Dust (Including Cotton and Wood Dust)

Dust can be formed from a wide range of sources such as construction work or machinery.

There are many different types of dusts for example flour, grain, wood, coal, metal and cotton. Some dusts can be poisonous and some are explosive. There are some irritant dusts that can cause some minor problems and there are respirable dusts that can damage your lung tissue. Most dusts are too small for the naked eye but all are either avoidable or can be controlled by precautions taken to ensure worker safety.

IT’S THE LAW!

Airborne dusts and particles can present a risk to the health and safety of employees and others in the workplace. Clause 51 of the NSW OH&S Regulation states it is the responsibility of the employer to ensure that no person at a place of work is exposed to an airborne concentration of an atmospheric contaminant that exceeds or breaches the standard referred to in or determined under Clause 51 subclause (2) of the NSW OH&S Regulation.

CONTROL MEASURES

There are a few simple steps that are set out to minimise the effects that dust hazards can have in the workplace from machinery and equipment, to safe work procedures and respirators. These are set out on the following pages.

WORKPLACE MONITORING

To protect the health of workers, exposure measurements should be made from unbiased and representative samples of actual worker exposure.

EXPLOSION HAZARDS

Organic dusts, coal dust, metal dust and sulphur dust can be an explosive hazard. If a dense cloud of any of these dusts forms, or if layers of these dusts accumulate, then one spark (or even a hot surface) can ignite it.

A GUIDE TO DUST HAZARDS

Your body protects you against some dust. Not all the dust that you breathe in gets into your lungs. The larger particles are filtered out in your nose and the tubes leading to your lungs.

These particles are coughed up, spat out or swallowed.

Only the finest dust particles reach your lungs. Usually these dusts are too fine for you to see them. These fine dust particles, which can enter deep into the lungs, are called ‘respirable dust’.

Much of the dust that does get into your lungs is cleared out by the lungs own defence system. Macrophages (Large immune system cells that kill foreign invaders) in the lungs virtually ‘swallow’ some dust particles and are then carried out of the lungs. Proteins in the lungs can also ‘neutralise’ some dust particles. But your body cannot protect you against all dust particles.

HEALTH HAZARDS

Irritant dust hazards Even the larger dust particles that don’t get to the lungs can cause problems. Dust in the nose and in the tubes leading to your lungs can irritate them, causing rhinitis or bronchitis.

Respirable dust hazards If too much dust enters the lungs it can overwhelm the lungs’ own defences. Dust particles and dust-containing macrophages can collect in the lung tissues and damage them.

Some types of dust, such as silica and asbestos, cause permanent scarring in the lungs. This is called fibrosis. Some dusts, such as asbestos, cause lung cancer. Some dusts (for example many animal, grain and wood dusts) can trigger an allergic reaction by the lungs. These types of dusts can also trigger asthma attacks.

EXPLOSION HAZARDS

Organic dusts (e.g. flour, grain, wood dusts), coal dust, metal dust and sulphur dust can be an explosion hazard. If a dense cloud of any of these dusts forms, or if layers of these dusts accumulate, then one spark (or even a hot surface) can ignite it.

These conditions can occur in handling and storage equipment, so it’s important for all possible sources of ignition to be removed and kept away from these areas (e.g. welding, slipping belts, sources of static electricity). Electrical equipment in these areas should be ‘dust ignition proof rated’.

DUST HAZARD EFFECTS

Silica

  • Severe breathlessness,
  • Bronchitis,
  • Scarred lungs
  • Lung cancer

Coal

  • Severe breathlessness.
  • Scarred lungs (coal pneumoconiosis)

Asbestos

  • Cancer (mesothelioma, lung cancer)
  • Scarred lungs

Synthetic Mineral Fibres

  • Irritants
  • Fibres made from (SMF) products e.g. ceramic fibres, rockwool and fibreglass, may possibly cause cancer if the fibres are very fine

Cotton

  • Severe breathlessness (bysnossis)

Wood

  • Allergic reaction and or asthma.
  • Nasal cancer

Other animal and vegetable dusts

  • Allergic reaction and or asthma.
  • Symptoms include breathlessness, dry cough and sore throat.

CONTROL MEASURES

1. Safe machinery and equipment: Dusty work processes should be isolated if possible. An exhaust ventilation system is often needed to suck dust away.

Vacuum tools or negative pressure portable tools are often useful. Ordinary household vacuum cleaners don’t effectively trap respirable dust particles. You need a vacuum with a HEPA (high efficiency particulate air) filter. Where there is an explosion hazard you need an explosion proof vacuum cleaner.

2. Safe procedures: Standardised working procedures are needed in areas where dust can be a problem. Information and training is important. Warning signs may be needed. Good housekeeping procedures (e.g. vacuuming or wet sweeping dusty work areas) are needed.

3. Respirators: If steps 1 and 2 are not completely effective then an approved respirator is needed. Make sure that (A) it fits properly and is the right kind of respirator (B) training in how to use it is provided and (C) maintenance checks are carried out.

HOW WORKPLACES ARE MONITORED

To protect the health of workers, exposure measurements should be made from unbiased and representative samples of actual worker exposure.

As part of the risk assessment process employers need to measure the concentration of airborne contaminants, these include dusts. The airborne concentration of contaminants may vary considerably at different times and from place to place. Air samples taken at fixed locations in the working environment are only of limited use in assessing the risks posed to workers from a particular contaminant. These samples may be essential in the design of, or assessing the effectiveness of, control measures.

Proper evaluation of worker exposures may require a substantial commitment of personnel, sampling equipment and analytical resources, along with an appropriate way of sampling that captures a realistic measure of actual employee exposure to dust.

COTTON DUST

Cotton dust is dust present in the air during the handling or processing of cotton. This dust may contain a mixture of many substances including ground up plant matter, fiber, bacteria, fungi, soil, pesticides, non-cotton matter, and other contaminants.

COTTON DUST HEALTH EFFECTS

Exposure to cotton dust can mean serious health problems. The first symptoms of disease are difficulty in breathing or perhaps tightness across the chest, which is particularly noticeable on the first day back at work after a worker has been off for a few days. Workers also cough up phlegm or mucous. If exposure above the OHS limit (see Fact Sheet Air Quality for information on exposure limits) continues workers may develop byssinosis, also known as “brown lung” disease.

While earlier breathing difficulties may be reversible, damage at the advanced stages of the disease is permanent and disabling. Workers who develop brown lung may have to retire early because they are so short of breath they cannot do their normal jobs or even carry out simple tasks.

WOOD DUST

People exposed to wood dust at work are at greater risk of developing nose, sinus, throat, lung, and skin conditions. Health problems may take a long time to develop, and are most common in people who have spent many years at workplaces exposed to high concentrations of wood dust.

Dusts from hardwoods are usually finer and therefore more easily inhaled. Those most at risk are at indoor workplaces with inadequate dust extraction systems.

HAZARDOUS WORK ENVIRONMENTS

Hazardous amounts of wood dust may be generated by jobs like floor sanding, furniture sanding, wood turning, routing, sawing, sweeping and emptying dust filters. Dust hazards exist in varying degrees from timber felling in the forest to furniture manufacturing and cabinet making in factories and workshops. The main hazards occur where there is poor natural or mechanical ventilation.

HOW CAN WOOD DUST HARM YOU?

Studies in Australia and elsewhere have linked wood dust in workplaces to asthma, bronchitis, lung, sinus and throat irritations, shortness of breath and skin problems. The IARC (International Agency for Research into Cancer), after researching nasal cancer among woodworkers in Europe, has classified wood dust a human carcinogen.

Wood dust from timbers such as beech and oak, which is fine enough to be inhaled, are known to cause cancer. Other species such as, birch, mahogany, teak and walnut may also be capable of causing nasal cancer. As this is a rare form of cancer, the risk is small and generally restricted to the finishing trades where the dust is fine.

Freshly cut trees contain large amounts of microbes, mainly moulds. The number of these increase if the logs are stored outside and under moist or humid conditions.

The microbes can cause inflammation of the airways during debarking, sawing and transportation.

CONTROLLING WOOD DUST HAZARDS

The best way of reducing wood dust at a workplace is by using machines that are enclosed or fitted with effective local exhaust ventilation (LEV). LEV involves locating an extraction outlet as close as possible to each identified source of dust, and having sufficient air velocity to draw dust away before it becomes airborne.

On some machines with a single cutting, grinding or sanding face, there may be several sources of dust thrown, drawn or blown from different parts of the machine. Ideally, each dust source should be controlled by the LEV system.

While most wood dust is from machines, hand sanding fine furniture can be one of the dustiest jobs at the workplace. Hand sanding generally requires the use of respiratory protection.

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