Silica exposure in construction

On Monday this week the Health and Safety Executive (HSE) announced that they were launching a two-week inspection blitz focusing on poor conditions likely to lead to ill health on construction sites, a sector in which occupational hygiene controls have, for too long, been overlooked. Last year there were 39 fatal injuries to workers in the construction sector. However, it’s estimated that there are about 100 deaths from occupational disease for every fatal accident in the construction. The HSE have said that their inspectors will be looking in particular at respiratory risks from dusts including silica materials; exposure to other hazardous substances such as cement and lead paint; manual handling, noise and vibration.


A particular risk in construction work is exposure to crystaline silica dust which is present in materials including stone, concrete, aggregates, mortars and other materials. Respirable particles (smaller than 10 microns in diameter and can reach the deepest regions of the lung) of crystalline silica,  which is 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.


Risk of silicosis – Source: HSL 

Most people who develop silicosis  or lung cancer will have been exposed to low amounts of silica dust for 20 years or more without being aware anything was wrong. Unlike safety hazards where the effects are short term, health hazards are often ignored as the symptoms only appear many years after exposure.

Over 500 construction workers are believed to die from exposure to silica dust every year, yet research carried out on behalf of the HSE suggests that employers underestimate worker exposure to silica in the construction industry.


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.

One common task is the cutting of concrete or stone using an angle grinder where extremely high dust concentrations can be generated. Sometimes it’s possible to eliminate the risk entirely by using alternative materials such as plastic kerb stones.  they’re lighter than stone or concrete, they also have other health benefits by reducing musculoskeletal injuries associated with manual handling.

In cases where substitution isn’t possible, using water suppression techniques can be very effective in reducing dust generation at source.


Fitting on-tool extraction onto power tools can also be effective. Research carried out by HSE has shown that a well designed system can reduce exposure by as much as 40%.


Exposure to silica dust can be prevented or controlled if employers recognise the risk and are willing to do something about it. Hopefully the HSE’s “blitz” on construction sites will help to raise awareness and lead to action by employers to address these serious health risks.

Reducing the occupational cancer burden

On Tuesday I was at the Safety and Health Expo at the ExCeL exhibition centre in London Docklands where I was contributing to the BOHS Worker Health Protection Arena.

During the afternoon I spoke with Leslie Rushton of Imperial College London on Occupational cancer – what you need to know. Lesley is is a medical statistician and epidemiologist and led the team that undertook research on behalf of the Health and Safety Executive to produce an updated and detailed estimate of the burden of occupational cancer in Great Britain.  Lesley spoke about the current picture based on the findings of the research while I concentrated on what we can do to prevent and control exposures to those agents responsible for occupational cancer.

The research indicated that about 8,000 cancer deaths and some 13,500 newly diagnosed cancer cases each year could be due to occupational exposures. The main causes that were identified are shown in the following chart.


Occupational cancer deaths by cause in Great Britain, 2005

The research suggests that by 2060 the number of deaths from occupational cancer will have risen by 5,000 to 13,000 a year if we do nothing. So what do we need to do. That was the question that I addressed

The main cause of occupational cancer is asbestos, accounting for almost half of the deaths. The use of asbestos has now been prohibited in Europe, but there remains large amounts within the fabric of buildings constructed before the 1980’s. Providing asbestos containing materials are in good condition the risk to health should be minimal. The potential for exposure arises when they deteriorate or are being removed. Provided the requirements of the Control of Asbestos Regulations and the associated guidance are followed the risk to health should be controlled. But there are still situations where asbestos exposure can occur accidentally or in an uncontrolled manner.

With other carcinogens, the legal position is less specific. Nevertheless, exposure to the carcinogens, and the associated risk, can be controlled by application of good occupational hygiene practices. Central to this is the idea of the “hierarchy of control”.

During my talk I used examples of real life situations to show how adopting good occupational hygiene practices can be effective at minimising the risk.

In many cases, for common industrial processes, solutions are available from Regulators such as the Health and Safety Executive in the UK, OSHA and NIOSH in the USA, and from industry sources. Unfortunately employers, especially small and medium sized countries, don’t know the information is available or how to find it. Trained, experienced, occupational hygienists are well placed to help employers locate the appropriate information to help them control the risks.

However, there are also situations when a ready made solution isn’t available – either because it’s a new process, or new substances are being handled where the hazards are not fully understood (e.g. nanoparticles) or a combination of both of these. In such cases, occupational hygienists have the underlying knowledge and skills to help employers assess the risks and develop solutions.

The future of occupational hygiene?

fortune teller

Last week I was over at the American Industrial Hygiene Conference and Exhibition (AIHce) in San Antonio, Texas. It was my first time at this event and it was a great experience.

This year is the 75th anniversary of the American Industrial Hygiene Association so this was an opportunity to look back on what the organisation has achieved. But they didn’t just rest on their laurels. it’s important to keep an eye on the future too, and this is what they did. Two of the keynotes in particular looked at what is happening in society and the world of Industrial/Occupational hygiene and at developments that are already starting to happen and which are likely to change the way we live and work in the not too distant future.

The first Keynote speaker, on the Monday morning, was Peter Leyden, former Managing Editor at Wired Magazine, CEO of the Reinventors Network and a Silicon Valley entrepreneur. His talk focused on how big technology paradigm shifts are changing our world. First, he took a look at other periods, such as after the Great Depression in the 1930’s, that faced similar changes. He went on to discuss  the major transformations that are taking place in the 21st Century – the digital revolution, the future of video, demographic changes, global shifts, cleaner energy and politics

“To understand the technological changes that are happening around us, we have to put them in an even bigger context. We’re talking about rhythms of national history, or even world history. We are going through a very rare global transformation. From an American perspective, it’s something we’ve gone through only a handful of times,”

He was optimistic that the “brightest minds” will use the available technologies such as new technologies such as bio tech, nano tech and clean tech industries, to bring innovation forward to solve global problems such as climate change.

People will look back on our time period and say, "That’s when the world went digital, that’s when the world went global, and that’s when the world went sustainable" .

Although he didn’t specifically address what was happening in industrial/occupational hygiene, or how these changes would directly affect it,his talk provided an overview of the context in which we are working and a lot of food for thought.

Some of these ideas were developed the next morning in the Keynote by John Howard. He started by looking back at the development of the Industrial Hygiene profession in the USA and it’s achievements. He then went on to discuss the health effects of emerging manufacturing technologies and how technological innovations in sampling practices will change the profession over the next 75 years.

There have been relatively few changes in how occupational hygienists have measured worker exposure to dust, vapours and other hazardous substances since the development of the personal sampling pump by Jerry Sherwood in the UK in 1957. However, Dr Howard suggested that developments in computer technology and miniaturisation could mean that exposure assessment in the near future could involve continuous sensing of the working environment and that it will be possible to directly monitor chemical loads in workers’ bodies and determine how those exposures have altered them. He suggested that personal direct-reading instruments may be developed that would allow workers to control their own exposures, and that occupational hygiene sampling could even evolve to incorporate the use of sensors that continuously send exposure data to a central database.

His predictions echoed a number of the points made by John Cherie at the British Occupational Hygiene Conference in Nottingham in March. He also suggested that relatively cheap sensors and monitors that connect to devices such as mobile phones, tablets and the Internet, that are already being developed (and in some cases are already available) would change the way that sampling and exposure assessment is carried out by occupational hygienists.

These devices may be less accurate than the traditional sampling methods used to assess personal exposures. But this would be more than compensated for by the massive increase in the amount of data.

I have no doubt that there will be major changes in exposure assessment methodologies in the future. The important thing to remember is that occupational hygiene is about protecting worker health and that understanding exposure is an important step towards ensuring that it is controlled and that we achieve a healthy working environment. Anything that improves the validity of what we do is to be welcomed. Exciting time ahead!

Dust Exposure

There are many common industrial processes which cause workers to be exposed to a wide range of toxic and harmful dusts. Although official statistics are hard to come by, John Cherrie of the Institute of Occupational Medicine has estimated that in Great Britain almost 10 million workers are exposed to dust at work.


Handling of powders usually results in significant release of airborne dust, whether this involves the manual emptying of sacks, manual scooping of powders or mechanical transfer of powders and / or into open containers.


​​Any tasks or processes that involve cutting or abrasion of solid materials will generate dust that will become airborne.


Most of these processes are energetic which means that the dust created will form a cloud that can extend over a significant distance.

​Handling friable materials (i.e. substances that break up easily) can result in the formation of a dust cloud that can lead to significant exposure.


​Common friable materials include :

  • Glass and rock wool
  • Refractory ceramic fibre
  • Cotton, flax and other vegetable fibres
  • Wool

​Disturbing dust settled on surfaces will normally result in at least some of it becoming airborne. ​Using compressed air and sweeping are particularly likely to lead to significant exposures and should be avoided .


Sometimes the problem is obvious, and the sensible thing to do is to introduce controls. But in many cases an accurate assessment requires measurement of exposure. In these cases it’s important to have a “benchmark” against which the results can be compared, otherwise they’re meaningless. In Britain we have Workplace Exposure Limits – these are legal standards and where one has been set for a substance exposure must not exceed the limit. With carcinogens, mutagens and substances that can cause allergic asthma, the requirement is tighter – exposure must be reduced as far as practicable below the limit.

Although a significant number of  toxic dusts have been assigned Workplace Exposure Limits many of the dusts which can cause chronic obstructive pulmonary disease or other non-malignant respiratory disease have historically been viewed as ‘low-toxicity dusts’ and haven’t been assigned limits. In Britain, the guidelines for action to reduce airborne exposure to these dusts (10 mg/m3 for inhalable dust and 4 mg/m3  for respirable dust) are now known to be insufficiently protective. The need for a new exposure limit of 1 mg/m3  of respirable dust has been suggested by some authors and limits for dust exposure are currently under review in the EU. 

The Institute of Occupational Medicine, for example, has recommended that “until safe limits are put in place, employers should aim to keep exposure to respirable dust below 1 mg/m3 and inhalable dust below 5 mg/m³”.  The TUC has advised health and safety representatives that they “should try to ensure that employers follow a precautionary standard of 2.5 mg/m³ for inhalable dust … and 1 mg/m³ for respirable dust.” In Germany, the MAK commission has adopted a limit equivalent to 0.3A mg/m3 respirable, where A is the density of the substance in g/cm3. This is equivalent, for example, to 0.8 mg/m³ for many silicate minerals or 1.2 mg/m³ for titanium dioxide. All three bodies therefore regard 1 mg/m³ respirable as a more appropriate guideline than the 4 mg/m3 COSHH trigger.

A commentary in a recent edition of the Annals of Occupational Hygiene discusses the background in more detail.


It’s a controversial issue, but my personal view is that working to 10 mg/m3 and 4 mg/m3 trigger values doesn’t provide adequate protection. Some employers might be concerned that working to lower levels would be costly, but in my experience it’s possible in most cases to reduce exposures to well below the widely used “triggers” by employing standard good practice approaches.

Raising the profile of occupational hygiene

I had a busy couple of days at the beginning of last week trying to raise awareness of occupational hygiene and the profile of BOHS amongst safety specialists. On Monday I travelled over to Northern Ireland for the day (only a short flight from Liverpool) to make a presentation to a meeting of the Northern Ireland Safety Group then on Tuesday I was online delivering a webinar, organised by Barbour and Safety and Health Practitioner, to over 800 participants.

I’ve posted the slides from both talks up on Slideshare. Here’s the presentation from the webinar (with a few additional comments inserted on some of the slides).

My talk in Northern Ireland, where there were close to 100 people at the meeting, focused on Dust – exposure, hazards, assessment and control. I actually started  by asking how many of the audience knew what occupational hygiene was – less than 10% of them, all either health and safety professionals or managers with an interest, raised their hands. This is a common picture. I’ve spoken at Safety Group and IOSH meetings several times in the past and nearly always get a similar response to the question. Clearly there’s a  lot of work needs doing to make safety professionals more aware. We can do that by writing articles in safety journals, by addressing meetings and getting involved in webinars aimed at safety professionals. Hopefully my efforts last week will have made a small contribution to raising the profile of the profession. But there’s a lot more that we need to do.

Suffering for art


I always like to think that “there's more to life than occupational hygiene” and make sure that I find time for other things that I enjoy. So last Saturday we drove over the Pennines to visit the Yorkshire Sculpture Park to take a look at the new art works on display and also to visit their latest exhibition by the American sculptor Ursula von Rydingsvard. She specialises in creating massive abstract sculptures made from 2 x 4 and 4 x 4 beams of Western Red Cedar, carving them and cutting into them with a porable circular saw, assembling them like giant 3d jigsaws

We had booked on a curator's tour of the Ursula von exhibition, held as part of the Museums at Night event. The curator, Sarah Coulton led us on a tour around the rooms in the Underground gallery telling us about how the exhibition was put together, how Ursula works and giving her thoughts on some of the main pieces. It was really interesting to get the curator's perspective and getting insights on the artist's methods and motiivations.

Like most occupational hygienists, I find it difficult to switch off completely. So I couldn't help but wonder about whether the artist had experienced any problems due to exposure to wood dust, as the nature of her work and working methods must mean that she has a regular, significant exposure to wood dust. Western Red Cedar is a potent respiratory sensitiser causing rhinitis and allergic asthma. I found out the answer at the end of the tour when Sarah showed us a photograph of the artist wearing an a powered hood type respirator and told us that she had to wear it as she had become sensitised to the wood dust. In an interview she tells us

I wear respirators, not just the paper masks. And I hate the respirators. There’s a tremendous weight. I’m getting dents in my face, but I have to do it. I’m allergic to cedar because it’s been with me for so long.

Engineering controls, such as local exhaust ventilation would not be practicable. So the use of respiratory protection is the only option – other than avoiding exposure to the dust, and that would mean the end of her career as an artist – unless she changed to working in a different medium, probably not an easy decision for her after making a mark by working in wood in her own unique way. Perhaps she could have avoided developing asthma if she had taken precautions early in her career. But i suspect, that she, like many other workers, was not aware of the risk, or if she was didn't think she would be affected. Asthma is a debilitating condition, and although it is not fatal too often, it affects quality of life. And as a consequence Ursula knows the meaning of “suffering for her art”.




Health and Construction

construction site 2

On Monday this week a worker on a construction site in central London, a former US naval building in Grosvenor Square, died after the building he was working on partially collapsed. At least one other person had to be treated treated for minor injuries.

Accidents on construction sites are all too common. In the period 2012/3 148 people were killed as a result of an accident at work. 39 of these worked in the construction industry. According to statistics from the Health and Safety Executive, although it accounts for only about 5% of the employees in Britain the industry accounts for 27% of fatal injuries to employees and 10% of reported major injuries.

The incident on Monday was a tragic accident that made the headlines. But there are other hazards faced by construction workers that don’t appear in the news. Construction workers can be exposed to various hazardous agents that can have a major impact on their health, the most important including

  • asbestos – although no longer used in Europe it can be present in older buildings and workers can be exposed to asbestos containing dust during refurbishment and demolition work
  • respirable crystalline silica – present in many materials used in construction of buildings
  • diesel exhaust emissions – diesel powered vehicles and equipment are commonly used on construction sites


According to the HSE exposure to these agents has resulted in

  • About 3 700 occupational cancer cases are estimated to arise each year as a result of past exposures in the construction sector;
  • There were an estimated 74 thousand total cases and 31 thousand new cases of work-related ill health during 2012/13
  • over 500 construction workers are believed to die from exposure to silica dust every year.

Construction workers can also be exposed to other chemicals, such as solvents which are present in paints, adhesives and other products. And they can be exposed to physical hazards such as noise, vibration and solar radiation.

The health effects from all these agents don’t appear over night. They are long term, sometimes only appearing many years after first exposure. So it’s easy to ignore them – but they are responsible for considerable more deaths than accidents at work. An article in the Observer last Sunday reported that last year there were 2,500 deaths due to asbestos exposure, 500 due to respirable crystalline silica exposure and 200 from diesel exhaust emissions. So 3,200 deaths due to exposure to hazardous substances compared to 39 due to accidents. A ratio of more than 80 to 1.

And it’s not just about fatalities. Occupational disease also affect quality of life. The HSE has estimated that averaged over the period 2009/10 to 2011/12 74,000 people whose current or most recent job in the last year was in construction, suffered from an illness (longstanding and new cases) which was caused or made worse by this job.

It’s important that employers make strenuous efforts to ensure the safety of their employees while working on construction sites to prevent tragedies like the accident that occurred last Monday. But, in addition, more attention needs to be paid to those health risks. 

BOHS Conference 2014


I’ve just about recovered from attending this year’s BOHS (British Occupational Hygiene Society) Conference that took place in the Hilton Nottingham on Tuesday to Thursday last week. In fact, the conference effectively started on Monday for me as like the last few years, I was running a Diploma exam “taster” day as one of the Professional Development Courses that take place the day before the Conference officially starts.

As usual, there was lots of good interesting Keynotes, workshops and technical sessions. And it was difficult to choose which of the parallel sessions to attend. A record attendance too.

The Conference started with the Warner Lecture which this year was given by Major Phil Ashby. It was quite different from previous years as it wasn’t specifically about occupational hygiene/ Instead he recounted his experiences as a United Nations peacekeeper in Sierra Leone where, together with a small group of comrades, he had to evade capture by rebels by trekking through hostile country. A truly inspirational story.


One of the key points he made was

“There’s no high to be had greater than the thought that you’ve been able to make a difference”

And making a difference is one of the most important challenges facing occupational hygienists today. Over the next 12 months BOHS will be trying to do more to make people more aware of the risks to health faced by workers due to their exposure to dusts, chemicals and other hazardous agents associated with their work, and, most importantly, to persuade them to do more to control them.

Major Ashby was followed by Professor John Cherrie, the recipient of the Society’s prestigious Bedford Medal. His talk, entitled  “Get a Life” discussed the concept of the “exposome” – the exposure profile experienced by an individual over their lifetime. He looked at how new technology including relatively inexpensive sensors and “the Internet of things” can be used to help evaluate exposure in different contexts. The slides from his presentation are available on Slideshare

He raised some interesting points – some of them quite controversial – and certainly provided some food for thought.

I also enjoyed the keynotes by former IOSH President Gerard Hand and Professor Tom Cox of Birkbeck University. Gerard had a very entertaining style relying on humour and personality to make some important points about how to conduct risk assessments in the real world. He particularly stressed the point about getting out into the workplace and talking to the people who do the job. Professor Cox made a very persuasive case for the importance of human factors and psychosocial risks in the workplace.

There was a very comprehensive programme of presentations on current research, case studies and workshops run in parallel sessions. The overall standard was very high and the only problem was that I often wanted to be in more than one place at one time.

And as usual the conference presented a great opportunity for network with delegates from all over the UK and from overseas.

Feeling the Heat

My second presentation at the Health and Wellbeing at Work event last Tuesday focused on managing heat stress in the workplace.

The risks from working in hot environments is often neglected, but there have been a number of fatalities, and some serious, but non-fatal incidents, in the UK recent years due to workers experiencing heat stress and strain.

My presentation covered

  • how the body is affected by heat
  • the factors that need to be considered when assessing the risk (and it’s not just the air temperature)
  • a structured approach to assessing the risk
  • an introduction to how the risks can be controlled.

I’ve uploaded my presentation to Slideshare, and here’s an embedded copy.

Reducing the Burden of Occupational Disease

On Tuesday I was at the NEC in Birmingham attending the “Health and Wellbeing at Work” event. BOHS had a stand in the exhibition but were also running the series of presentations on “Occupational Hygiene, Toxicology and Environmental Health”. I’d been asked to chair the sessions and also made two presentations – one in the morning on Reducing the Burden of Occupational Disease in the UK Today and the second in the afternoon, an introduction to managing heat stress at work.

In the UK, there are currently approximately 12,000 deaths each year due to occupational respiratory diseases. That equates to 32 people per day yet we don’t hear about that on the news. These deaths aren’t dramatic. They’re “slow”. They happen away from the public gaze. And there are other diseases too that aren’t included in these statistics. So the total number of people dying from occupational disease is even greater.

And it’s not just about fatalities. Occupational disease affects quality of life. According to the HSE over a million people believe their health has been affected by their work.


Many of these diseases are caused by the “traditional” agents and processes such as asbestos, silica, isocyanates, welding fume, flour dust and the like. As industry changes new hazards and risks emerge. For example nanoparticles are becoming increasingly common. The hazards and risks are still not fully understood but there are concerns about whether they may cause cardiovascular disease and, in some cases, cancer and other diseases. With environmental concerns recycling is becoming a major industry. Here workers can be exposed to a wide range of hazardous materials such as lead, mercury, cadmium and other toxic metals, and biological agents.

And it’s not just chemical agents. So, for example, exposure to noise can cause deafness and vibration from power tools can damage the nerves and vascular system. These conditions might not be fatal, but can have a significant impact on quality of life.


If we’re to reduce this unacceptable burden od disease action is needed from various parties. The Health and Safety Executive clearly has a role in enforcing the law and providing guidance, but to do that they need to be supported by Government. But the key actions need to be taken at the point where the risks are created – in the workplace. Employers need to recognise where there are potential problems and decide where they may have a significant risk so that they can introduce appropriate measures to control exposure. This is where occupational hygienists come into the picture.

In some cases there’s already a solution, but employers may not be aware of it. An experienced occupational hygienist will be, however and can draw it to the employer’s attention and help them to implement it. With new and more novel risks occupational hygienists have the skills and experience to help devise a solution.

But to be successful, different groups need to make a serious commitment to take action and work together. And BOHS and occupational hygienists have an important role to play in this.