By Adem Lewis / in , , , , , , /


♪ (Music Playing) ♪ Hello, and welcome to this
virtual seminar series presentation on workplace
exposure standards and how to use
them. I’m Michael Young, the Safe Work Australia
Member for the ACT. I’ll begin by acknowledging
the traditional custodians of the land on which we
meet, the Ngunnawal people. I acknowledge and respect
their continuing culture and the contribution they
make to this city and region. Today’s seminar will
provide practical information on how
workplace exposure standards should be used
to protect the health of workers and to comply with
regulatory requirements. Our speaker is Ms
Linda Apthorpe. Linda is a certified
occupational hygienist, a fellow of the Australian Institute
of Occupational Hygienists, and a representative
on the Australian Institute of Occupational
Hygienists Council. She has a master of
science in occupational hygiene practice, and is
a consultant occupational hygienist and lecturer at
the University of Wollongong. Linda has over 20 years
of experience carrying out risk and exposure
assessments in the mining, construction,
manufacturing, pharmaceutical, medical and
agricultural industries. Her expertise includes the
analysis, evaluation and control of workplace
hazards, such as asbestos, dust, quartz, noise
and pesticides. Please join me in
welcoming Linda. (Applause) Well thank you very much
for that introduction, and also the invitation
to be here today. I’m here on behalf of the
Australian Institute of Occupational Hygienists,
and our overall objective is to use science and
engineering to promote and to protect worker health
and prevent illness. Thank you also for joining
me here today to learn about the exposure
standards and in this presentation which has
been prepared by the AIOH Exposure
Standards Committee. There we go, that’s
what the title is, and we get
straight into it. In this short presentation
on the workplace exposure standards, it’s
about improving the knowledge of workplace exposure
standards or the WES for health and safety
professionals. In particular what they are,
why you use them and how they can be utilised in
various ways to protect worker health, and that’s
by minimising the risk of exposure to a variety
of workplace hazards. The exposure standards can
be used for determining the degree of exposure, in
monitoring programs to minimise risk and any
potential health effects, to determine compliance
and ultimately be used to protect worker health
and to prevent illness. In many industrial processes
such as manufacturing, mining, construction
and service industries, workers can be exposed
to a range of various chemicals and
dusts, physical agents such as noise and heat, and
biological agents such as mould spores or bacteria,
all of which can be emitted from the workplace
processes. Now these agents have various
toxicological effects which can be mainly dose
dependent, and that means the more time you are exposed
and the higher the level, then the more chance
you have of developing an adverse health effect. So to limit this
risk and reduce the risk, exposure standards are set
for a wide range of many commonly used
chemicals and agents. The exposure standards
are a scientifically determined level, which
there should be no adverse health effects or cause
any undue discomfort to nearly all workers.
Sometimes they’re also known as the occupational
exposure limits. Workplace exposure standards
exist for a variety of hazardous workplace chemicals
and various hazards. They’re typically broken
into chemical hazards such as dusts and solvents, and
physical hazards such as noise, heat stress
and radiation. Today we’re only discussing
the risk of exposure to chemical hazards such
as vapours, fumes, gases and dusts, and these are
all airborne contaminants which we can inhale
into our lungs. Our national exposure
standards have been set by Safe Work Australia,
and there are around 700 exposure standards which
can be found online at the Hazardous Chemical
Information System, HCIS. They’re available on the
Safe Work Australia website. Supplementary information
is also available on the HCIS website regarding
interpretation and further guidance and definitions
of the exposure standards. In addition, there may be
special standards, codes of practice or
guidance material which can be specific to
some industries. Professional bodies such
as AIOH and some overseas organisations also provide
guidance and exposure standard information which can be used
to protect worker health. The exposure standards are
defined as the airborne concentration of a
particular substance or mixture that must not be
exceeded, and there are three forms of the exposure
standard depending on the type of effect or mechanism
it has on the human body. The first one is the eight
hour exposure standard, the TWA, and that’s
the concentration of a substance calculated over
an eight hour day over a five day working week. This standard is set to
protect workers from long term or chronic health
effects, for example exposure to crystalline
silica or lead, and that from a long period of time
these exposures can have a cumulative effect. The short term exposure
limit, or STEL, is the average concentration
of a substance which is calculated over a
15 minute period. Now there are some special
rules about the STEL in that it cannot be exceeded or repeated
more than four times without at least one hour in
between each exposure event. This type of standard is
used to protect workers from short term health
effects from substances which can cause irritation
or narcosis such as solvents. The last one is the peak
limitation, and it’s the maximum concentration which
cannot be exceeded at any time. This type of standard is
set to protect workers from rapidly acting substances
such as hydrogen cyanide. Not every agent has these
types of exposure standards, and the occupational
hygienist will check which one is appropriate for the
particular workplace scenario. So why do we actually need
the exposure standards and why do we need to use them? They’re really important
in the risk assessment and management of risks
within the workplace. Excess levels of airborne
contaminants in the workplace may lead to toxic
effects such as respiratory diseases of asthma or
maybe even silicosis. It can lead to
cardiovascular diseases, simple narcosis or even
occupational cancers such as bladder cancer
or leukaemia. By understanding a
worker’s level of exposure, then we can compare this
information to determine the significance of
exposure and the level of risk to that
particular worker. We can also assess if
health monitoring is required in order to
prevent illness developing with the aim to reverse
any health effects. There’s more information
in the regulations from Safe Work Australia about
which substances require health monitoring and when it
does need to be carried out. For compliance purposes with
the WHS or OH&S legislation, employees must not let their
workers be exposed above the exposure standards.
In fact exposures need to be kept as low as
reasonably practicable. And finally, workers may
have a concern about a particular exposure or
a particular chemical in their workplace, and
therefore measurement may be required to ensure they
are not being exposed or put in place various
control strategies to minimise that exposure. Safe Work Australia
also provides additional information about various
chemical hazards, which is important when working with
the exposure standards. These are categorised
according to the GHS, the Globally Harmonised
System for chemicals. So where chemicals
are noted as being carcinogenic, cause skin
irritation or even could be absorbed by the skin, or
they may be a sensitiser chemical which can
cause diseases such as occupational asthma, it’s
really important that OH&S personnel and occupational
hygienists consider the implication of exposure to
these chemical hazards and to work to reduce exposures
and control them as much as possible for any person
who has to work or handle these particular chemicals. It’s important to remember
that the exposure standards have certain limitations. They’re not fine lines
between safe or unsafe in terms of working
environments, as a small number of workers may be
affected at levels below the exposure standards. Therefore airborne
exposures must always be kept as low as
reasonably practicable. The standards are not the
same as road speed limits where you can drive right
up to the limit or perhaps even fudge a
little bit over. So to protect worker health,
exposures should always be kept to at least half
of the exposure standard, and this is sometimes
known as the action level. This helps to drive good
practice and also can be used to implement various
control strategies. The exposure standards
are designed for use in the occupational environment
only, and are not applicable for use in the
wider community as there are elderly and children
present in that environment. Although some chemicals have
a risk phrase for the skin, it’s not taken into
account when setting the airborne exposure
standards. In this case biological
monitoring may be more appropriate to assess the
total body burden from exposure via inhalation
and skin absorption. When evaluating
exposure, we need to know what, why, how and when. So prior to conducting
any sampling, an exposure assessment program needs to
be developed by doing some research into the specific
chemical to measure and to ensure the valid test method
for a capture and analysis is used to measure that
worker’s airborne concentration. Also we can use the results
of personal sampling to compare against the
exposure standards. Now here we can see this
air sampling equipment being placed on to this
worker who’s going to wear it for their whole
eight hour shift. And this is the type
of sampling that an occupational hygienist
will be able to do for you. So here is an example of
what a worker’s exposure looks like over a
typical eight hour day. The airborne concentration
of this chemical substance usually varies throughout
their shift due to various factors such as intermittent
or various work tasks, and the quantity of chemical
used throughout the day. This graph shows the
variability of those airborne exposures that a
worker can experience over the whole eight hour day
for a specific chemical. In this instance the
worker’s exposure is averaged over the whole
day, is the time weighted average of 27
parts per million. But the highest peak can be
seen, which is the exposure measured over a specific
task, and that was measured at 50 parts per million. Now these measured values
can then be compared against the relevant
exposure standard for that specific chemical. In this case the TWA
exposure standard is in fact 30 parts per million. Remember the exposure
standards are not hard and fast rules of satisfactory
or unsatisfactory, so because the result here
of 27 is very close to 30 parts per million,
the exposure is actually too high and various controls
would need to be used in order to reduce that
exposure to at least half of the exposure
standard value. However if this worker
is working a shift that’s longer than eight hours,
then the exposure standard may need to be adjusted
because there is less time for recovery and for the
substance to be eliminated from the body before the
worker fronts up to work for another daily dose. So the occupational
hygienist will calculate an adjustment which is
suitable for that specific substance using a
standard method. In many cases the new
adjusted value will be less than the TWA exposure
standard, and therefore controls will need to
be implemented to keep exposures down and to
reduce any health effects. To determine the exposure,
we must also plan the number of samples to
take and who we are going to do the sampling on. The hygienist will need
to take more than just one sample on one
worker on one day. Also we’re going to need to
include groups of workers who do the same task or different
tasks in the workplace, and these are known as similar
exposure groups or SEGs. In order to carry out that
representative sampling, a statistically valid
sampling program takes into account all of the
workplace activities, the workers who are doing the
actual tasks and the SEGs as part of a robust
risk assessment. So it’s definitely going to
mean more than just one sample, and to design that
sampling program of course you’re going to need to engage
an occupational hygienist. To make an assessment of
a worker’s exposure, we really need to do it properly
because it’s really important. To estimate that exposure,
we need to do various measurements where the
sampling equipment is placed on to the worker, and that’s
going to sample the air they’re going to be breathing
in during their work shift. And this is the personal
sampling, and only the results of personal
sampling can be used to compare against the
exposure standard. Now in this diagram we can
see the breathing zone of the worker where the
sampler needs to be placed. We also want to do the
sampling during a worker’s normal work activities, or
when we want to find out about exposures during
abnormal work activities like cleaning or
maintenance tasks. The majority of sampling
in workplaces is personal, however sometimes static
sampling or fixed location samples can also be used
to determine the source of contaminants in
the workplace. It’s important to remember
that the results of any static sampling cannot be
compared to the exposure standards and must
never be used to make a determination of a
worker’s exposure. The exposure standards
are the basic tools which occupational hygienists
use to assess the degree of risk from
chemical exposure. They can also be used
to design and implement various control strategies. Therefore the results of
personal sampling will be used to compare against
the exposure standards. We may also have
to consider various adjustments due to the
worker’s shift length. Occupational hygienists
use the sampling results and our workplace
observations to assess the risks to health
and apply controls. Remember we want to
keep exposures as low as reasonably practicable. During that whole process
it’s also important to involve the workers and
management, as ultimately success in reducing
exposures involves everyone within the workplace. So
our results and reports will be communicated
back to the workplace. So once the controls are
implemented, we may also need to re-evaluate where
necessary, and to ensure that our control strategies
have been effective. So here’s some key
messages to take away. Remember any workplace
sampling and analysis must be conducted properly using
the correct methods and analytical techniques, and
to use trained, experienced and competent practitioners
in the process. A comprehensive monitoring
program will determine the range and extent of
workplace exposures for comparison against the
exposure standards. It’s the cornerstone of
occupational hygiene, risk assessment and
management of risks within the workplace. It’s also important to
consider the component of control of occupational
disease and setting of policies on
occupational health. And that exposure data should
also be statistically analysed to determine compliance,
and also be used to help with control strategies
required to reduce exposures. Thank you very much. (Applause) On behalf of Safe Work
Australia, I’d like to thank you for that
presentation and to congratulate you for making
what is traditionally a very complex subject so
clear and accessible. So thank you once again. ♪ (Music Playing) ♪


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