Airborne Dust Exposure in Coal Mines

Airborne dust exposure in coal mines

PROTECTION AND CONTROL

August 2017 CS7153 08/17

For more information on this licence, visit https://creativecommons.org/licenses/by/4.0/.

The information contained herein is subject to change without notice. The Queensland Government shall not be liable for technical or other errors or omissions contained herein. The reader/user accepts all risks and responsibility for losses, damages, costs and other consequences resulting directly or indirectly from using this information. Protecting Queensland’s coal mine workers

The Department of Natural Resources and Mines is committed to the health and safety of all coal mine workers. We are actively working to prevent coal mine dust lung diseases, including coal workers’ pneumoconiosis and silicosis. We are also implementing stricter dust management and improvements to the respiratory component of the Coal Mine Workers’ Health Scheme to ensure the early detection of disease through efective health screening. Dust control measures in the Queensland coal mining industry continue to help protect coal mine workers from developing pneumoconiosis. This booklet aims to promote a better understanding of the health efects and control of airborne dust in coal mines.

We would like to thank Coal Services Pty Ltd (New South Wales) for allowing us to use information from their publication, Protecting against airborne dust exposure in coal mines, to develop this booklet.

Contents

1. Dust is important ...... 1 Dust size ...... 1 2. Health efects ...... 3 Coal workers’ pneumoconiosis ...... 3 Silicosis ...... 5 Scarring in the lungs ...... 6 CWP and silicosis symptoms ...... 10 Treatment ...... 12 At-risk workers ...... 14 3. Preventing dust lung diseases...... 15 Specifed dust exposure limits ...... 15 Hazards in longwall coal mines ...... 15 Hazards in open-cut coal mines ...... 16 Exposure to respirable silica dust ...... 17 Health assessments ...... 18 4. Controlling dust exposure ...... 20 Dust control methods ...... 20 Measuring dust levels ...... 23 Personal dust monitoring ...... 24 Determining respirable dust concentrations ...... 25 Determining inhalable dust concentrations ...... 26 Respiratory protective equipment ...... 28 Other control measures ...... 28 More information ...... 29 1 DUST IS IMPORTANT 1. Dust is important

Dust is a word often used to describe the fne, dry particles of dirt and waste on the ground and in the air. In coal mines, dust particles can be much fner than the body will normally encounter elsewhere. The machinery used for mining creates coal and crystalline silica dust particles so small they cannot be seen by the naked eye. Prolonged exposure to high concentrations of these fne particles can lead to a range of serious lung diseases, such as silicosis, coal workers’ pneumoconiosis, chronic obstructive pulmonary disease and lung cancer.

Dust size Dust particles fall into two categories, according to their size: • inhalable dust (approx. 0.1 mm diameter) • respirable dust (approx. 0.005 mm diameter). To give you an idea of these sizes, the following diagram compares both types of dust with the diameter of a single human hair.

1 Dust particle size comparison

Human hair Inhalable dust Respirable dust 0.089 mm 0.1 mm 0.005 mm

Inhalable dust Respirable dust

Size Dust particles of Smallest dust all sizes (typically particles (typically less than 0.1 mm less than 0.005 mm diameter) diameter)

Visibility Can be seen with Cannot be seen with the naked eye the naked eye

The size of a dust particle determines how far it can travel in the lungs. Due to their small size, respirable dust particles can travel into the lowest parts of the lungs.

2 2 HEALTH EFFECTS 2. Health efects

Exposure to respirable coal dust and respirable crystalline silica dust over an extended period of time can lead to the development of a dust-related lung disease. Pneumoconioses are progressive diseases, which means they can worsen over time. The longer a person is exposed to high concentrations of respirable dust, the more the disease can progress.

Coal workers’ pneumoconiosis Coal workers’ pneumoconiosis (CWP), or black lung disease, is caused by long-term exposure to high concentrations of respirable coal dust. The disease may take several years to develop— commonly 10 years or more. The disease gets its name because afected lungs appear to be black in colour rather than their normal healthy pink.

3 The body reacts to the dust particles by forming layers of scar tissue over the afected area. The collections of dust and scarring may later show up as small, round nodular shapes on a chest X-ray. CWP is categorised as either simple CWPor complicated CWP (also called progressive massive f brosis). Simple CWP is characterised by nodules of scar tissue that are less than 10 mm in diameter. There are usually no symptoms to indicate a person has simple CWP. With continued exposure to high concentrations of respirable dust, simple CWP will eventually progress to complicated CWP. A person with complicated CWP develops nodules of scar tissue that are greater than 10 mm in diameter. There are a range of symptoms, from increasing breathlessness to eventual respiratory failure.

4 Silicosis Silicosis is a lung disease similar to CWP. It is caused by prolonged exposure to respirable crystalline silica dust. The most abundant form of silica is quartz—the terms are often used interchangeably. Respirable silica dust can cause fbrous or scar tissue to form in the lungs (silica-induced pneumoconiosis) that reduces the lungs’ ability to extract oxygen from the air. Like CWP, silicosis has simple and complicated forms, and the symptoms are similar to those of CWP. Respirable crystalline silica dust is known to cause cancer in humans, making it more harmful to a person’s health than respirable coal dust. When inhaled, the dust particles cause a toxic chemical reaction inside the lungs.

5 Scarring in the lungs Scarring occurs in the lungs as a result of the body repeatedly trying to heal the irritated area. The following diagrams show how CWP and silicosis develop.

Note: The following images and descriptions are representative only. For professional medical advice, please consult your doctor or nominated medical adviser.

6 1 RESPIRABLE 2 ALVEOLI DUST PARTICLES

BRONCHIOLE

ALVEOLUS ALVEOLUS ALVEOLUS

Alveoli are tiny air sacs responsible for Because respirable dust particles are exchanging oxygen and carbon dioxide so small, they’re able to travel all the with the blood. A typical pair of lungs way into the alveoli, where they can contain approximately 700 million alveoli. cause irritation inside the air sac.

5 6 DENSE NODULE OF SCAR TISSUE DUST

FIBROBLASTS

FIBROUS TISSUE

ALVEOLUS ALVEOLUS ALVEOLI

If the concentration of dust is too high, Over time, with continued Fibroblast cells come to the aid of the overexposure to respirable dust, macrophages. The fbroblasts knit the process repeats many times and together, and form nodules of scar more nodules of scar tissue form. tissue around the particles. 3 4

IRRITATION MACROPHAGE DUST DUST

ALVEOLUS ALVEOLUS ALVEOLUS

In response to the dust particles, the They send out chemicals to attract lung’s defence mechanism kicks in. more macrophages and other similar Macrophages, a type of white blood types of cells. They work together to cell, engulf the dust particles to engulf and clear the dust particles. destroy or clear them away. 7 8 ALVEOLI DECREASE UNHEALTHY ALVEOLI

ALVEOLUS ALVEOLI

Overcome with scar tissue, the With continued overexposure to alveoli become unable to function respirable dust, the scarring becomes normally, reducing the transfer of so extensive that it becomes hard to oxygen into the bloodstream. breathe deeply. The amount of oxygen entering the bloodstream is reduced.

Inhalable dust Respirable dust The When breathed When breathed in, the body’s in, particles are particles can travel defence trapped in the undetected by the mouth, nose and body’s initial defence upper respiratory mechanisms (such as tract sneezing and coughing) Concentrated The smallest particles amounts can are able to reach deepest cause airways parts of the lungs (the to constrict to alveoli), where they are prevent further deposited and remain dust inhalation The Particles can be The particles cause body’s expelled by the irritation, which the body response body through attempts to heal—this coughing and causes scar tissue to form sneezing, and around each dust particle by producing (healthy tissue is replaced mucous and by fbrous scar tissue) sputum

9 CWP and silicosis symptoms A person with early stage CWP or silicosis may not show any symptoms. This is because dust lung diseases commonly take 10 years or more to develop. Beyond the early stages, a person may start to experience shortness of breath, wheezing and a productive (‘chesty’) cough. These symptoms may also be due to inhalable dust or smoking. If the disease progresses further it may become complicated CWP/silicosis, which is also known as progressive massive fbr osis. In this instance, the areas of fbrotic or scar tissue in the lungs is more than 1 cm in diameter. Progressive massive fbr osis can be a debilitating and life-threatening condition, and individuals may present with more severe symptoms such as increasing shortness of breath on exertion and eventually also at rest. Chest infections such as bronchitis and pneumonia may also become more frequent or chronic. The onset and severity of the disease depends on the type of respirable dust, how much dust was in the air and how long a person has been exposed to it.

Inhalable dust Respirable dust Health Most are Mucous production efects considered ‘short- increases, and shortness term’ health of breath and wheezing efects become more frequent Particles irritate Over time, chronic eyes and nose, bronchitis and other lung and may afect infections persist other health Fibrosis replaces healthy conditions such tissue until it causes as asthma and chronic obstructive bronchitis pulmonary disease and Nose may become eventual lung failure congested with dry and dusty mucous

11 Treatment There is no way to cure or reverse either CWP or silicosis. Most treatments provided are aimed at limiting further damage to the lungs, managing the symptoms and improving the person’s quality of life. Scarring of the lungs cannot be reversed. People diagnosed with CWP or silicosis should avoid further exposure to high concentrations of coal dust or silica dust. For simple cases, avoiding further exposure to harmful dust may stabilise the disease, preventing it from worsening.

12 The single biggest cause of lung diseases and related disabilities is smoking.

Smoking can contribute to the severity of dust lung diseases, so it is strongly advised that any diagnosed person stops smoking.

Preventative measures in the coal industry aim to stop CWP and silicosis occurring or, at worst, stop any progression beyond the diseases’ very early stages. Because the symptoms may remain undetected for years, periodic health surveillance medicals are critical to early detection.

13 At-risk workers Anybody exposed to harmful levels of respirable dust is at risk of developing a dust-related lung disease. A person’s risk is directly linked to their total level of exposure to dust and their personal susceptibility. Open-cut coal mine workers can be at risk during drilling and shot-fring operations in the stone overburden if not protected by proper procedures or efective cabin sealing. Underground coal mine workers are particularly at risk in mines that regularly require the extraction of stone roof and/or foor as part of their normal process. Any task that requires cutting or drilling stone containing silica has the potential to expose coal mine workers to high levels of silica dust.

14 3 PREVENTING DUST LUNG DISEASES 3. Preventing dust lung diseases

Specifed du st exposure limits In the Queensland coal mining industry, the stated dust exposure limits are outlined in the Coal Mining Safety and Health Regulation 2001.

Hazards in longwall coal mines Longwall coal mining provides one of the most difcult situations for dust control because: • longwall mining systems produce relatively high volumes of coal, which in turn can generate more respirable coal dust • workers are not protected by enclosed, air- conditioned cabins, such as those used in open-cut coal mines • there are additional dust sources such as coal crushers, powered roof support movement and beam stage loader discharge to the conveyor belt • pre-draining—a process that removes moisture content to reduce the risk of a methane gas explosion—can make coal and silica more prone to producing respirable dust.

15 High exposure to dust on longwalls can result from workers located on the return side of the shearer and/or advancing supports.

Hazards in open-cut coal mines In open-cut coal mines, workers are located in enclosed, air-conditioned cabins. Proper cabin sealing and efective, appropriate work procedures are critical to keeping exposure limits low. Controls should be applied to any task conducted outside a sealed cabin, particularly where drilling has recently occurred or is occurring (e.g. shot fring).

16 Exposure to respirable silica dust The most common types of exposure occur in, but are not limited to, the following environments. Underground coal mines: • cutting stone roof or foor, or stone bands in the seam, during continuous miner or longwall operations • roof bolting or drilling into sandstone or mudstone, or dry drilling • material transfer and loading points • ventilation returns • spraying or grouting with products that contain crystalline silica. Open-cut coal mines: • drilling or shot-fring operations, or dry drilling • any tasks that require an operator to work outside a sealed cabin, particularly in areas where fne drill tailings remain on the ground untreated.

17 Health assessments Many occupational illnesses, including CWP and silicosis, can take 10 years or more to develop, and even longer for symptoms to appear. Regular health assessments enable detection of an occupational disease in its early stages, before it has progressed and worsened. All Queensland coal mine workers participate in a mandated health scheme, which makes sure each coal mine worker is provided with a respiratory health assessment. All current and former coal mine workers should consult their doctor, or their employer’s nominated medical adviser, if they have any concerns about their health. When contacting their GP, it is important to tell their doctor that they are, or have previously been, a coal mine worker.

18 The health assessment is conducted by their employer’s nominated medical adviser. Respiratory health assessments are required: • before a person starts working as a coal mine worker • periodically, as required under the Coal Mining Safety and Health Regulation 2001, according to the worker’s individual circumstances • if the employer’s nominated medical adviser decides it is necessary.

Employers must arrange and pay for their workers’ health assessments.

For more information about the health scheme, visit www.business.qld.gov.au (search ‘coal mine health scheme’).

19 4 CONTROLLING DUST EXPOSURE

Dust control methods The risk of coal mine workers being exposed to hazardous dust particles should be managed using the hierarchy of controls shown below—with a focuson higher or der controls(elimination, substitution and isolation of the hazard) as the mostefectiv e means of treating the hazard. Hierarchy of controls

Remove the hazard Elimination Substitute a safer Substitution alternative

Separate people Isolation from the hazard

Redesign or modify Engineering Increasing efectiv eness equipment

Use training and rules Administrative to reduce risk

Provide ft-for- Personal protective equipment purpose protective equipment

20 More than one control may need to be used to adequately control the hazard. Any controls used must be maintained to ensure they continue to remain efective. Identify fr st, then control!

Controlling dust at its source is the key to efective control.

Adequate ventilation and the application of water, in sufcient quantity and at the correct location, can be efective ways to control dust. Since water will not control dust once the dust is airborne, water should be applied as near as possible to the point where the dust is produced in order to prevent it being carried away in the air current.

Water sprays are inefective unless they are operating efectively.

Capture dust by using scrubber systemson continuous miners and longwall beam stage loader crushers, and discharge to conveyor belt. Again, as with water sprays, if scrubber systems are not maintained adequately, they will be inefective.

21 In continuous miner panels, in particular, ventilation must be maintained at the face by erecting tightly ftting brattice or ducting, which should be extended systematically so that coal mine workers are never working ahead of the ventilation.

One mining practice that causes high concentrations of dust is working inbye ahead of ventilation ducting or brattice, and working on the return side of the shearer and/or advancing supports in longwall operations.

Operator positioning:

• In longwall operations, any task that has the potential to place coal mine workers on the return side of the shearer and/or advancing supports should be reviewed and controlled. A committed approach to efective utilisation of automation, particularly on bi-directional (BiDi) faces, is considered best practice in positioning operators and reducing their exposure to airborne dust.

22 • Cutting stone in development panels can potentially place operators at signifcant risk of inhaling silica dust. Operators on the vent side of the continuous miner are at higher risk if dust generated from the discharge is not controlled adequately. The cutting/loading cycle should be assessed to identify the parts of the cycle that have the potential to expose face operators to unacceptable levels of airborne dust (e.g. loading while cutting stone). For more information about dust control in underground coal mines, refer to Recognised standard 15: underground respirable dust control.

Measuring dust levels Regular monitoring allows coal mine operators to identify any areas or tasks within the mine that could potentially present a risk. It also provides data for mines to review the efectiveness of existing dust controls. For information on conducting a monitoring program on site, refer to Recognised standard 14: monitoring respirable dust in coal mines.

23 All site senior executives must ensure: • the mine has a respirable dust monitoring program as part of the mine’s safety and health management system • the respirable dust sampling plan has been developed by a competent person • respirable dust sampling is only conducted by a competent person • an investigation is conducted when a personal sample exceeds the exposure limit • the respirable dust monitoring program is reviewed by a competent person at regular intervals.

Personal dust monitoring Personal monitoring, also known as personal gravimetric sampling, allows coal mine operators to review the efectiveness of existing dust controls. It also helps mine operators identify any areas or tasks within the mine that could potentially present a risk to workers.

24 Determining respirable dust concentrations The approved sampling method adopted by the Queensland coal industry is personal gravimetric sampling according to Australian Standard 2985. Respirable dust is collected from the air within the breathing zone of a coal mine worker (close to the nose and mouth). The samples are taken by means of a small battery- powered pump worn by the mine worker. The pump is connected with a piece of plastic hosing to a sampling unit (or ‘cyclone’) that is clipped to the worker’s shirt within their breathing zone.

SAMPLER (sampling head) Sampling head positioned within breathing zone Breathing zone is a 300 mm hemisphere around the nose and mouth

SAMPLING PUMP

25 The cyclone sampling unit only allows respirable- sized dust particles to be collected—those particles small enough to be deposited in the lowest parts of the lungs. A steady stream of air is drawn through the sampling unit. The coarse dust is removed frst and only the very fne respirable dust is collected on a flter and weighed. The concentration of dust in the breathing zone of the worker can then be calculated.

Determining inhalable dust concentrations The method used to sample inhalable dust is similar to the personal gravimetric sampling method used for respirable dust according to Australian Standard 3640. The main diference is the sampling head. The inhalable sampling unit collects dust particles that could be deposited anywhere from the nose right throughout the lungs to the lowest part of the lungs. Typically, these dust particles range in size from 0.1 mm to the very smallest particles of 0.005 mm or less.

26 The method of dust sampling is designed to give the average result for the duration of the shift, and takes into account periods of high and low exposure to dust. Job rotation during a shift is benefcial to the overall health of workers due to the dilution efect of being exposed to a non-contaminated atmosphere following a short, but high, exposure to a dusty environment. One of the key factors involved in the onset of dust lung diseases is the total amount of respirable coal dust or respirable silica dust that a person has inhaled during their working life. It is not based on whether the person has been exposed to a high level of dust in a single event on one part of a shift, or due to a particular mining method.

27 Respiratory protective equipment Respiratory protective equipment (RPE) is the last line of defence in the control of airborne dust inhalation. On-site RPE programs should include: • regular training of coal mine workers in the correct selection, use and maintenance of RPE • identifcation of high-risk tasks and areas (such as cutting stone in development), which may require compulsory use of RPE • regular audits of RPE use during identifed high- risk tasks • regular ‘ft testing’ and consideration of clean-shaven policies for high-risk activities. Respiratory ft testing is recommended under AS/NZS 1715:2009: Selection, use and maintenance of respiratory protective equipment, and should be performed every 12 months.

Other control measures • Isolate or capture dust sources by sealing transfer points, beam stage loaders and crushers. • Control dust levels along travelling roads.

28 More information

To keep up to date with the latest advice on airborne dust exposure and other mine safety information, visit the Department of Natural Resources and Mines website at www.dnrm.qld.gov.au.

13 QGOV (13 74 68) dnrm.qld.gov.au facebook.com/MiningQld twitter.com/miningqld twitter.com/MiningAlertsQLD youtube.com/user/MiningQld

29 www.dnrm.qld.gov.au