There are many dangers that could be present for someone working within confined spaces, some of these are as a result of what the confined space or area around it is commonly used for, whilst other dangers are created through the work being carried out. Below are just some of the dangers that can pose a threat to the wellbeing of confined space workers that should be evaluated by a responsible person before any work is carried out.
Fire or Explosion
This could occur due to a rise in oxygen levels which could be caused by, for example; a leak from an oxygen cylinder as part of welding equipment. There could also be a risk of ignition of airborne contaminants coming from adjoining plant or processes that haven’t been effectively isolated.
Besides naked flames the ignition for a fire or explosion could come from equipment that causes sparks such as welding tools or static from inappropriate PPE or electronics.
Toxic Gas, Fume, Vapour or Lack of Oxygen
Where there is a risk of gas fume or vapour or lack of oxygen causing loss of consciousness.
Fumes from previous processes or storage within a confined space could remain as well as sludge and other deposits being disturbed whilst cleaning. Leaking pipes that have not been isolated effectively could be contaminating a confined space.
Gas and fumes coming from sewers, manholes and contaminated ground. Leaks could come from under vessel linings as well as from welding, cutting, lead lining, brush and spray painting, moulding using glass reinforced plastics, use of solvents or adhesives from products of combustion. Hot work taking place on the outside of the confined space could generate fumes or it could also come from machinery that is being operated from outside the confined space.
Oxygen deficiency could occur when using inert gases such as nitrogen for purging a confined space to remove toxic gas, fumes or vapour. Naturally occurring biological processes such as breathing can consume oxygen particularly in poorly vented areas. Carbon dioxide being produced from materials such as limestone chippings getting wet can also cause a lack of oxygen to occur.
The Ingress or Presence of Liquids
Large quantities of liquids can cause drowning when flowing or being present in a confined space. The nature of the liquid that is present could cause serious injury such as their corrosive or toxic elements.
Solid Materials Which Can Flow
Free flowing materials can cause asphyxiation.
Some materials such as grain in silos can submerge a person which will prevent them from breathing. Other products such as sugar, flour, coal dust and any granular or powder form can be extremely dangerous in large quantities.
Presence of Excessive Heat
Where work is undertaken in warm or hot environments there is a possibility of the inner core body temperature rising which could results in becoming unconscious. A slow build-up of body temperature can cause heat stress, and if no action is taken to cool the body temperature down then this could lead to heat stroke. A consideration should be made in relation to PPE such as helmets or tunics that they could add additional risk to the rise in the body temperature.
The method used for measuring heat stress to a person is known as THE WET BULB GLOBE TEMPERATURE INDEX (WBGT). When people work in these types of environments, we need to consider the workload and time inside the confined space. The American Conference of Government Hygienists have drawn up standards which give an idea on the type of rest periods for the temperature and difficulty of work.
Other Hazards to Consider
Other hazards that need to be considered include the presence of electricity, mechanical equipment, weather conditions, noise levels and dust as well as working place hazards such as slips and trips, overcrowding of confined spaces and biological hazards that could cause diseases such as leptospirosis, legionnaires disease, hepatitis A or hepatitis B.
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