Introduction to Task Manual
• What is Respirable Crystalline Silica?
• How Does Respirable Crystalline Silica Get Into the Body?
• What are the Known Health Effects Associated to Respirable Crystalline Silica Exposure?
• Where is Respirable Crystalline Silica Found?
• How to use the Task Guidance Sheets
The aim of this part of the Good Practice Guide on dust prevention is to reduce risks to which workers may be exposed from respirable crystalline silica.
This first section is an introduction to respirable crystalline silica and the task guidance sheets.
The task guidance sheets section contains a range of task guidance sheets which describe good practice techniques for various common and specific tasks. The general task guidance sheets apply to all of the industries which are signatories of the Agreement on Workers’ Health Protection through the Good Handling and Use of Crystalline Silica and Products containing it. The specific task guidance sheets relate to tasks concerning only a limited number of industry sectors. The management task guidance sheets relate to general management tasks and apply to all industries.
WHAT IS RESPIRABLE CRYSTALLINE SILICA?
By definition, respirable crystalline silica is the fraction of airborne crystalline silica dust that can penetrate the alveoli (gas exchange region) of the lung.
In the case of crystalline silica dust, it is the respirable fraction of the dust that is of concern for its health effects. These particles are so small that they cannot be seen with the naked eye. Once airborne, respirable dust takes a very long time to settle. A single release of dust into the workplace air can lead to significant exposure. In fact, in situations where the air is constantly stirred up and where no fresh air is being introduced, respirable dust may remain airborne in the workplace for days.
HOW DOES RESPIRABLE CRYSTALLINE SILICA GET INTO THE BODY?
Respirable crystalline silica enters the body when dust containing a proportion of crystalline silica is inhaled. When the particle size range of the dust is sufficiently small (such that the particles fall within the respirable fraction), the dust will travel deep into the lungs. It is at this point that respirable crystalline silica can cause health effects.
WHAT ARE THE KNOWN HEALTH EFFECTS ASSOCIATED TO RESPIRABLE CRYSTALLINE SILICA EXPOSURE?
The principal health effect associated to the inhalation of respirable crystalline silica is silicosis.
Silicosis is one of the most common types of pneumoconiosis. Silicosis is a nodular progressive fibrosis caused by the deposition in the lungs of fine respirable particles of crystalline silica. When one experiences prolonged overexposure, the body’s natural defence mechanisms may find it difficult to clear respirable crystalline silica from the lungs. An accumulation of dust can, in the long term, lead to irreversible health effects. These health effects involve scarring of the innermost parts of the lungs that can lead to breathing difficulties and, in some cases, death. Larger (non-respirable) particles are more likely to settle in the main airways of the respiratory system and may be cleared by mucus action.
Workers are rarely exposed to pure crystalline silica. The dust they breathe in the workplace is usually composed of a mixture of crystalline silica and other materials.
The response of an individual is likely to depend on:
- the nature and silica content of the dust
- the dust fraction
- the extent and nature of personal exposure
(duration, frequency and intensity, which may be influenced by the working
methods) - personal physiological characteristics
- smoking habits
WHERE IS RESPIRABLE CRYSTALLINE SILICA FOUND?
Occupational exposure to respirable crystalline silica can occur in any workplace situation where airborne dust is generated, which contains a proportion of respirable crystalline silica.
Occupational exposure to respirable crystalline silica occurs in many industries including quarrying, mining, mineral processing (e.g. drying, grinding, bagging and handling); slate working; stone crushing and dressing; foundry work; brick and tile making; some refractory processes; construction work, including work with stone, concrete, brick and some insulation boards; tunnelling, building restoration (painting) and in the pottery and ceramic industries.
HOW TO USE THE TASK GUIDANCE SHEETS
At each site, before commencing any work activity that may result in occupational exposure to respirable crystalline silica, employers must carry out a risk assessment to identify the source, nature and extent of that exposure.
When the risk assessment identifies that workers may be exposed to respirable crystalline silica, then control measures should be put in place to control exposures, in accordance with appropriate legal obligations.
Our task guidance sheets identify appropriate control measures that will assist employers in reducing exposure levels for many common work activities. When deciding which task sheet(s) to apply, priority should be given to the most significant sources of exposure to respirable crystalline silica in the workplace. Depending on the specific circumstances of each case, it may not be necessary to apply all of the control measures identified in the task guidance sheets in order to minimise exposure to respirable crystalline silica i.e. to apply CMD obligations (Article 4).
The task guidance sheets have been categorised for your convenience. Task sheet types, sections and sectors that they are relevant to, have been given visual treatments to help you find what you are looking for.
