RESPIRATORY HEALTH


INVISIBLE FORCES


Simon Field, Technical Specialist at science-based technology company 3M, discusses the respiratory hazards welders face and how to combat them


Welding is an inherently dangerous task that can cause life-changing injuries, long-term health problems and even death without proper protection measures in place.


Most people are aware of the more obvious risks associated with this practice, such as exposure to excessive heat and damaging ultra violet (UV) light.


However, the potential respiratory hazards are too often forgotten, primarily because they are invisible and their effects take longer to manifest.


Every year, between 40 and 50 welders in the UK are hospitalised because of metal fume inhalation, according to the Health and Safety Executive (HSE). This figure includes around two welders who die of pneumonia annually, the HSE says, citing a 2009 study.


In order to protect welders against potential respiratory hazards, it is important to first understand the hazards themselves.


During welding, metal is heated to such high temperatures that it becomes a gaseous mixture known as metal fume, before re-solidifying when removed from the weld pool.


The fume cloud comprises a mixture of gases and tiny airborne particles. The visible part is made mostly of metal, metal oxide and flux particles.


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As these particles dissipate, they quickly become invisible to the eye, which can create the false illusion that no hazard remains.


However, it is actually the smallest particles that pose the greatest risk, as they can most easily penetrate the lungs.


Once in the bloodstream, these particles can cause metal fume fever, a respiratory illness with flu-like symptoms, such as headaches and joint pain.


The pronounced short-term effects may dissipate after just 24 hours. However, workers who regularly breathe in smaller doses of weld fume may experience regular symptoms without knowing why. Some may wrongly attribute it to overworking.


Prolonged exposure can also lead to other respiratory conditions, such as asthma, as well as increasing the sufferer’s vulnerability to illnesses like colds and pneumonia.


To protect welders, employers must have appropriate control measures in place, starting with ventilation.


Some companies use push and pull ventilation systems, but local exhaust ventilation (LEV) systems are more common. These use a large vacuum hose, either at the work area or on a moveable arm over a rig, to extract the weld fume.


In some cases, such systems might be adequate by themselves. However, respiratory protective equipment (RPE) will often also be necessary.


Within industry, powered air respirators are the most commonly used type of RPE. If these are required, welders should use models classified by the HSE as ‘TH2’, which has an Assigned Protection Factor (APF) of 20.


Welders who switch between tasks, such as grinding and welding, are also advised to use a head-top with an auto-darkening visor and a flip-up welding shield. This way, the wearer will always be protected by a complete respiratory system and the grinding visor underneath, even with the shield flipped up. Auto-darkening welding shields that feature a grinding mode are another good solution.


Wherever RPE is required, it is important that welders wear it for the entire duration of the hazard, not only when they are welding. Welders should remember that respiratory hazards may remain even when the weld fume is not visible.


If LEV is in place, this may provide adequate protection once welding has stopped, depending on the system’s effectiveness. However, if the system is not adequate by itself, it becomes even more important to use RPE properly.


www.3M.co.uk/safety www.tomorrowshs.com


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