Issue 9: July 1999

Table of contents

Award winning breath sampler for solvents designed by the Health and Safety Laboratory

A breath sampler, the Bio-VOCTM (designed by scientists at the Health and Safety Laboratory (HSL) together with colleagues from TCM Associates and Markes International Ltd and funded by HSE), has received the Chairman's Choice Prize at The Chemical Engineers' Excellence in Safety and Environment Awards 1999, held in Birmingham in June.

The breath sampler has been designed to enable the biological monitoring of an individual in order to assess their total exposure to solvents from all primary routes (ie via skin absorption, ingestion and inhalation). The Bio-VOC is non-invasive, is relatively inexpensive and can be operated without medically qualified staff in attendance.

The sampler utilises the close relationship between chemical concentrations in the blood and the air found deep down in the lungs. There is rapid exchange between volatile organic compounds, such as solvents, in the blood and air in the lungs across the thin membranes surrounding the lung's alveoli. An equilibrium is reached between solvent levels in the blood and alveolar air and chemical concentrations in the blood can thus be accurately derived by measuring solvent levels in the breath.

An adult exhaling deeply typically breathes out over 4L of air. Only the last 100ml of this air, from the alveolar portion of the lungs, is retained by the sampler.

Once the breath sample has been collected, a screw-in plunger is used to steadily discharge the sample either into a concentrating (sorbent) trap or into a direct read-out instrument. Once sealed in a sorbent tube, the breath sample is stable for transport and analysis. The sampler may be reused by the same individual over the course of a day, but is then discarded.

Conventional biological monitoring methods for solvents rely on the detection and quantification of individual compounds or their metabolites directly in blood or urine samples. Blood measurements are judged to be the best guide to solvent exposure, but the collection of blood samples is invasive, is unpopular with those being tested and requires specially trained staff to take the samples.

Exposure to solvents can cause ill-health. Over seven million UK employees work in industries where some exposure to solvents could occur. The major industrial use of solvents is in the production of paint, coatings, inks and adhesives, which accounts for 60% of all industrial solvent usage.

What's new

Development of methods of estimation of Nox production in large scale chemical fires

(Contractor: HSL)

In implementing the Control of Major Accident Hazards (COMAH) regulations, HSE's Major Hazards Assessment Unit (MHAU) have need to be able to predict the off-site hazards from fires involving chemical warehouses and ammonium nitrate stores. The emission rates of NO and NO2 from such large fires are key issues in COMAH assessments. An area of particular concern is the behaviour of nitrogen-containing compounds in large ventilation-controlled fires. This type of fire has not been included in HSE assessments to date, but there is growing evidence that many steel clad buildings are not sufficiently vented during roof collapse to prevent ventilation-controlled burning.

The aim of this project is to carry out a series of large scale compartment fire tests involving nitrogen-bearing chemicals, especially: ammonium nitrate; isocyanates; polyurethanes; heterocyclic pesticides; acrylonitrile; and acrylics, to investigate the physical consequences of fire exposure to such chemicals eg melting and flowing. From test results, workable methods for estimating NOx production rates and NO/NOx ratios for fires with different levels of ventilation will be developed for incorporation into MHAU's methods for the assessment of fires in chemical warehouses and ammonium nitrate stores.

Improving the safety of workers in the vicinity of mobile plant

(Contractor: IMC Technical Services Ltd)

The use of vehicles in workplaces causes many fatal accidents, often because the driver cannot see the people at risk. Visibility can be restricted by the specialised design of the vehicle, the loads being carried or the manoeuvre being undertaken. Driver aids such as mirrors or CCTV cameras can help but have their limitations, particularly in restricted workplaces such as mines or tunnels. An alternative approach of detecting radio frequency tags worn by workers met with limited success and was vulnerable to surrounding metallic structures as may be found in warehouses or mines. However, the technology of radio tagging has moved on, mainly due to the retail sector's interest in theft prevention, and a reliable system to protect people in the vicinity of mobile plant may now be possible through utilisation of this new technology.

The aim of this work is to review the difficulties encountered by the drivers of a range of mobile plant types in seeing those people at risk from their moving machinery. The work will then review the electronic detection technologies available and will aim to utilise this technology to devise a system to improve the safety of people working in the vicinity of mobile plant. The effectiveness of the detection system will be examined through field trials.

Management of work related violence by SMEs

(Contractor: Poyner Research)

HSE has identified the need for additional guidance for small and medium sized enterprises (SMEs) on violence from members of the public or customers. This has been supported by the Federation of Small Businesses in its report 'Beating Crime in your Business is your Business'. It is intended to identify examples of good practice in the prevention and management of work-related violence in UK SMEs and to establish whether there are examples of joint working that support the theory that work-related violence is best dealt with by firms working together on a community basis.

Comparison of fracture assessment methodologies

(Contractor: HSL)

Over the last 20 years a number of fracture assessment methodologies have been developed. There is increasing reliance on these approaches to justify the safe use of a variety of engineering structures and components. In particular, they are used in the UK to establish the continued fitness for purpose of welded pressure vessels. The aim of this project is to compare the performance of a number of methodologies (such as PD6493, BS7910, R6 and ASME XI) in assessing the structural integrity of pressure vessels and to establish the differences between the them, particularly in relation to the inherent factor of safety

Oxidative stress caused by occupational exposure to metal particles

(Contractor: HSL)

There is growing evidence to implicate the role of metal particulate in the generation of free radicals that may play a central role in the adverse health effects associated with airborne pollutants. In experimental systems it has been observed that iron and cobalt generate toxic oxygen species. Other metal particulates may also contribute to this pathogenic process. More detailed information on the composition of metal particulate from metal working activities and its role in oxidative damage is required in order to properly assess the risks to health from such work activities.

The aim of this project is to investigate the elemental composition of different fractions of metal particulate collected from various metal working activities. The oxidative stress and free radical activity in the samples of metal particulate will be investigated and it is intended to identify specific elemental, biochemical or immunological markers for monitoring exposure to such particulates.

Construction health and safety for the new millennium

(Contractor: Entec UK Ltd)

The construction industry remains the most dangerous landbased industry in which to work. The characteristics of the current culture of industry combine to inhibit the development of effective health and safety management within the industry. Previous HSE-funded research highlighted many problems faced by the industry in the early 1990s and by building on this initial work, and other previous work on the factors which motivate proactive health and safety management, this project aims to review the current approach to the management of health and safety in the UK construction industry. Best practice in other countries will be analysed in order to identify any methodologies or practices of value. The project will also provide clear empirical evidence of the pattern and causes of occupational injuries and ill-health in the construction industry. This research is particularly timely as it will assess the impact that CDM has had upon the industry.

Minimising the psychosocial risks of team working and other flexible ways of working

(Contractor: University of Sheffield)

HSE wishes to obtain information about the potential health effects, both positive and negative, of current working practices - sometimes referred to as 'New Ways of Working'. This research project proposes longitudinal investigations into the effects of two different types of production team working, self-managed team working and lean team working, on employees' mental health. The work will build on existing work already undertaken by the contractor with two industrial partners, a wire making company and a truck manufacturing company, who are introducing team working. It is intended to produce case studies in medical practitioner format to illustrate the potential health effects of the two types of team working to be investigated.

Psychological effects of exposure to organophosphates

(Contractor: University of Birmingham)

HSE has previously funded research to look at the neurobehavioral effects, in humans, of exposure to organophosphorous sheep dip products and to review psychosocial modifiers of non-specific symptoms in occupational and environmental syndromes.

Many of the clinical symptoms associated with exposure to organophosphates are non-specific and this project aims to investigate whether non-specific syndromes are associated with organophosphate exposure and to provide a more complete understanding of the influence of psychosocial modifiers on these chronic syndromes. The work aims to determine whether organophosphate exposure is associated with an increase in symptoms of: anxiety; depression; chronic fatigue and neurological problems.

Behavioural studies on people's attitude to the wearing of hearing protection

(Contractor: Institute of Occupational Medicine)

Under the Noise at Work regulations (1989), employers have a duty to control noise at work as far as is reasonably practicable before issuing hearing protection as a means of safeguarding employees' hearing. In some cases, reducing noise levels at source to acceptable levels may be impracticable, and the protection of employees' hearing must be achieved by other means. Therefore, many workers are required to use hearing protection. Despite the fact that personal protective equipment is an important method of control, there can be a reluctance amongst employees to use it. Employees attitudes to hearing protection may be influenced by a number of factors which can cause under-use. HSE needs to know precisely what factors influence behaviour and attitude in various occupational sectors and what effective approach can be developed to motivate workers and effect changes in attitude. This project will examine how industry has attempted to motivate employees to wear hearing protectors and will test the effectiveness of these methods.

Testing of weathered passive fire protection (PFP) coating systems

(Contractor: HSL)

PFP coating systems are used widely by the oil and gas and chemicals industry in onshore and offshore locations. An offshore survey of PFP systems indicated that there was a lack of evidence on the effects of weathering on such systems and there are similar concerns about PFP materials used onshore.

The aim of this project is to continue an existing programme of real time exposure of test samples coated with an epoxy intumescent PFP system in a marine environment. The weathered samples will be tested to examine the extent of any reduction in their fire resistance against both jet fire and hydrocarbon fire. The extent of corrosion beneath the weathered PFP system will also be determined.

Perceiving and enacting the risks of stress

(Contractor: Sheffield University)

This project is concerned with the psychological processes by which perceptions of psychosocial risks are formed by employees and managers, and the way that these may influence behaviour, health and well-being. The project aims to develop appropriate methods for evaluating perceptions of psychological risks at work. The project will seek to identify the underlying cognitive dimensions of how people perceive the nature, causes and health performance consequences of psychosocial risks and the socio-cultural factors associated with these perceptions. The work will examine how these perceptions might lead to the enactment of risky or beneficial job characteristics by employees or managers and will consider the consequences.

Procedures for dealing with hung-up and windblown trees

(Contractor: The Forestry Commission)

As part of their work, chainsaw operators have to deal with hung-up trees. These occur when a tree being felled does not fall cleanly and becomes caught or hung-up on another standing tree. Hung-up trees can also occur when trees are toppled by the wind ('windblown'). Windblown trees differ from felled trees in that they still have the root plate attached.

Between April 1986 and March 1997, HSE investigated 59 serious accidents involving work with hung-up trees, 12 of which were fatal. Twenty seven of the accidents were directly attributable to operators not following a safe system of work to take down a hung-up tree, and six were attributable to operators working beneath a hung up tree. A further 10 accidents were put down to a lack of training. All these accidents have occurred despite free guidance on safe systems of work for dealing with hung-up trees having been published and available for the past 20 years.

The aim of this project is to improve the use of safe systems of work for chainsaw operators when dealing with hung-up trees.

Guidelines on the use of scientific advice in policy making

Safe? Yes or no?

Drinking alcohol, sunbathing, and eating a hearty English breakfast or a Sunday roast are a few of the everyday activities which are variously claimed to be good or bad for our health. In view of the many conflicting messages which the public receive about what is or is not safe, it is hardly surprising that scepticism about advice from Government scientists is at an all time low.

A number of recent events, notably the BSE/CJD crisis and the controversy over genetically modified foods, have focused attention on the key role that science plays in informing decisions on sensitive issues of public health and safety. These events have highlighted uncertainties and weakened public confidence in the Government's use and presentation of scientific advice. To cite HSE's Director General '...some of our media, and some of the public influenced by our media, learn slow and scare fast'.


To help restore public confidence, the Government's Chief Scientific Adviser, Sir Robert May, published Guidelines in 1997, setting out some key principles applying to the use and presentation of scientific advice in policy making. It is for HSE to determine how these should apply in detail within our area of responsibility. However, typically, they will be relevant in cases where:

In practice, the Guidelines apply to much of HSE's business. They require:

The Guidelines emphasise the need to take independent advice of the highest calibre and to involve some experts from other, not necessarily scientific, disciplines to ensure that the evidence is subjected to a sufficiently questioning set of viewpoints. Non-UK experts should be involved, particularly in cases where other countries have experience of, or are likely to be affected by, the issue under consideration. Departments are required to be proactive in the identification of research needs and to ensure that the process leading to a balanced view is made transparent and consistent across policy areas.

Implementation of the Guidelines

Ministers have agreed a number of measures to ensure the effective implementation of these Guidelines, including that Departments should report annually to the Chief Scientific Adviser. He, in turn, is required to prepare an annual report on implementation across Government, and the first of these was published in August 1998. HSE's procedures were largely consistent with the Guidelines and compared well with those of other Departments. In particular, HSE:

However, Lord Sainsbury has gone on record as saying that the 1999 report will need to be more robust and rigorous than the first. He chairs the Ministerial Science Group, which is overseeing production of the 1999 report. HSE's 1999 implementation report is available to HSE staff on the Intranet (see Board paper B/99/143).

Building Science into Policy

The statement in the Guidelines that policies should be based on the best available scientific advice represents a particular challenge. How does one go about obtaining the best available scientific advice and ensuring that this is consistent and impartial? HSE is leading a research project, in conjunction with several other Departments, to address this question. The project is due to report in July 2000 and the main objective is to identify principles of good practice in engaging scientific experts, including:

The use of scientific advice to inform policy making remains an important and topical issue and two major inquiries are currently in progress. Lord Justice Phillips is leading a high profile inquiry into the BSE/CJD crisis and the House of Commons Select Committee on Science and Technology is investigating the scientific advisory system. The Select Committee is conducting a number of case studies and it has already published reports on GMOs and mobile phones and health. The summary recommendations and conclusions of these reports are available to HSE staff the Chief Scientist Bulletin Board. The two inquiries are both expected to report in Spring 2000.

Future Developments

There are a number of areas where compliance with the Guidelines has been difficult and where further guidance would be useful. These include:

The Government's Chief Scientific Adviser has agreed to review the Guidelines in the light of the Government's 1999 implementation report and HSE workshops, which will include case studies on how the Guidelines have been applied in practice, are planned for later in the year.

Details of some completed projects

Ergonomic study of quarry vehicle access and egress

(Contractor: System Concepts Ltd)

HSE identified that there was a high incidence of accidents and injuries occurring in quarry and landfill environments when operators of large earth-moving vehicles were entering or exiting their vehicles. This research project was commissioned to study the ergonomic issues associated with these problems. The study was designed to investigate a number of risk factors (vehicle design features, environmental characteristics, organisational arrangements and human behaviour) that were believed to be involved. The range of vehicles studied included: dump trucks; bulldozers; front-end loaders; excavators; and graders which were used in environments such as: open-cast coal; china clay; gravel; and landfill sites in a variety of weather conditions. Vehicle design features in operational situations were compared against published guidelines. Individuals' opinions on the contribution of certain factors to the risk of injury were also collected.

From an ergonomic perspective, the following points which had potential to affect human behaviour when entering or exiting a vehicle were identified: design variations between different types and makes of vehicles; dismounting space - as vehicles were often parked very close together; mounting and dismounting technique; footwear - appropriate safety footwear reduced the risk of foot injury or of slips, trips or falls; job design - the number of times in a shift the operator of a vehicle had to access or egress the cab; and the effectiveness and efficiency of vehicle cleaning and maintenance procedures. The factors identified as the most likely to contribute to the risk of accident/injury on entering or exiting a vehicle were: environmental conditions (mud, ice, etc.); unsafe work practices (eg non-3-point hold); lack of proper maintenance of access system; using non-access vehicle parts as a step; high first step distance from the ground; lack of hand/guard rail; poor siting of hand/guard rail; and flexibility of step. The actual measurements of features of the access system on operational vehicles were compared with the design criteria specified in ISO 2867 1994. A number of cases were identified where vehicle designs did not meet the basic dimensions that take into account the human factors criteria that are specified in the standard. From analysis of features associated with vehicle access/egress systems, systems other than suspended steps (such as stairways or inclined ladders with separate handrails) were preferred.

Public perceptions of risk associated with major hazard sites

(Contractor: Staffordshire University Enterprises Ltd)

The overall aim of this research was to help HSE and other Government departments responsible for developing and operating controls over major hazards achieve a better understanding of public perceptions of the risks associated with these sites. It was intended that the research would inform discussions about a number of policy issues related to the regulation of risks at major hazard sites. These included strategies for communication with members of the local public, the requirements for public consultation and participation under the Seveso II Directive and the setting of tolerability criteria for regulatory purposes. The project studied public perceptions around seven different major hazard sites, which varied considerably in scale. The sites were spread across the UK from Tyneside to the Hampshire coast and from North Wales to Yorkshire. The mix of sites presented both toxic and flammable hazards and included three chemical production sites, a major petrochemical complex, an oxygen enrichment and bottling plant, a liquid petroleum gas store and a water treatment works.

The study was based primarily on a series of focus group discussions with local residents living within the consultation or public information zone around each site. The focus group discussions included the use of land use planning scenarios to explore a number of policy issues. Participants also completed an additional exercise (called a Q-sort), designed to elicit their views about the local site. Background research at each site included interviews with site operators, regulators and other key local 'actors' as well as research in local archives.

A full report of this work has been published in HSE's Contract Research Report Series (ref: CRR 194)

Static charging of high resistivity powders

(Contractor: HSL)

A significant number of fires and explosions during the manual addition of powder from drums and sacks to flammable liquids have been attributed to electrostatic discharges. Such events frequently result in serious burns to the operator. To minimise this risk, one of the preferred methods of adding powder to a vessel containing flammable vapours is by pouring the powder down a chute. This method is often employed for the addition of powder to chemical reactor vessels. However, fires still occur. Contact between the powder particles and the chute generates static electricity and this may lead to an incendive discharge. The relevant standards (eg BS 5958) consider the risks of such discharges to be low except for situations where the chute length exceeds 3 metres or high resistivity powders are involved. In an attempt to minimise the amount of charge generation it is common practice to use high density flow and this can lead to the formation of powder plugs. Although the charge density of such plugs is low, when compared to that of powder delivered using modest flow rates, the charge is concentrated. This has led to the suggestion that with medium and high resistivity powders, such plugs may cause electrostatic discharges at the end of the chute.

As part of this project an experimental facility, suitable for dropping up to 50kg loads of powder from a hopper down vertical lengths of chute into a collecting vessel, was designed and constructed. The facility had instrumentation to measure powder charge, electric fields close to the chute exit and electrostatic discharges between the powder and a probe. A powder was used to determine the effects of chute length and diameter, and steady and plug flow, on powder charging and electric fields. The effects of these parameters on the risk of ignition was also assessed. The experimental data produced suggested that when pouring powder into a vessel containing flammable vapour, plug flow was more likely to produce electrostatic discharges from the end of the chute than steady flow and this can increase the risk of ignition. Large powder plugs appeared to acquire less charge than small plugs. The risk of ignition increased if the length of the chute was increased or its diameter was decreased, as these changes increased the levels of powder mass charge density.

All these titles are available as priced publications from HSE Books.

Added to website 25th August 1999

Updated 2021-05-14