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Linda Apthorpe from the Australian Institute of Occupational Hygienists (AIOH) discusses how best to use workplace exposure standards to protect workers from exposure to airborne contaminants. 

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About this seminar

Workplace exposure standards are an essential component in minimising occupational disease through their use in workplace risk mitigation programs. They assist in minimising the risk of adverse health effects by establishing measurable limits for businesses to aim below, and are legally enforceable in all jurisdictions in Australia.

This video provides guidance on interpreting and applying workplace personal air monitoring data against exposure standards to meet compliance targets and more importantly, to protect worker health.

Who is this seminar for?

This seminar is useful for occupational hygienists, regulators, industry and worker representatives, and work health and safety advisors. It is particularly relevant for people working in the manufacturing, mining and construction industries that may result in exposure to airborne contaminants.

About the presenters

Linda Apthorpe is a Certified Occupational Hygienist (COH), Fellow and Council Member of the Australian Institute of Occupational Hygienists (AIOH). She has a Masters of Science in Occupational Hygiene Practice from the University of Wollongong. Linda is a consultant occupational hygienist and lecturer at the University of Wollongong with over 20 years of experience conducting risk and exposure assessments in the mining, construction, manufacturing, pharmaceutical, medical and agricultural industries.

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Transcript

Safe Work Australia

Workplace exposure standards and how to use them

Presented on 15 November 2016

 


Presented by:

 

Michael Young, MC

ACT Government

 

Presenter:
 

Linda Apthorpe
AIOH

 


 

 

[Opening visual of slide with text saying ‘safe work australia virtual seminar series with Crest (logo)’, ‘Workplace exposure standards and how to use them, ‘Presented by Linda Apthorpe’, ‘seminars.swa.gov.au’, ‘***virtualWHS’]

[The visuals during this webinar are of each speaker presenting from lectern on stage whilst other speakers are seated, with reference to the content of a PowerPoint presentation being played on a large background screen]

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^Michael Young:^

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.

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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)#

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^Linda Apthorpe:^

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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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In this case the TWA exposure standard is in fact 30 parts per million.

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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.

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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.

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To determine the exposure, we must also plan the number of samples to take and who we are going to do the sampling on.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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)#

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^Michael Young:^

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) §#
 

[Closing visual of slide text saying ‘Brought to you by safe work Australia Virtual Seminar Series’, ‘seminars.swa.gov.au’, ***virtualWHS’]

[End of Transcript]

 


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Last modified on Wednesday 20 February 2019 [6526|88761]