Monitoring toxic atmospheres in confined spaces
Asphyxiation is one of the most common causes of fatalities in confined spaces, according to BOC Industrial Gases Australia. Due to the restricted airflow, exposure to toxic gases can create an unsafe atmosphere for workers. Additionally, asphyxiation can also occur when an individual falls into a narrow space and dies due to compression of the torso.
Almost any workplace can have confined spaces. While most do not require employees to spend extended periods of time inside the area, some occupations need workers to operate in confined spaces on a regular basis. This includes those working in mining pits, septic tanks, winery vats and grain silos.
All asphyxiation deaths are preventable if comprehensive safe work practices are followed. Tragically, almost 60 per cent of fatalities in confined spaces involve would-be rescuers acting out of haste to save a colleague, according to the American Occupational Safety and Health Administration.
Safe Work Australia defines a confined space as a partially or fully enclosed area that is:
– Not designed or intended for human occupation
– Devised to be at normal atmospheric levels when occupied by a person
– Likely to present hazards such as unsafe oxygen levels, contaminants that could cause a fire or explosion, asphyxiation due to unsafe levels of airborne contaminants or engulfment.
Reducing the risk of asphyxiation
In order to avoid the risk of fatalities due to asphyxiation, it is the responsibility of the business owner or employer to ensure their employees are following adequate safe work practices. Additionally, the Work Health and Safety (WHS) Act outlines the obligation of business operators to – as far is reasonably possible – minimise the hazards present in a workplace.
This includes responsibilities during the design and manufacturing stages of equipment, factories and other structures. If a structure includes a space that is likely to become an enclosed space, the designer, manufacturer or supplier has a duty of care to eliminate the need for any person to enter this confined area.
If this is not reasonably possible, these individuals must ensure there are adequate entry and exit points, along with sufficient ventilation.
Officers and managers within a business are also required to take precautions to minimise the risks to their employees. This includes taking steps to ensure the organisation and workers are compliant with the WHS Act and other regulations. An effective way of complying with this requirement is to provide comprehensive confined spaces training.
Additionally, employees themselves are expected to exercise care and due diligence regarding their own health and the safety of those around them. It is important for individuals to be aware of how their actions can affect not only themselves but also the colleagues and would-be rescuers around them.
A valuable example of the importance of compliance to these WHS relations is the historic case of three fatalities in an oil field in the US state of California.
In 1994, an oil field worker entered an oil well cellar to switch off a water valve during a procedure to create perforations in the water disposal pipe.
This employee was quickly overcome by carbon monoxide and collapsed. A second worker then entered the cellar to rescue his colleague but also fell. A third individual looking into the cellar to offer assistance then also collapsed.
These three workers were then pulled from the cellar by a group of other employees also working in the area. Unfortunately, all three were pronounced dead later on that day. Two of the rescuers were also hospitalised but survived the incident.
Investigations found the unfortunate fatalities on this day could have been avoided if the workers had been wearing any personal protective equipment (PPE). Additionally, the hasty entry into the cellar by the untrained rescuers meant two additional unnecessary deaths.
The employer was quickly found guilty of breaches to local occupational health and safety laws due to the fact that no prior confined spaces training was given to the employees working on the gas well cellar. In addition to this, no PPE was available anywhere on the worksite and atmospheric testing had not been carried out.
Since this time, OHS standards have improved and most workplaces supply adequate PPE and safety training. However, these deaths should not be forgotten, as they serve as a stark warning of how a momentary lapse in judgement can lead to a number of tragic fatalities.
It is therefore important to ensure your workers know what to do if a toxic atmosphere is discovered in the workplace.
How to manage a toxic atmosphere
The simplest way to minimise the risk of illness or death due to toxic atmospheres in a confined space is to provide adequate training to all staff to ensure they know the correct procedures to deal with these situations.
This will prevent employees from taking ill-informed actions, such as entering a space to rescue a coworker without the correct safety equipment.
Sufficient training will also teach individuals how to recognise and report potential hazards in the workplace, which can help prevent toxic contamination in the confined space altogether.
Additionally, employers should encourage regular atmospheric testing of confined spaces. Ideally, confined spaces should be tested for toxic contaminants and oxygen content each time an employee is allowed entry.
This can include monitoring for gases not typically expected in a particular workplace. In the 1994 case above, carbon monoxide was not considered a relevant hazard in oil well perforation. This means that even if the employees had performed the required tests, they may not have detected the high levels of CO is the atmosphere.
It is also important to ensure the atmospheric testing is designed to monitor both heavy and light gases. If a toxicity monitoring system is fixed to the lower level of a confined space, it may miss lighter gases filling the higher reaches of the area. Similarly, a monitoring process that only reaches the top of the space will fail to pick up any heavy gases and contaminants closer to the floor.
Adequate ventilation is also a key component in preventing illness, injuries and death in confined spaces. Allowing sufficient air flow can reduce the concentration of toxic gases, stabilising the atmosphere at a healthier level and minimising the risk of asphyxiation.
Where ventilation is not possible or effective, employees entering a confined space must be provided with adequate PPE. This includes durable clothing, harnesses and respiratory protective equipment (RPE) – such as breathing apparatuses and masks.
A harness attached to a guide wire will allow a disoriented worker to find their own way back out of a space with minimal exit and entry points. Additionally, it may enable would-be rescuers to pull the employee from harm's way without needing to enter the confined space.
Durable and protective clothing should help prevent toxicity caused by contaminants coating the skin of employees. Some airborne particles can continue to pose a risk long after an employee has left the confined space when carried on clothing or skin for long periods of time.
RPE should always be used as a last resort. It is more effective to ensure safe levels of oxygen are present before sending an employee into a confined space. RPE is an essential measure when contaminants are unidentified or it is not possible to minimise the risks in enclosed areas.
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