The jewellery industry has processes, which require the use of acids and other hazardous substances; one of the acids used is sulphuric acid, a mineral acid composed of sulphur, oxygen and hydrogen, with molecular formula H2SO4.
It is generally used in the gold industry for metal extraction, refinement and processing and is highly corrosive. Short term exposure from sulphuric acid can affect the eyes, skin and respiratory tract, high concentrations may cause lung oedema and also asthma-like reactions (ILO-ICS 2016). Long term exposure may cause effects on the lungs and possible tooth erosion with repeated or prolonged exposure. Inhalation of strong inorganic acid mists, which may include sulphuric acid, cause cancer of the larynx. Evidence suggests that exposure may be associated with lung cancer in humans (IARC 2012).
Respiratory Protective Equipment (RPE)
RPE is a particular type of Personal Protective Equipment (PPE) and is used as the means of protection from inhalation of sulphuric acid mist and other hazardous substances. RPE should only be used where adequate control of exposure cannot be achieved by other means, in other words, as a last resort on the hierarchy of control. RPE should only be used after all other reasonably practicable control measures have been taken, firstly eliminating the hazard at the source. RPE is considered a last resort because it only protects individual workers and is prone to failure or misuse. (i.e. wearing the wrong RPE for the job.)
Types of RPE Commonly Used
Filtering Device Types (Negative Respirators)
These use filters to remove the contaminants in the workplace air. In a negative pressure device, one or more air purifying filters are attached via an inhalation valve to a tight-fitting facepiece. The negative pressure relative to the ambient air outside the respirator is created by inhalation of air, drawing the contaminated air through the purifying filter.
Breathing Apparatus (BA) Types (Positive Respirators)
Powered air purifying respirators, supplied air and self-containing breathing apparatus are all positive pressure devices. The pressure on the inside of the respiratory inlet exceeds the ambient air pressure outside the respirator. As a general rule, positive pressure devices are used for more hazardous exposures.
Selection of RPE
The correct selection of appropriate RPE for the task undertaken is one of the most important steps in the RPE lifecycle process. Failing to select, conduct a fit-test, use, store and maintain correctly the RPE will lead to exposure of hazardous substances.
The four areas that need to be considered are:
- Equipment factors – is it adequate for the task, is it is good working order?
- Work environment factors – is the atmosphere dangerous, what type of air contaminants?
- Task-related factors – vision, communication, other PPE, duration of wear…etc.
- Individual factors – physical characteristics, facial characteristics, medical fitness of the wearer.
Other considerations are the type of filter used, the protection factor of the equipment, the fit for the employee and how it is stored and maintained.
Applicable legislation is found in Local Order 61, (1991) and supported by Dubai Municipality technical guidelines specifically in regards to the use of respiratory equipment (TG 15 2010) and the metal finishing industry (TG 23 2010).
For more information on any HSE issues, please contact HSE@dmcc.ae.