Welding–The Risks

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Taille du fichier : 1.6 Mo (1711590 octets)
Date : 2002/09/18 13:23:53
Taille de l'image : 2560 x 1920 pixels
Résolution : 300 x 300 ppp
Profondeur en bits : 8 bits/canal
Attribut de protection : Désactivé
Attribut Masqué : Désactivé
ID de l'appareil : N/A
Appareil : E5000
Mode de qualité : FINE
Mode de mesure : Multizones
Mode d'exposition : Programme Auto
Speed Light : Non
Distance Focale : 21.4 mm
Vitesse d'obturation : 1/14.2 seconde
Ouverture : F4.8
Correction d'exposition : 0 IL
Balance des blancs : Auto
Objectif : Intégré
Mode Synchro-Flash : N/A
Différence d'exposition : N/A
Programme Décalable : N/A
Sensibilité : Auto
Renforcement de la netteté : Auto
Type d'image : Couleur
Mode Couleur : N/A
Saturation : N/A
Contrôle Saturation : 0 Normal
Compensation des tons : Auto
Latitude (GPS) : N/A
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Welding is one of the most common activities carried out in industry. HSE estimate that there are around 190,000 welders in UK. However, this is likely to be an underestimate of the total number of workers who carry out welding as there is likely to be a large number who do a small amount of welding on an occasional basis.

There are a number of health hazards associated with welding in particular:

  • Fume
  • Gases, including ozone and, with MIG and TIG welding, inert gases that can present a problem when working in confined spaces
  • UV radiation from the welding arc. This can effect the eye (“arc eye”) and skin and is also responsible for the generation of ozone from atmospheric oxygen.

The main health hazard with many welding operations – particularly MMA (stick) and MIG welding – is the welding fume. This consists of very fine particles of metal oxides, mainly arising from the welding rod or wire.

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The composition of the fume varies depending on the metal being welded. With mild steel it will mainly consist of iron oxide but there is also likely to be a small percentage of manganese which is used in welding rods. Repeated exposure to low concentrations of manganese have been shown to affect the nervous system and the Workplace Exposure Limit for manganese will be reduced significantly in 2018. Stainless steel welding is particularly hazardous as the fume contains nickel and chromium VI oxides which are highly toxic if inhaled – both are carcinogens and can also cause occupational asthma.

As well as the fume (particulate), Arc welders will also be exposed to gases. Ozone is produced by the action of the UV from the arc on oxygen in the air. It is highly irritant to the eyes and respiratory system. In some cases, particularly with thicker plate, atmospheric nitrogen can be converted to highly irritant nitrogen oxides. With MIG and TIG welding the inert gas used to stop the weld oxidising will be released. This should not present a risk when welding outdoors or in a well ventilated area, but can present a serious risk of asphyxiation in a confined space.

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The UK Health and Safety Executive estimate that exposure to welding fume causes more than 150 deaths due to cancer every year. Exposure to the fume and gases can also cause other diseases including

  • Pneumonia
  • Metal fume fever
  • COPD
  • Asthma

Many welders are exposed unnecessarily to welding fume. Control measures are available – but it’s important to make sure the right controls are used – there is not one solution that will be effective in all cases.

Dark Satanic Mills

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Many people when they get to a certain age start to wonder where they came from. That was certainly true for me so a few years ago I started to research my family tree. Although there were a few surprises my research confirmed that I my family were ordinary workers. I wanted to find out about my roots, about my ancestors, where they came from and how they lived. And as an occupational hygienist I couldn’t help but be interested in what they did for a living and their working conditions.

Halifax Mill Chimneys

Coming from Lancashire it wasn’t a surprise to find that many of my ancestors who lived in the 19th and 20th Centuries were employed at some time during their lives in cotton mills. And working in cotton mills they were faced with a whole host of health risks.

I’ve always been interested in industry and when I was a boy my mother arranged for me to have a look round the mill where she worked. The first thing that hit me when I walked in the mill was the tremendous noise. Levels in weaving sheds were likely to be well above 90 dBA – often approaching, or even exceeding 100 dB(A). Communication was difficult and mill workers soon learned how to lip read and communicating with each other by “mee mawing” – a combination of exaggerated lip movements and miming

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Not surprisingly many cotton workers developed noise induced hearing loss – one study in 1927 suggested that at least 27% of cotton workers in Lancashire suffered some degree of deafness. Personally, I think that’s an underestimation. This is how the term “cloth ears” entered the language – it was well known that workers in the mills were hard of hearing.

This lady is a weaver and is kissing the shuttle – sucking the thread through to load the shuttle ready for weaving.

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This practice presented a number of health risks – the transmission of infectious diseases, such as TB, but as the shuttle would be contaminated with oil, and the oils used then were unrefined mineral oil – there was a risk of developing cancer of the mouth.

Exposure to oil occurred in other ways particularly for workers who had direct contact with machinery or where splashing of oil could occur. There was a high incidence of scrotal cancer in men who operated mule spinners – and this was a problem even in the 1920s. In earlier times workers in mills had to work in bare feet as the irons on their clogs could create sparks which could initiate a fire due to the floorboards being soaked with oil. Contact with these very oil soaked floorboards led to cases of foot cancer.

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And of course there was the dust. Exposure to cotton dust, particularly during early stages of production, can lead to the development of byssinosis – a debilitating respiratory disease. An allergic condition, it was often known as “Monday fever” as symptoms were worst on Mondays, easing off during the week. A study on 1909 reported that around 75% of mill workers suffered from respiratory disease.

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The worst areas for dust exposures were the carding rooms where the cotton was prepared ready for spinning, but dust levels could be high in spinning rooms too.

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Although control measures started to be introduced in the 1920’s workers continued to be exposed to dust levels that could cause byssinosis. Studies in the 1950’s showed  than more than 60% of card room workers developed the disease as well as around 10 to 20% of workers in some spinning rooms.

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A lot of work was devoted to studying dust levels, developing standards and control measures by the early pioneers of occupational hygiene in the UK and I’m sure this contributed to improved conditions in the cotton industry in the UK. I’m not sure I’d like to have to operate their dust sampling kit though – it certainly wasn’t personal sampling!

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Today things are different. The carding machines, spinning frames and looms are silent and have been sent for scrap. The mills have been abandoned and are derelict or demolished or have been converted for other uses.

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Cotton is still in demand but it’s a competitive market and the work has been moved to other countries where labour is cheap and standards are not as high – Africa, China and the Indian sub-continent. Another consequence of globalisation. Although you could say that the industry is returning to where it originated in the days before the industrial revolution. Sadly, conditions and working methods in many workplaces in the developing world are primitive and controls are minimal. It seems like the lessons learned in the 20th Century in the traditional economies are rarely applied so not surprisingly those traditional diseases associated with the industry are re-emerging in developing economies.

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Studies carried out in recent years have shown high incidences of byssinosis in some mills developing countries. One study in Karachi, Pakistan in 2008 found that among 362 textile workers 35.6% had byssinosis. (Prevalence of Byssinosis in Spinning and Textile Workers of Karachi, Pakistan, Archives of Environmental & Occupational Health, Vol. 63, No. 3, 2008 ). A study of textile workers in Ethiopia published in 2010 showed a similar proportion – 38% had developed byssinosis,  with 84.6% of workers in the carding section suffering from the disease

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Another study, this time into textile workers’ noise exposures in Pakistan indicated noise levels in the range 88.4-104 dB(A). 57% were unaware that noise caused hearing damage and almost 50% didn’t wear ear defenders

William Blake wrote of “Dark Satanic Mills” in 1804. This was still a fair description of the working conditions in Lancashire when my ancestors worked in the mills. And I believe its valid today in many workplaces in the developing world.

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It’s not easy to get accurate figures on occupational health in the UK and so much more difficult in the developing world. The best estimate we have (and it’s likely to be an underestimate) is that 2.3 million people die due to accidents at work and work related disease (World health Organisation). And the vast majority of these are due to ill health

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Some occupational hygienists might take a dispassionate, academic interests in dust exposure. But I think most of us are motivated by a genuine desire to prevent ill health at work and improve working conditions. Many of us work in countries where conditions although far from perfect are relatively good. But can we turn a blind eye to what’s happening in the rest of the world?

Personally, I think it’s something we need to be thinking about.

Cupola furnace

cupola Wigan

I took this picture recently of a cupola furnace at a small foundry in Wigan. Scrap metal and coal are loaded into the top of the furnace and the coal set alight to melt the scrap and produce molten metal which is used to manufacture iron castings.

As there is insufficient oxygen for complete combustion, carbon monoxide is generated. Hydrogen sulphide can also be produced due to the presence of sulphur in the coal. Both of these gases are highly toxic and have to be extracted to minimise the risk to the operators. Some of the gases dissolve in the molten metal and can gas off as it cools, so there can be some risk during the casting operation itself.

This is a good example of how hazardous substances can be generated during a process and which are often forgotten by inexperienced or untrained people carrying out health risk assessments.

A number of years ago I got involved with a company (NOT the one shown in the picture, I should point out) where a worker had been exposed to high concentrations of carbon monoxide when inspecting the furnace when a leak occurred. The company concerned had employed a safety consultant to carry out COSHH assessments for them. Unfortunately he based his assessments on the material data sheets for the substances bought by the company. There were no data sheets for carbon monoxide or hydrogen sulphide as they aren’t bought in so there was no mention of two of the most serious risks in he foundry – i.e. potential exposure to the gases. There were other hazards he didn’t consider too – metal fume created during melting and casting and exposure to respirable crystalline silica during “fettling” (the grinding of the finished castings to remove rough edges) – because again, these substances are created by the process and are not bought in.

Although most people seem to think that COSHH requires an assessment to be carried out for substances, this isn’t actually the case – the assessment should actually cover the “risks created by work” where workers can be exposed to hazardous substances. It’s best to start by considering the process and what workers and others can be exposed to – both bought in substances and any that can be generated by the process itself. Quite often it is the latter that present the most significant risks, as is the case with the cupola furnace and other foundry operations. Listing the substances bought in and using the supplier’s data sheets as the basis of the assessment is likely to lead to significant risks being missed.

Note: COSHH is an acronym for the British Control of Substances Hazardous to Health Regulations 2002