Safe System of Work: A formal procedure designed to eliminate or control hazards which includes the physical layout of the job, the sequence of operations, provision of tools and equipment and the issuance of relevant notices, warnings and specific instructions. A planned procedure to prevent harm to personnel.
		Safety: The minimisation of contact between a person and hazard, predominantly concerned with the prevention of physical harm to an individual.
		Safety Assurance: The concept that safety can be managed in a similar way to quality assurance, by following management systems designed to eliminate accidents. The concept was at its height in the mid 1980s but has been largely superseded by HSG65 and BS8800.
		Safety Audit: A systematic and critical examination of each area of a company’s activity, the object of which is to reduce accidents and minimise loss. The process not only looks for the presence of a safety related activity but also how well it is carried out.
		Safety Case: A systematic and often quantified model of a system or installation which demonstrates that it meets specified safety criteria. It is a legal requirement in certain industries such as offshore workings, nuclear power generation and the operation of railways.
		Safety Climate: The environment in which a safety culture thrives or otherwise, indicated by the number of accidents and failures, attitudes of management, presence of policies and procedures etc.
		Safety Culture1: The set of norms, roles, beliefs and attitudes, and the social and technical practices within an organisation, which are concerned with minimising exposure to hazard and risk. (John Gilbertson).
		Safety Culture2: “The safety culture of an organisation is the product of individual and group values, attitudes, perceptions, competencies, and patterns of behaviour that determine the commitment to, and the style and proficiency of, an organisation’s health and safety management. Organisations with a positive safety culture are characterised by communications founded on mutual trust, by shared perceptions of the importance of safety and by confidence in the efficacy of preventative measures”. (HSC’s Advisory committee on the Safety of Nuclear Installations).
		Safety Data Sheet: Information sheet relating to a chemical supplied with intention of being used at work. Required by virtue of CHIP the information to be included is specified in the schedule to the regulations.
		Safety Factor: See Factor of Safety.
		Safety Inspection: An examination of a work area against a pre-determined checklist which seeks to identify substandard conditions and acts.
		Safety Management System: An integrated combination of policies, procedures, codes and rules which dictate how the company responds to the safety demands placed upon it. A framework for management decision making which helps to clarify any areas of ambiguity.
		Safety Phrase: A concept introduced by the Chemicals (Hazard, Information and Packaging for Supply) Regulations. Chemicals requiring specified safety precautions must be labelled with the relevant safety information (phrase) eg S20: avoid contact with skin.
		Safety Policy: A fundamental component of an organisations OH&S management system established by statute (HASAWA s2(3)). Three main elements include a statement of intent, organisational means for implementation, and the arrangements made for OH&S in the workplace. MHSWR added the requirement to include arrangements for assessing and recording significant risks.
		Safety Practitioner: Evolutionary title now given to one who practises the discipline of occupational safety and health. A practitioner is one who can identify symptoms of problems in an organisation; determine the cause; and deliver a remedy (John Gilbertson).
		Safety Representative: A worker representative appointed by a recognised trades union in a workplace who has rights to perform statutory functions such as inspections, accident investigation, attend safety committee etc (Safety Representatives and Safety Committees Regulations). See also Representative of Employee Safety.
		Safety Sampling: A routine, repeatable technique used to measure the accident potential of a particular area against a pre-determined list of unacceptable deviations from standards.
		Safety Survey: A detailed examination of critical areas of operation or particular operations or departments within an organisation eg machinery guarding survey, fire precautions survey.
		Safety Tour: An impromptu, unscheduled examination of a work area to review a particular subject or issue. Undertaken by, for example, safety committee at an appropriate juncture or a supervisor or manager in response to a problem etc.
		Sampling Head: The working end of a sampling train which holds the sample collection medium. See Open Face Head, Protected Face Head, Cyclone Head, Solid Adsorber and Liquid Adsorber.
		Sampling Train: The set of equipment used for personal sampling for airborne concentrations of substances hazardous to health, comprising a filter, sampling head, flexible tubing and a portable pump.
		Sampling1: See Safety Sampling.
		Sampling2+A889: The measurement and analysis of general and personal exposure to hazardous substances in order to evaluate compliance with occupational exposure limits.
		Scaffold: A temporary working platform constructed of sound, strong materials, usually metal tubes. See Putlog Scaffold, Independent Tied Scaffold and Birdcage Scaffold.
		Scaffold Tie: A method of fixing a scaffold to a permanent or existing structure. See Reveal Tie, Through Tie and Ring Tie.
		Scaffold Tower: A portable scaffold structure comprising of prefabricated sections which can be easily transported and fitted together at a worksite. They are frequently fitted with castor wheels for ease of movement in place.
		Scientific Management: A school of management developed between 1910 and 1940 which was based upon a logical and rational approach with an emphasis on making people work more efficiently by breaking down large tasks into smaller components and clearly defining how the job should be done and how long it should take. See Taylor.
		Scintillation Counter: A device containing material that emits light flashes when exposed to ionising radiation. The flashes are converted to electric pulses and counted. The number of pulses is related to dose.
		Second Action Level: A point at which an employer must take action to reduce an employees exposure to noise by means other than personal protection where reasonably practicable. A daily personal noise exposure of greater than or equal to 90dB(A) (at time of going to print).[3] See also First Action Level and Peak Action Level.
		Secondary Explosion: An explosion of dust layers and deposits which have been disturbed by a smaller primary explosion.
		Secondary Group: A large, relatively formal group such as a department or section within an organisation. Role relationships are predominant and the group functions impersonally at a fairly instrumental level.
		Secondary Irritant: A substance whose reaction on the skin occurs some time after repeated exposure and occasionally the effects may be observed on parts of the body other than those originally exposed. Condition is also known as allergic dermatitis.
		Selectivity: A function of human perceptual processing which either consciously or unconsciously allows the brain to recognise signals or data from the environment. We ‘see’, ‘hear’ etc what we want to.
		Self Actualisation: A state of self fulfilment which emerges when lower order needs have been satisfied, described by Maslow as a degree of autonomy and choice about self and a release of potential.
		Self Regulation: Modern trend in safety legislation which sets standards and objectives and leaves it to the duty holder to determine how best to achieve them.
		Semiconductor Chemisorption Detector: A direct reading instrument for organic gases in which the contaminant is chemisorbed onto a metal oxide surface causing a change in the electrical resistance of the semiconductor material. The change in resistance is proportional to the concentration of gas.
		Sensitiser: See Respiratory Sensitiser and Allergic Dermatitis.
		Sensory Illusion: A type of error experienced through sensory perception when information received confuses sensory receptors eg very cold substances appear hot, glass doors appear invisible because of lighting.
		SEPA: Scottish Environmental Protection Agency.
		Severity Potential: The worst injury, illness or damage that could result from an accident.
		Severity Rate (SR): Statistic used to illustrate the average number of working days lost due to accidents for every 100,000 hours worked. SR = Total Number of days lost x 100,000 Total person hours worked Note: that multiplier may vary for different organisations, agencies and countries, use caution when making comparisons.
		SFAIRP: So far as is reasonably practicable. See Reasonably Practicable.
		Shackles: A device in the shape of a bow or the letter D incorporating a removable bolt which can be attached to an eye bolt or part of a fixture to create a lifting point.
		Short Term Exposure Limit: The 15 minute TWA exposure which should not be exceeded at any time during a work day even if the daily TWA is not exceeded. It is designed to take into account the acute effects of short term high exposure to chemicals.
		Sievert: See Effective Dose.
		Silencer: See Reactive Silencer and Absorptive Silencers.
		Silicon Diode: A device made of a silicon compound in which current flows when exposed to ionising radiation. The current is converted to electrical pulses and counted. The number of pulses is related to dose.
		Silicosis: A prescribed disease of the lungs characterised by the development of fibrotic modules around the embedded Silica dust. The disease gradually develops as large coalescent nodules reduce lung function and cause breathing difficulties.
		Simple Asphyxiant: A substance which causes suffocation by reducing the amount of oxygen available in the atmosphere for gas transfer in the lungs; examples include nitrogen and carbon dioxide. See Chemical Asphyxiant.
		Single European Act: In 1986, a European Union Treaty which set out the conditions and mechanisms for European integration by the end of year 1992.
		Situational Violation: A violation where the rules are broken due to pressure to complete the task, or because it is difficult to comply with the rule in the circumstances, e.g. a scaffolder not using a harness because there is no where to secure it at that time. See Routine Violation and Exceptional Violation.
		Six Pack: Reference to six sets of regulations brought into force by the end of 1992 to meet targets for a particular phase of European unification. The expression is no longer of significance due to the many changes which have taken place since their introduction.
		Skill-based Behaviour: Is displayed in familiar situations where the operator recognises a signal, understands that this requires a normal routine and therefore executes a well learned and practised response more or less automatically. See Skill-based Errors.
		Skill-based Errors: May be considered as intention (of outcome) being correct but the action (motor-response) is executed badly. Examples include pressing the wrong button on a telephone or computer keyboard where the consequences are relatively trivial - however, pressing the accelerator instead of the (intended) brake in a driving emergency may be a more costly slip.
		Skin Ulceration: The result of exposure to hexavalent chromium (eg: cement burns and chrome holes) and, in extreme form, in perforation of the nasal septum (work in plating shops).
		Sling: Flexible equipment constructed from chain, fibre rope or wire rope used to lash or secure loads to lifting devices.
		Societal Risk: Term used when determining the tolerability of risk to define the chance of a large accident in a hazardous industrial installation causing a defined number of deaths or injuries. See Individual Risk.
		Sociogram: A diagrammatic or mapping technique used to display the interpersonal preferences of members of a group ie. who likes who, who works best with…, who is the preferred leader etc?
		Sociology: A branch of the behavioural sciences concerned with theories and predictions about complex social groups, the differences between them and structural influences upon them.
		Socio-Technical System: Concept of an organisation which illustrates the interdependency of its technical components (task and technology) and its social components (structure and people).
		Soft System: A system comprising of mainly abstract things, thus strongly dependant upon the perceptions of the observer.
		Sole Plates: Long boards placed under the base plates of standards whose purpose is to evenly distribute the weight of the scaffold.
		Solid Adsorber : Sampling head comprising a glass tube containing an adsorbent material such as powdered charcoal or silicon gel. The material effectively adsorbs vapours from the air passing over it and after sampling the tube is sealed and sent for analysis.
		Solvent Scrubbing: Alternative name for Liquid Adsorption.
		Sound: Any pressure variation (in air, water or other medium) which is detectable by the human ear.
		Sound Power Level: A measure of the total acoustic power produced at the noise source.
		Sound Pressure Level: The basic measure of noise, at a distance from the noise source, expressed in decibels usually measured with a frequency weighting eg dB(A).
		Special Damages: Compensation consisting of calculable damages generally prior to a case being heard which include legal and medical expenses, loss of earnings and costs of adjustments to lifestyle.
		Specific Gravity: The weight of a liquid relative to water, values of less than one indicate that a material will float on water.
		Spectrophotometry: A technique used for measuring or comparing the absorbencies of solutions, gases or vapours. A monochromatic beam of light is passed through a sample which may transmit or absorb or scatter the light in some way. The remaining light is measured as an output by a photometer.
		SPL: Sound Pressure Level.
		Spontaneous Combustion: A condition manifesting in certain materials (especially organic materials) which react with oxygen at room temperature and produce heat. If the fuel is a good insulator the heat generated builds up until the autoignition temperature is reached and true combustion commences.
		Spontaneous IgnitionTemperature: See Autoignition Temperature.
		Spurios Trip: A fault which causes a system to activate when not required.
		Stability: Relating to fire resisting properties – the ability of a structure to resist collapse for a specified period of time when exposed to fire.
		Stack Effect: Method of ventilating a building using the principles of convection. Heated air inside the building is discharged through a chimney (stack) and cool outside air is drawn in through windows or vents to replace it.
		Stain Tube Detector: A proprietary device comprising a chemical reagent housed in a glass tube. Air is drawn through the tube by means of a pump and any contaminant in the atmosphere causes the reagent to change colour. The length of colour stain in the tube is proportional to the concentration of contaminant in the atmosphere.
		Standard: The long upright metal poles which constitute the vertical structure of a scaffold.
		Standby System: A reliability engineering technique involving the installation of a secondary unit which activates upon the failure of the primary unit.
		Static Pressure: The difference between the absolute pressure at a point in an airstream or pressurised chamber and the absolute pressure at ambient temperature (ie the bursting pressure).
		Statute Law: A source of law in the form of a codified, written structure laying down formal rules to be observed by those to whom the statute is expressly or implicitly addressed. The laws are interpreted by the courts and such interpretations are binding on lower courts. Breaches of statute are normally, but not always, concerned with criminal law. For instance the Occupier’s Liability Acts give rights in civil law only. A breach of statutory duty may also give rise to civil liability unless the statute specifically excludes it.
		Statutory Duty: Duty placed upon an individual by an Act of Parliament or Regulation.
		Statutory Instrument (SI): Official description given to subsidiary or delegated legislation which puts in effect specific duties which are described in general terms in the parent Act, eg SI 1992 no 3073 The Supply of Machinery (Safety) Regulations 1992.
		Statutory Nuisance: One specified by statute for which there are specified courses of action by either an individual or an enforcement authority.
		STEL: Short term exposure limit.
		Stereotype: An expectation held by most of the population of either a person or situation.
		Stimulus Response Learning: Lower order state of learning in which the learner exhibits behaviour directly related to a specific stimulus. See Classical Conditioning and Operant Conditioning.
		Stipendiary Magistrate: A Magistrate who is a qualified barrister or solicitor appointed to try cases in the Magistrates Court. Such persons are paid (a stipend) for their services and have the equivalent power of three lay magistrates.
		Stoichiometric Mixture: That mixture of fuel and oxidising agent (vapour/gas) which will combust completely. For hydrocarbon fuels in air, that mixture which combusts completely to produce carbon dioxide and water. There will be no fuel or oxygen remaining eg CH4+ + 2O2 ? CO2 + 2H2O is a stoichiometric mixture; 1 part methane to 2 parts oxygen.
		Stokes Behaviour: The streamlined flow of smaller particles whose resistance in air is proportional to the diameter of the particle and its velocity.
		Strain1: Is the measure of the change in shape (or size) of a material when a force is applied in tension or compression. Strain = Change in length Original length
		Strain2: The physical or psychological manifestation of the effects of being exposed to stress. Symptoms may include behaviour changes or changes in personality.
		Stress1: Mechanical stress is the measure of the force applied to a body or component divided by the area over which the force is applied. Stress = Force Cross Sectional Area
		Stress2: An event or situation which places increased demand upon a person’s mental or emotional resources. Sources of stress may be occupational or domestic/social each has the ability to be either stimulating or harmful. See Strain2.
		Strict Liability: Liability for an occurrence which does not require proof of mens rea only the actus reus needs be shown. The burden of proof rests with the defendant.
		Stroboscopic Effects: A phenomenon more usually associated with older lighting systems where the frequency of oscillations in light output is a multiple of the frequency of the movement of machinery. The visual illusion of stillness is created.
		Subjective Measures: Performance measures that are (or may be) influenced by the observer ie personal judgement may be subject to experience, knowledge or other influence.
		Subordinate Legislation: See Regulation.
		Substance Hazardous to Health: Defined by regulations as one which is very toxic, toxic, irritant, harmful or corrosive; carcinogens; dust of any kind in substantial concentrations; micro-organisms; and anything similar to the above.
		Substandard Act: A term offered by Frank Bird in an attempt to objectify and define a measurable component of an unsafe act.
		Substandard Condition: A term offered by Frank Bird in an attempt to objectify and define a measurable component of an unsafe condition.
		Substitution: A control measure employed when elimination is impossible which substitutes a hazardous material for a less hazardous one, to substitute the state or form of the same substance for one which gives rise to less exposure.
		Sub-system: An identifiable element of a system which has all the characteristics of a system in its own right.
		Sue: The act of pursuing a legal claim in civil law.
		Suitable and Sufficient: Often used concept in goal setting legislation which will ultimately be for the courts to decide. Broken down the word suitable suggests appropriate (in all the circumstances) for the purpose; and sufficient suggests of the right quantity, or going into enough detail to achieve compliance. Suitable and sufficient work equipment would imply the provision of the right tools, of the right quality, in sufficient quantities to enable work to be carried out safely.
		Summary Dismissal: A situation where the employer terminates the employee’s contract of employment without notice. In order to justify the use of this tactic the employee must be in breach of an important express or implied term of the contract such as gross misconduct.
		Summary Offence: Less serious criminal offence normally tried in the Magistrates Court. Penalties are limited by statute (see s33 HASAWA).
		Survey: See Safety Survey.
		Susceptibility: The predisposition of a person to suffer a particular effect from exposure to a workplace condition or substance.
		Synergy: Interaction between two or more components of a system which produces an output greater than that anticipated from the single addition of the individual outputs.
		System: An assembly of component parts connected together in an organised way for the purpose of doing something. The components are affected by being in the system and the behaviour of the system changes if they leave it. See Hard System, Soft System, Open System and Closed System.
		System (electrical): See Electrical System.
		Systematic: An organised, structured way of doing something.
		Systemic: An analytical or investigative approach which considers a system as a whole with emergent properties.
		Systemic Effects (health): The action of a chemical or biological agent at a site remote from the point of contact after the substance has been absorbed.

Disclaimer:
Whilst every effort has been made to ensure the accuracy of the information contained in this book opinions may vary regarding some concepts. The Key Consultancy Ltd and Safety and Health Practitioner accept no responsibility for any loss arising from reliance on this content and readers should take steps to verify interpretations to their own satisfaction if there is doubt.