Keywords

1.1 Hazard

An informal definition of hazard is simply “something with the potential to cause harm”. In occupational safety, harm manifests itself either by an accident or an occupational illness.

Hazard can be classified by the technical domain it originates from (e.g. mechanical, electrical, chemical, physical, psychosocial hazards). Another way of characterisation is by the vector of the hazard: the potential harm is carried by an equipment (for example machine, tool, experimental apparatus), an activity (for example production, construction, maintenance, dismantling) or a substance, either used in the activity (basic material, catalyser, …) or produced in the process (exhaust gases, dust, …). Numerous hazards exist at the workplaces in an accelerator facility: in the accelerator building or tunnel, in workshops, laboratories and in offices. This book puts the focus on specific hazards at particle accelerators, for example magnetic fields, cryogenic temperatures, and ionising radiation. Industrial hazards present in industry and services impact also the construction, operation, and maintenance of accelerators and one chapter is dedicated to them with references to guidelines in occupational health and safety (OHS).

A useful tool to classify hazards is a hazard list, as reproduced in Annex A. It contains both general hazards from industry and business and specific hazards occurring at accelerator sites.

1.2 Risk

The informal definition of risk is “a measure of the probability of a hazard to cause harm, and of the severity of the consequences.” By reducing risk, one reduces the probability or/and the severity of harmful effects and therefore improves safety.

Measure is often meant in a qualitative sense. Risk can be classified on a coarse scale as low, medium, or high. Such a qualitative judgement is based on a good knowledge of the employed activities, equipment and substances and previous professional experience and remains always subjective.

Quantitative risk assessment makes use of published data on failure rates of components or equipment, accident rates and of models for the behaviour of complex systems. It is a specialist’s domain and is employed in high-hazard industries, such as the chemical and nuclear industries [2].

Often a risk assessment will be situated between the purely qualitative and quantitative and it is up to the professional judgement of the safety specialist and the line management to determine the correct level of assessment.

Risk and hazard are often confounded in colloquial language. People speak of a “high risk” activity, but they usually mean a high hazard activity. While there may exist considerable hazards at a workplace, it is the purpose of occupational safety to reduce and control the risk of these hazards in such a way that workers are not harmed and that the integrity of the public and the environment is preserved.

1.3 Control

The goal of occupational safety is the elimination of hazards and the diminution of risks. One speaks in this context of “control” (or control measure). To control a danger at the workplace, one may progress by elimination, install technical protection measures, equip the worker with personal protections or instruct and train them to avoid the hazards. In many cases, the required control for a given hazard or risk is dictated by law and regulations. Where this is not the case, it is up to line management and occupational safety specialists to agree on the appropriate level of control. It shall reduce risk to a level acceptable by management and workers, without impeding the activity (e.g. the operation of a facility, the conduction of an experiment) beyond the necessary, and without causing incommensurate cost. Choosing and implementing an appropriate level of control is a matter of professional judgement, and as such is based on experience.

The European Union has published a directive, a document that the member states must translate in national law, where a hierarchy of controls is first evoked [1]. The directive stipulates that the employer shall take the measures necessary for the safety and health protection of workers. He or she shall implement these measures based on the following general principles of prevention:

  1. (a)

    avoiding risks.

  2. (b)

    evaluating the risks which cannot be avoided

  3. (c)

    combating the risks at the source

  4. (d)

    adapting the work to the individual, especially as regards the design of work places, the choice of work equipment and the choice of working and production methods, with a view, in particular, to alleviating monotonous work and work at a predetermined work-rate and to reducing their effect on health

  5. (e)

    adapting to technical progress;

  6. (f)

    replacing the dangerous by the non-dangerous or the less dangerous;

  7. (g)

    developing a coherent overall prevention policy which covers technology, organization of work, working conditions, social relationships and the influence of factors related to the working environment;

  8. (h)

    giving collective protective measures priority over individual protective measures;

  9. (i)

    giving appropriate instructions to the workers.

This European directive defines a framework for occupational health and safety, based on a few principles. More than 30 years old, it has shown its effectiveness and has not been revised since. Its principles influence all following directives and laws relating to occupational safety. The U.S. National Institute of occupational safety and health has cast the hierarchy of controls in a more useful way [3]. It gives preference to eliminating or replacing a risk, and to collective protective measures. Personal protective equipment, technical instruction and safety training of the workers is designated as the least effective measure in this hierarchy of controls. It is known that the effectiveness of these measures for the reduction of accidents and occupational illness depends on individual factors and is generally lower than the technical measures listed first.