Welding–The Risks

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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.

Lung Disease and Work

The Lane Lecture is an annual event hosted by the Centre for Occupational and Environmental Health at the University of Manchester. Named in honour of Ronald Lane, the first ever Professor of Occupational Health at the University.

This year the lecture was delivered by Professor David Fishwick, Chief Medical Officer and Co-Director of the Centre for Workplace Health. His talk was entitled The lungs at work: from cotton mills to composites? One of the key messages is that diseases such as byssinosis and silicosis are not historic issues.

In 1890 there were more cotton mills in Manchester than in the rest of the world. But that is no longer the case – the industry has been transferred overseas, particularly to developing economies. So byssinosis, which is caused by exposure to cotton dust, is no longer a problem in the UK. However, it’s a different matter in those countries where cotton is now produced.

Studies carried out in recent years have shown high incidences of byssinosis in some mills in 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 )

Professor Fishwick also focused on Silicosis, the oldest known occupational lung disease which remains a significant problem across the globe, including the UK. This debilitating disease is caused by exposure to respirable crystalline silica (particles smaller than 10 microns) which can occur in many industries, including mining, quarrying, brick and tile manufacture, stone masonry, glass manufacture, tunnelling, foundries, ceramic manufacturing and construction activities.

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The risk is clearly associated with the level of exposure and it only takes a regular exposure to very low concentrations to cause the disease. The US Occupational Safety and Health Administration (OSHA) estimates that 30% of workers with 45 years of exposure to 0.1 mg/m3 respirable crystalline silica dust will develop silicosis (see page 16394 of the “Final Rule”). Yet 0.1mg/m3 (respirable dust) is the current Workplace Exposure Limit for crystalline silica in the UK.

Clearly the current WEL is not a “safe level” and there is a very strong case for reducing it. In the US OSHA has recently announced a reduction in their Permitted Exposure Limit for silica down to 0.05 mg/m3. No change is proposed in the UK. The HSE’s view is that there are difficulties accurately measuring exposures lower than 0.1mg/m3, so it would be difficult to demonstrate compliance, and that, in any case, employers have a duty to not only meet the exposure limit but the apply “principles of good control practice” set out in Schedule 2A of the Control of Substances Hazardous to Health Regulations. Not everyone agrees with them, however.

As well as causing silicosis, respirable crystalline silica is a carcinogen. It’s estimated that in the UK it causes around 600 deaths per year from lung cancer shows  with 450 of these occurring from exposures in the construction sector.

Occupational cancer deaths by cause in Great Britain, 2005 (HSE)

Personally, I’d like to see the WEL reduced and research done to develop better sampling methods which will allow low levels of exposure to be evaluated. I do sympathise, though, with their emphasis on control. Reducing exposure by introducing improved controls is the key to preventing workers from developing industrial disease. Measurement can help us to understand exposure and identify where improved controls are needed. But sometimes the problem is obvious and in those cases it’s better to spend time, effort and money sorting it out, particularly when there are well established solutions available.

Health in Construction

A couple of weeks ago I travelled down to Birmngham to give a talk on behalf of the BOHS Breathe Freely initiative at the Health and Wellbeing event at the NEC. The Title of the talk was Managing Health in Construction – What Good Looks Like. An annotated version of the slides I used during the talk are now available on Slideshare

To prepare for the talk I did a little research on the meaures that are readily available to control exposure to contaminants, particularly dust, during common activities on construction sites. A number of studies have been done, both on-site and in the laboratory to assess the effectiveness of water supression and on-tool extraction for power tools. These studies have confirmed just how they can be.

For example

  • A large scale study in Ireland by Healy et al showed that the use of local extraction built into on-tool shrouds could reduce dust exposures by up to 99%
  • Laboratory tests by Thorpe et al showed water suppression on cut-off saws reduced dust levels by up to 99%

Despite this, in a large proportion of cases these engineering controls are not being used with reliance placed on respiratory protection which is often incorrectly used and inadequately managed. So one of the main aims of the BOHS Breathe Freely initiative is to raise awareness of the types of controls that can be used to reduce exposure. Hopefully in the not too distant future we’ll see water supression and on-tool extraction become the norm rather than the exception.

 

References

Measurements of the E€ectiveness of Dust Control on Cut-off€ Saws Used in the Construction Industry. Thorpe et al. Ann Occup Hyg Vol. 43, No. 7, pp. 443-456, 1999

An Evaluation of On-Tool Shrouds for Controlling Respirable Crystalline Silica in Restoration Stone Work.  Healy et al. Ann Occup Hyg 2014;58:1155-1167

Toxic Art – Alexander Calder’s Mercury Fountain

As an occupational hygienist, when visiting the Alexander Calder exhibition at Tate Modern last week I couldn’t help but stop and take notice of the pictures and description of one of the works created by this American artist well known for his mobiles and other “kinetic sculptures” . A mercury fountain.

While I was looking at the display, I overheard a comment by a young woman to her partner as they too read about this work

“It couldn’t have been real mercury could it. That would be dangerous”

I couldn’t help responding

“It was, and it is ”

Mercury, the magical Quicksilver, has been known since ancient times. A metal that’s a liquid at room temperature that flows like water.  Being a liquid, vapours are given off which can be inhaled and it can also be absorbed through intact skin. It’s highly toxic, affecting the brain, gastrointestinal system and kidneys. It’s particularly noted for causing neurological and behavioural disorders due to brain damage. Symptoms include tremors, insomnia, memory loss, neuromuscular effects, headaches and cognitive and motor dysfunction. In Victorian times mercury compounds were used in the manufacture of felt for hats and the workers in that industry were particularly affected. This is said to have inspired Lewis Carroll’s “Mad Hatter” from Alice’s Adventures in Wonderland. This was disputed by the esteemed Professor Hugh Waldron back in 1961, but the myth persists.

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The exhibition website tells us the story of the fountain’s creation

In 1937 Calder was one of the contributors to the Pavilion of the Spanish Republic designed by Josep Lluís Sert for the International Exposition in Paris, where his Mercury Fountain was installed in proximity to Picasso’s painting Guernica. In the middle of the Spanish Civil War, Calder showed his support for the embattled Republic by creating a fountain that would run with mercury from the mines at Almadén – a valuable economic and strategic resource. (Tate website)

A 2007 study of historical exposures of the workers in Almadén mines to mercury indicated that had been very high

In the mine, the highest exposures occurred during drilling, with values up to 2.26 mg/m3 in air, 2194 μg/l in urine and 374 μg/l in blood. Furnace operation and cleaning were the tasks with the highest values in metallurgy, peaking up to 3.37 mg/m3. The filling of bottles with mercury by free fall gave values within a range of 1.13–2.43 mg/m3 in air; these values dropped to 0.32–0.83 mg/m3 after introducing a new ventilation system.

Occupational exposure limits for mercury are typically set at between 0.02 and 0.03mg/m3

I found it a little ironic that a work of art created in support of a government dedicated to improve the lot of working people celebrated an industry likely to have been responsible for poisoning the workers in the mine where it was extracted.

Although it seems likely that visitors to the exhibition back in the 1930’s would have been exposed to mercury vapours, given the relatively short period that they would have been in the vicinity their exposure would have been limited and its highly unlikely there would have been a significant risk to their health. However, I’d be more concerned about the staff working in the Spanish Pavilion.

Today the fountain can be seen at the Fundació Joan Miró museum in Barcelona – carefully displayed under glass. Hopefully appropriate measures are taken to protect the workers who have to maintain it from the toxic liquid and vapours.

Mercury fountain

Picture from the Fundació Joan Miró museum website

Silica exposure in the construction industry

One of the most important health risks encountered by construction workers is exposure to respirable crystalline silica dust. Crystalline silica, mainly in the form of quartz, is the main component of most rocks, sands and clays. In the construction industry it can be found in  stone, concrete, aggregates, mortars and other materials.

Respirable particles (smaller than 10 microns in diameter) of crystalline silica,  which are produced during many common activities such as cutting, blasting or drilling granite, sandstone, slate, brick or concrete, penetrate deep down into the lungs where they can cause serious damage. Regular, repeated exposure to respirable crystalline silica can lead to silicosis, a debilitating lung disease, chronic obstructive pulmonary disorders (COPD) and lung cancer. It usually takes many years of exposure to silica dust before these symptoms start.

A couple of weeks ago I was giving a talk to a meeting of safety consultants on the BOHS breathefreely initative and decided to include some discussion on silica exposures in the industry. Unfortunatly no major study has been carried out in the UK. However, there are several detailed papers on exposures in the industry in some comparable countries in the Annals of Occupational Hygiene and other journals, so I was able to include some figures in my talk.

The research has shown that many of the common activities undertaken in the construction industy lead to exposures well in excess of the UK Workplace Exposure Linit of 0.1 mg/m3 for respirable silica – and this isn’t a “safe limit” with an estimated 2.5% of workers exposed to this concentration for only 15 years developing silicosis. Yet for most of the common operations where workers are at risk from exposure to silica, there are control measures available that are usually relatively straight forward to implement.

Heatwave in India – implications for workers

It’s rare that the concerns of ordinary workers makes the news in Europe, but over the past few days there have been reports in the British press about fatalities being caused by a severe heatwave in India.

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(Picture Source; www.commondreams)

According to the Guardian over 2,200 people have died

Andhra Pradesh has been hit the hardest, with 1,636 people dying from the heat over the past month and a half, a government statement said. A further 561 people have died in neighbouring Telangana, said Sada Bhargavi, a state disaster management commissioner.

Environmental conditions have been severe. The Guardian reports

Daytime temperatures hovered between 45C and 47C (113-116 F) in parts of the two states over the weekend, 3-7C (5-12F) above normal, said YK Reddy, a director of the Meteorological Centre in the Telangana state capital of Hyderabad.

The risk from heat stress depends not only on the environmental conditions but also on other factors, particularly

  • workload
  • clothing
  • individual susceptibility

Workers carrying out heavy work for prolonged periods in hot conditions are particularly at risk as they generate significant “internal” heat as well as absorbing it from the environment. Susceptible individuals include the elderly and people who are malnourished. Not surprisingly, then, the majority of the people who have died during the heatwave have been the elderly and manual labourers working outdoors.

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Agricultural workers in India (source Wikipedia)

There are over 3 million construction workers employed in India (the figure is likely to be higher if “informal” workers are included) and many millions more working in agriculture (almost 50% of the workforce). Construction and agriculture are also major industries in other hot countries in the developing world, and there have been reports of numerous heat related illnesses and fatalities linked to manual work in hot conditions in countries such as Qatar, where there has been a boom in construction due to preparations for the 2022 World Cup.

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Construction workers in Qatar (toehk under a Creative Commons Licence via New Internationalist)

The most effective ways to minimise the risks are to prevent exposure or to introduce engineering controls supplemented with work organisation and protective clothing. However engineering controls are impractical in most cases for outdoor workers in the developing world and the so the main way to minimise the risk of workers being adversely affected is to restrict the working time through work:rest regimes or “self pacing” and other administrative /management measures such as providing plenty of cool drinking water. In practice, most employers are unlikely to look favourably on this due to the impact on productivity and profitability. Subsistence farmers are unable to afford the technology available in the developed world (such as air conditioned cabs and automation) that could be applied to reduce their heat exposure and workload and need to work hard for long hours to have a chance of growing enough to survive.

Extreme events like the current heatwave in India are likely to become more frequent in the future due to climate change and it’s not just the developing world that will be affected. The populations of Europe and the United States are also likely to face exposure to heat extremes.

These events present challenges to occupational hygienists. First of all we currently don’t have an adequate method of evaluating the risk in these situations, particularly in the developing countries. The widely used WBGT index has serious limitations and the more complex Predicted Heat Strain Index is far too complex to be used in most situations. So work needs to be done to develop a suitable approach to risk assessment for the developing world. Secondly, given the scale of the problem, there’s a need to find appropriate, effective strategies to reduce and control exposures. Neither are easy tasks. However, some good work has been done on this in countries including India and Abu Dhabi and so the third challenge is persuading employers to adopt the guidance.

Who are Workplace Health Without Borders?

Workplace Health Without Borders (WHWB) is an organisation of occupational hygienists and other occupational health professionals who want to do something about the estimated 2 million people who die every year due to ill health caused by their work, and the countless millions of workers who suffer from work related illnesses. WHWB was established in Canada in 2011 and now has members in countries across the world.

The organisation’s stated mission is to work for a world where none is made ill by their work. A grand aim which will be far from easy to achieve. But WHWB are doing their part in trying to achieve it by working to transfer occupational hygiene expertise, training and resources to developing countries to help them to develop the capacity and local infrastructure to manage and improve health conditions in their workplaces.

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Projects undertaken by WHWB members include

  • established a mentoring programme to provide support, advice and encouragement to occupational hygienists in the developing word
  • establishing a brick plant project to address silica and other hazards in brick plants in Nepal, Pakistan and Tanzania
  • providing technical support on silica dust monitoring in Pakistan
  • facilitated donations of occupational hygiene equipment to Uruguay, Pakistan and Tanzania
  • running the OHTA Basic Principles of Occupational Hygiene course in Tanzania
  • providing training on occupational hygiene to physicians in New Delhi, India
  • sponsored a workshop in India to raise awareness on silica exposure amongst stone crushers

WHWB also organise monthly teleconferences for their members across the globe to share knowledge and experience.

WHWB members attending the recent International Occupational Hygiene Association conference organised a lunchtime meeting to introduce interested delegates to the organisation, its aims, objectives, activities and projects. Over 50 delegates attended the meeting and there was a lot of enthusiasm for what WHWB are doing.

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WHWB co-sponsored the 7th International Control Banding Workshop in partnership with Medgate, which took place at the Conference, and there were also contributions from two WHWB members to the Conference programme. Kevin Hedges from Canada gave an Ignite presentation – Workplace Health Without Borders, Together We Will Make A Difference! – and Dave Zalk from the USA presented a scientific poster entitled Workplace Health Without Borders: Sharing occupational health and hygiene knowledge around the world.

Anyone interested in getting involved can sign up by visiting the WHWB website