\
•
•
•
Codes of Practice approved for Western Australia in
accordance with Section 57 of the Act
Guidance Notes developed by the WorkSafe Western
Australia Commission
National Codes of Practice and National Standards
developed by the National Occupational Health and Safety
Commission
Australian Standards developed by Standards Australia
1.2 ACCESS TO ACT, REGULATIONS AND OTHER RELEVANT
DOCUMENTS
Employers are required to provide information to employees, to alert them to areas where
hazards may exist and to improve their understanding of safe work practices. The Regulations
specify documents which must be made available for perusal by employees at the workplace.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
Persons at workplaces to have access to Act etc.
Regulation 3.2 states
A person who, at a workplace, is an employer or the main contractor must ensure that, as soon as
practicable following a request from a person who works at the workplace, there is available for
that person’s perusal an up to date copy of —
(a)
the Act;
(b)
these regulations;
(c)
all Australian Standards, Australian/New Zealand Standards and NOHSC documents
or parts of those Standards or documents referred to in these regulations that apply
to that workplace;
(d)
all codes of practice approved under section 57 of the Act that apply to that
workplace; and
(e)
guidelines or forms of guidance referred to in section 14 of the Act —
(i)
the titles of which have been published in the Government Gazette and
which are set out in Schedule 3.1; and
(ii)
which apply to that workplace.
1.3 THE GENERAL DUTIES - AN OVERVIEW
The Act contains general duties which describe the responsibilities of people who affect safety
and health at work. Employers must, so far as is practicable,
•
•
•
•
•
provide a workplace and safe system of work so that, as far as practicable, employees are
not exposed to hazards;
provide employees with information, instruction, training and supervision to allow them
to work in a safe manner;
consult and co-operate with safety and health representatives in matters related to safety
and health at work;
provide adequate protective clothing and equipment where hazards cannot be eliminated;
and
ensure plant is installed or erected so it can be used safely.
Employees must take reasonable care to ensure their own safety and health at work and the safety
and health of others affected by their work.
Self-employed persons also must take reasonable care to ensure their own safety and health at
work and, as far as practicable, ensure the work does not affect the safety and health of others.
Designers, manufacturers, importers and suppliers of plant must ensure the plant is safe to install,
maintain and use at workplaces. Safety and health information must be supplied with all plant and
substances used at work.
Designers and builders of a building or structure for use as a workplace must ensure, so far as is
practicable, that persons constructing, maintaining, repairing, servicing or using the building or
structure are not exposed to hazards.
The WorkSafe Western Australia Commission guidance note The General Duty of Care in
Western Australian Workplaces provides detailed information on the ‘duty of care’. The
guidance note can be purchased from WorkSafe Western Australia, Westcentre, 1260 Hay
Street, West Perth [Tel. (08) 9327 8777] or is available via the Internet Service on Safetyline
[www.safetyline.wa.gov.au].
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1.4 HAZARD IDENTIFICATION, RISK ASSESSMENT AND RISK CONTROL
The Act: Section 19 states (in part)
(1)
An employer shall, so far as is practicable, provide and maintain a working environment in
which his employees are not exposed to hazards and in particular, but without limiting the
generality of the foregoing, an employer shall —
(a)
provide and maintain workplaces, plant, and systems of work such that, so far as is
practicable, his employees are not exposed to hazards.
Under Section 19(1)(a) of the Occupational Safety and Health Act, employers have a duty to
ensure, as far as practicable, that employees are not exposed to hazards at the workplace. The
Regulations require employers to identify hazards, and assess and control risks.
Identification of hazards, and assessing and addressing risks, at workplaces
Regulation 3.1 states
A person who, at a workplace, is an employer, the main contractor, a self-employed person, a
person having control of the workplace or a person having control of access to the workplace
must, as far as practicable —
(a)
identify each hazard to which a person at the workplace is likely to be exposed;
(b)
assess the risk of injury or harm to a person resulting from each hazard, if any,
identified under paragraph (a); and
(c)
consider the means by which the risk may be reduced.
The regulation outlines three basic steps:
•
Identification of hazards
This involves recognising things which may cause injury or harm to the health of a person,
for instance flammable material, ignition sources or unguarded machinery.
•
Assessing risk
This involves looking at the possibility of injury or harm occurring to a person if exposed
to a hazard.
•
Controlling the risk of injury or harm
This involves introducing measures to eliminate or reduce the risk of a person being
injured or harmed.
It is important to regularly review the steps, especially if there are changes in the work
environment, new technology is introduced, or standards are changed.
Employers should consult with safety and health representatives, if any, and employees during
these steps.
1.4.1
Identifying hazards
There are a number of ways of identifying potential sources of injury or disease.
Selection of
the appropriate procedure will depend on the type of work processes and hazards involved.
Procedures may range from a simple checklist for a specific piece of equipment or substance to
a more open-ended appraisal of a group of related work processes. A combination of methods
may provide the most effective results.
Methods of identifying workplace hazards include:
•
developing a hazard checklist;
•
conducting walk-through surveys;
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•
•
•
•
•
•
reviewing information from designers or manufacturers;
analysing unsafe incidents, accident and injury data;
analysing work processes;
consulting with employees;
examining and considering material safety data sheets and product labels; and
seeking advice from specialist practitioners and representatives.
A hazard means anything that may result in injury or harm
to the health of a person.
Some hazards such as mechanical hazards, noise, or the toxic properties of substances are
inherent in the work process. Other hazards result from equipment or machine failures and
misuse, control or power system failures, chemical spills, and structural failures.
Table 1 below lists some types of hazards together with some specific examples.
HAZARD
EXAMPLES
OUTCOMES
(examples of injury or harm)
Manual handling
over exertion/repetitive movement
sprains, strains, fractures
Falls
falling objects, falls, slips and trips of
people
fractures, bruises, lacerations,
dislocations, concussion, permanent or
fatal injuries
Electricity
electrical current, lightning
shock, burns, electrocution
Machinery
and equipment
being hit, hitting objects, being caught
in or between, over-turning vehicles
cuts, bruises, dislocations, fractures,
amputation, permanent or fatal injuries
Hazardous
substances
chemicals such as acids, hydrocarbons,
heavy metals
toxic effects, dermatitis, respiratory
illnesses, cancers
Extremes of
temperature
effects of heat or cold
burns, frost bite, heat stress,
heat stroke
Noise
excessive noise
permanent hearing damage
Radiation
ultra violet, welding arc flashes,
micro waves, lasers
burns, cancers, damaged eye sight,
blindness
Biological
viruses, bacteria, fungi, toxins
Hepatitis, Legionnaires’ Disease,
Q Fever, tetanus, HIV/AIDS, allergies
Vibration
hands and whole of body
organ, nerve and muscle damage
Psychological stress
intimidation, organisational change,
violence, conflict, time pressure
high blood pressure, headaches and
migraine, anxiety, depression,
absenteeism
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CODE OF PRACTICE LEGIONNAIRES DISEASE
1.4.2
Analysing and assessing risks
Risk, in relation to any injury or harm, means the probability of
that injury or harm occurring.
Risk assessment of the hazards identified in the first step should result in a list of potential
injuries or harm and the likelihood of these occurring. The potential for fatal injury should be
considered for each identified hazard. If hazards are listed they should be in the order of the
most to the least serious, eg. from fatal to minor injury.
In assessing risks, consideration should be given to the state of knowledge about the frequency of
injury or disease, the duration of exposure to injury or disease sources and the likely severity of
the outcomes.
Knowledge gained from similar workplaces or similar processes may be relevant to this risk
assessment. Items to be considered include:
•
•
•
frequency of injury - how often is the hazard likely to result in an injury or disease?
duration of exposure - how long is the employee exposed to the hazard?
outcome - what are the consequences or potential severity of injury?
Assessing these three factors will indicate the probability or likelihood of injury or harm
occurring to workers involved in a particular work process. It also indicates the likely severity of
this harm.
Risk assessment requires good judgement and awareness of the potential risks of a work process.
Any person undertaking the risk assessment must have knowledge and experience of the work
process. Risk assessment will be more complicated or difficult if the data or information
regarding hazards of a work process is incomplete.
In some cases it may be necessary to break down the activity or process into a series of parts and
assess each part separately.
Risk
•
•
•
•
•
•
•
•
•
assessment should include:
assessing the adequacy of training or knowledge required to work safely;
looking at the way the jobs are performed;
looking at the way work is organised;
determining the size and layout of the workplace;
assessing the number and movement of all people on the site;
determining the type of operation to be performed;
determining the type of machinery and plant to be used;
examining procedures for an emergency (eg. accident, fire and rescue); and
looking at the storage and handling of all materials and substances.
This step should provide information where and which employees are likely to be at risk of
incurring injury or disease, how often this is likely to occur, and the potential severity of that
injury or disease risk.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
1.4.3
Identifying control measures
The final step in risk assessment is to determine the control measures that need to be taken and
the ongoing review of those measures. There is a hierarchy or preferred order of control
measures ranging from the most effective to the least effective. The preferred order is outlined
in the table below.
The control of occupational injury and disease risks should preferably be dealt with by design,
substitution, redesign, separation or administration. These controls generally eliminate, reduce
or minimise risk in a more reliable manner than personal protective equipment.
Controls involve implementing measures which reduce the hazard and risk in the workplace.
Where regulations require specific methods to control the risk, these must be complied with.
TABLE 2 - Hierarchy or preferred order of control
elimination
removing the hazard or hazardous work practice from the workplace.
This is the most effective control measure;
substitution
substituting or replacing a hazard or hazardous work practice with a less
hazardous one;
isolation
isolating or separating the hazard or hazardous work practice from people involved
in the work or people in the general work areas from the hazard. This can be done
by installing screens or barriers or marking off hazardous areas;
engineering
if the hazard cannot be eliminated, substituted or isolated, an engineering control
control
is the next preferred measure. This may include modifications to tools or
equipment, or providing guarding to machinery or equipment;
administrative
includes introducing work practices that reduce the risk. This could include
control
limiting the amount of time a person is exposed to a particular hazard; and
personal
should be considered only when other control measures are not practicable or
protective
to increase protection.
equipment
Control measures are not mutually exclusive. That is, there may be circumstances where
more than one control measure should be used to reduce exposure to hazards.
In some instances, a combination of control measures may be appropriate. Control measures
should be designed:
•
to eliminate or reduce the risks of a hazardous work process and to minimise the effects
of injury or disease; and
•
to reduce the risk of exposure to a hazardous substance.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
1.4.4
Control through personal protective equipment
Personal protective equipment should be a last resort only, and be used in circumstances where
other methods of control are not practicable. The factors which determine the appropriateness
of using personal protective equipment include:
•
the nature of the work or the work process concerned;
•
the severity of any potential injury or disease;
•
the state of knowledge about the injury or disease related to the work or process; and
•
information available to employers about methods of preventing injury or disease
associated with a particular hazard or risk.
There are some situations where temporary use of personal protective equipment may be
necessary. These include:
•
where it is not technically feasible to achieve adequate control of the hazard by other
measures. In these cases, the hazard should be reduced as far as practicable by other
measures and then, in addition, suitable personal protective equipment should be used to
secure adequate control;
•
where a new or revised risk assessment indicates that personal protective equipment is
necessary to safeguard safety and health until such time as adequate control is achieved by
other methods, for example, where urgent action is required because of plant failure; and
•
during routine maintenance operations. Although exposure to hazards occurs regularly
during such work, the infrequency and small number of people involved may make other
control measures impracticable.
1.4.5
Review of control measures
Constantly reviewing control measures is important to ensure they continue to prevent or
control exposure to hazards or hazardous work practices.
Engineering controls should be regularly tested to ensure their effectiveness. Performance
testing and evaluation standards should be established.
Repair and maintenance programs should specify:
•
where servicing is required;
•
the extent of servicing required;
•
the nature of the servicing required;
•
the frequency of servicing;
•
who is responsible for maintaining repair and maintenance programs; and
•
how defects will be corrected.
In order to keep accurate records, a recording or reporting system should be developed,
implemented and maintained.
1.5 THE MEANING OF PRACTICABLE
Some of the general duty provisions in the Act and some requirements in the Regulations are
qualified by the words “so far as is practicable”.
“Practicability” applies to general duties for employers, self-employed people, people with
control of workplaces, designers, manufacturers, importers, suppliers, erectors and installers,
and to certain requirements in the Regulations.
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CODE OF PRACTICE LEGIONNAIRES DISEASE
These people are expected to take practicable and reasonable measures to comply with the
requirements.
If something is practicable, it is capable of being done. Whether it is also reasonable takes into
account:
•
the severity of any injury or harm to health that may occur;
•
the degree of risk (or likelihood) of that injury or harm occurring;
•
how much is known about the hazard and the ways of reducing, eliminating or controlling
it; and
•
the availability, suitability and cost of the safeguards.
The risk and severity of injury must be weighed up against the overall cost and feasibility of the
safeguards needed to remove the risk.
Common practice and knowledge throughout the relevant industry are taken into account when
judging whether a safeguard is “reasonably practicable”. Individual employers could not claim
that they did not know what to do about certain hazards if those hazards are widely known by
others in the same industry, and safeguards were available.
The cost of putting safeguards in place is measured against the consequences of failing to do so.
It is not a measure of whether the employer can afford to put the necessary safeguards in place.
While cost is a factor, it is not an excuse for failing to provide appropriate safeguards,
particularly where there is risk of serious, or frequent but less severe, injury.
Where a regulation exists and is not qualified by the words “as far as is practicable”, the
regulation must be complied with as a minimum requirement.
The WorkSafe Western Australia Commission guidance note The General Duty of Care in
Western Australian Workplaces provides detailed information on the ‘duty of care’. The
guidance note can be purchased from WorkSafe Western Australia, Westcentre, 1260 Hay Street,
West Perth [Tel. (08) 9327 8777] or is available via the Internet Service on Safetyline
[www.safetyline.wa.gov.au].
29