Stemming from ethical motivations, legal standards were introduced in the beginning of theBasic Constitutional Law of the Federal Republic of Germany. Article 2 (2) of theConstitution of the Federal Republic of Germany says:

“Everyone has the right to life and physical integrity…”

Aspects of occupational health and safety are also considered in the first lecture in thecore-definition of industriual engineering:

Working persons should

- come across “damage-free, executable, tolerable, and disturbance-free workconditions”

- “see standards of social appropriateness according to work content, work task, workenvironment and renumeration as being fulfilled”.

- “be able to develop room for maneuver, acquire skills, and retain and developindividual personality in cooperation with others”.

The estimation of the production downtime due to sick days, monetarily quantifiedthrough the variables labor costs and loss of gross added value, from an economic pointof view indicates a prevention potential and a possible potential benefit. Besides the dataof sick certificates of compulsory insured and voluntarily insured of the statutory healthinsurance there are also data of the economic total account of the Federal StatisticalOffice that flow into these estimations of economic downtime due to the inability to work. Itis assumed that the labor costs of the employees and the gross added value of employedpersons are transferable to the data of the aforementioned insured persons of thestatutory health insurance. Furthermore, it is to be considered that the data of sick daysused here does not contain all the causes of disability, but only those which have beenreported to the health insurance via a sick certificate from a physician. Therefore, thereare underestimations in the field of short-time inability to work. In addition, at this point itshould be mentioned that through necessary projection and rounded data, differences inthe column-summation and rounding errors are partly not avoidable. With an averagelength of 15 sick days per employee, 567,7 million sick days result for the year 2013.Based on this volume of inability to work, the Federal Institute for Occupational Healthand Safety estimates the economical production downtimes to all in all 59 Mrd. Euros (1.6million lost working years * 36,875€ average employee remuneration) and the loss ofgross added value to 103 Mrd. Euros (1.6 million lost working years * 64.375 € averagegross added value).

(Source: Bundesanstalt für Arbeitsschutz und Arbeitsmedizin 2015; Stand der Statistik:2013 und im Vergleich 2012)

In Article 137 (so-called EU social directives) of the treaty of Amsterdam to change thetreaty of the EU (so-called EG-Vertrag, EGV), employee safety is named as a commongoal involving the attainment of minimum requirements for the safety and health ofemployees.

As one of the important directives for occupational safety, the occupational health andsafety framework directive (89/391/EWG) follows, which, in connection to severalindividual directives for work materials and tools, work situations and physical impacts,must be converted into a national right to the same extent.

Therefore, it follows that the national legislator in his/her sovereignty is able to makeadditional regulations.

In production safety however, there is a difference: According to Art. 95 EGV, aharmonization of technical requirements and standards related to the introduction oftechnical work tools, materials and preparations is required. The individual regulationsbased on this (e.g. regarding pressure tanks, hazardous materials, emissions, etc.) arebinding and are to be put 1:1 with the national legislation.

For operational practice it is meaningful for regulations for occupational health and safetyto be frequently used in connection with regulations for production safety andenvironmental safety.

The Occupational Health & Safety law can be applied to many legal areas: in the privateoccupational health & safety law the rights and obligations of the individual employeesand the employer are defined based on of the labor agreement law (§§ 618, 619 BGB, §62 HGB, individual occupational health & safety law), that is, for the employees andemployer based on the right of codetermination (BetrVG, collective occupational health &safety law).

In public occupational health & safety legislation there is the national occupational health& safety law, based on “article law occupational health & safety” (law of implementation ofthe EU directive occupational health & safety and additional occupational health & safetydirectives), as well as resulting law and law amendments including various legalordinances.

Statutory ordinances are concretized via technical regulations in line with the definition ofsafety goals, e.g., TRBS – technical regulations for occupational safety, TRGS – technicalregulations for hazardous substances, RAB – regulations for occupational health & safetyon construction sites. These regulations are formulated by technical committees and thenannounced by the Federal Ministry of Economics and Labor.

In addition, the state sets the competencies of the intitutions for statuatory accidentinsurance (in German: “gesetzliche Unfallversicherung”) in the Social Security Code VII,i.e. the public commercial and agricultural statuatory accident insurance and preventions(in German: “Berufsgenossenschaften”, BGs) and the occupational accident insurancefunds of the public sector (in German: “Unfallversicherungsträger der öffentlichen Hand”)who practice an autonomous occupational health and safety right.

The statuatory accident insurance and preventions (BGs) issues binding accidentprevention rules for its member businesses in the form of trade association regulationswhich are to be applied practically in the firms through trade association rules andprinciples. The (autonomous) regulations of accident insurance carriers are, for the most

part, replaced by (national) technical rules during the course of the conception of theGerman occupational health & safety legislation due to the EU harmonization

At the same time, DIN, DIN EN standards and recommendations of unions (VDI, VDE,etc.) supplement the technical body of legislation. These bodies of legislation are notlegally binding until referenced within legal ordinances, technical regulations or accidentprevention rules (Lehder & Skiba, 2005; Pieper & Vorath, 2005).

(Arbeitsschutzgesetz, ArbSchG)

Act on the Implementation of Measures of Occupational Safety and Health to Encourage Improvements in the Safety and Health Protection of Workers at Work

Basic duties of the employer

Measures of occupational safety are part of the basic duties of the employer (and of the area of responsibility of future engineers / employers)

The employer has a duty to examine the effectiveness of the measures of occupational safety

Interdisciplinarity / cross-interface management systems

Occupational safety as management task is to be regarded in the context of further management systems.

In the quality management the PDCA-cycle (Plan, Do, Check, Act) according to Demming explicitly includes the control of the measures as a systematic approach for continuous improvement.

In the lean management the idea of the gemba walk or Management by Walking Around is put into operational practice. At this, the management obtains an overview directly where the action takes place. With regular inspections of the manufacturing, mounting and logistics systems by the management (next to the observation of optimization possibilities), improvement possibilities in the occupational safety can be identified. Thus, a regular inspection can serve for the examination of the effectiveness of measures of occupational safety.

According to Diekershoff (1983), occupational safety is understood as all measures whichare focused on protecting the life and health of employed people from harmful influencesin the context of their occupation, to preserve them from impairment and to generate theirwell-being in the company.

The aim of occupational safety especially is to create a safe working environment, itspurpose the preservation from physical and psychological integrity of the workers andtherefore the long-term maintenance of the labor force.

Occupational safety is the safety of workers at work, thus the control and minimization ofrisks for their safety and health. It is therefore part of the occupational safety in themeaning of the Occupational Safety Act, which requires measures for the prevention ofaccidents at work or work-related health risks, including measures regarding humaneworking conditions (Schliephacke, 2008).

Risk: the risk associated with a specific technical procedure or condition is described by aprobability measure which takes into account the probability of an occurrence of an eventthat could lead to damage and the expected extent of resulting damage (negative utility).

Acceptable risk: acceptable risk is the greatest still justifiable risk of a particular technicalprocedure or condition at which no further improvements need to be made.

The ISO/IEC-Guide 51:1999 which determines these terms at the international level, usesthe term tolerable risk as it is the risk that is, based on the common values of the society,accepted in a given context.

The acceptable risk separates the complementary areas of high and low damageprobability. These are often described simplified as the areas of danger and safety. Thedanger in this sense is a circumstance at which the existing risk, this means at which afrequency and effect of the to be feared direct and indirect damages of all kind for life andhealth, exceeds an acceptable risk (Neudörfer 2011).

Damage: damage of legal goods due to a specific technical procedure or condition.

Danger: circumstance in which risk is greater than the acceptable risk.

Safety: circumstance in which risk is not greater than the acceptable risk.

Safety-related regulation: statements about technical values and measures as well asbehavior instructions which are to ensure, depending on the particular technical concept,that the threshold risk is not passed.

Protection: limiting of risk through measures that describe either the occurrence frequencyor the extent of damage, or both.

The illustration shows the relations between component and functional reliability on theone hand, and between operating, occupational and environmental safety on the otherhand.

The safety reviews basically refer to the following domains:

- The environmental safety deals with the limitation of damages in the environment oftechnical systems.

- The operating security relates to the control and minimization of risks for the workers, ifnecessary also while using technical systems outside the workplace, e. g. in sports orleisure time.

- The occupational security includes the limitation of risks while operating technicalsystems, so that the systems, as well as its immediate environment (permanentestablishment, neighboring systems) do not get damaged.

For the operating, occupational and environmental security the reliability of componentsand their interaction in the technical system while fulfilling their functions, thus thefunctional reliability of the machine or a system designed for protective purpose, is ofcrucial importance.

Without this condition of component or functional reliability the operating, occupationaland environmental security could not be achieved.

Therefore, for the engineer all of the domains are closely related with regard to theconcept and the design. Safety engineering always needs to pay its attention equally toall of the impact areas (Pahl 2005).

The component reliability only describes the fatigue strength and maximum load set bythe material properties of the individual components. Its use in component groups withadditional individual components thus remains ignored.

For component reliability it is important to know the characteristics of the material used interms of its fatigue strength, plasticity and/or brittleness, elasticity, etc. Material samplesare then tension tested in which the sample is mounted into a tension testing machinewith a known outlet cross-section A0 and strained with a tensile force of F.

To get a measurement curve which is only dependent on the type and structure of thetested material, instead of the geometric measurements of the sample, reduced units areused – i.e., the change in length ∆L is based on the initial length L0 and the force F isbased on the cross sectional area A0 of the sample.

The reduced units are called elongation and stress . The curve is called the Stress-Strain-Diagram. P is the proportional limit stress until that stresses and elongations areproportional and therefore Hooke’s Law applies. E is the elastic limit that marks the endof the linear-elastic material behavior and therefore describes the inserting plasticdeformation.

The yield point Ren is the stress, at which the stress-elongation-diagram, under theoccurrence of a noticeable steady elongation, shows a reversal of the gradient.

The ultimate stress Rm (fracture strength) is the highest stress the sample can bear.When exceeding the ultimate stress, the sample constricts significantly at furtherelongation.

A component from a ductile material can either fail or become inoperative due to plasticdeformation or due to break. Thus the allowable stress zul can be calculated as follows(Läpple 2011, Böge 2011):

For components of a brittle material respectively at brittle material behavior only a breakcan make a failure possible. The allowable stress zul can only be determined via fracturestrength Rm, with a correspondingly higher certainty:

The fatigue behavior of materials or components (component Wöhler Test) is determinedwith the Wöhler Test. It is named after August Wöhler, who carried out the firstmethodological fatigue strength tests between 1858 and 1870 to approach the endurancelimit of steel. Every Wöhler Test is performed with a constant medium stress m, while thestress amplitude a is varied.

Then, it is calculated how long a sample with a diameter of d=10 mm withstands with m

and the effecting a, this means how many numbers of load cycles it endures.

The number of load cycles N1 at which the break occurs delivers, together with the stressamplitude 1, exactly one point on the Wöhler line.

Underneath the fatigue strength zdW a component in principle can endure any number ofload cycles with the nominal stress amplitude a. Any stress above the fatigue strengthwill cause a failure after a certain number of load cycles.

According to the illustration three characteristics for steel result:

- characteristic a - statical steadiness

Characterization through the statical steadyness, e. g. fatigue strengh Rm at tensilestress. According characteristic values here apply for the other possible types of stresslike bending or torsion.

- characteristic b - cycle fatigue

Here the stress amplitude is higher than zdW and lower than the tensile strength Rm.The material can only endure this stress for a limited time respectively number of loadcycles.

- characteristic c - endurance limit

This is the boundary stress that can only just be endured arbitrarily without a breakoccurring. (Schlecht 2006)

Functions acquire the individual components in relation to their environment and theresulting requirements. Functional reliability describes the load bearing capacity of anelement depending on its application to particular component, their interaction, and theremaining safety.

Often it is not possible to determine the suitability of a bearing selected for a certainapplication case through the testing of a sufficient number of bearings in this applicationcase.

Though, lifetime durability is a fundamental information for the suitability. A reliablecalculation of the lifetime duration therefore is seen as an appropriate and suitablereplacement for the suitability test.

The lifetime duration of a bearing is defined as the number of revolutions a bearing ring orplate performs in relation to the other bearing ring or plate, before the first sign of fatigueis seen at one of the rings or plates or at a rolling element.

With enough lubrication and cleanliness and a medium to high stress, the lifetimeduration of the bearing ends due to fatigue damages that proceed from the inside of thematerial to the tread (chipping of material particles, peeling and pitting at lubrication).

The nominal lifetime duration L10 is the with a 90% reliability achievable mathematicallifetime duration for the bearings that were manufactured from today generally used high-quality material with proven production quality and that run under normal operatingconditions.

Therefore it is permitted that up to 10% of the installed bearing break down beforereaching the lifetime duration value.

The calculation of the nominal duration for any load is carried out over the relation C/P ofthe dynamic basic load rating to the real equivalent dynamic stress, exponentiated with p(according to the standard, p is 3 for ball bearings and 10/3 for roller bearings, whereas

certain deviations from an even stress distribution along the line of contact are alreadytaken into account; at ideal stress distribution p is 4). The nominal lifetime duration veryoften serves as a dimensionless quantity (comparison of the lifetime duration of bearingsrespectively empirical value for the necessary nominal lifetime duration in differentapplications) (Steinhilper 2012).

Occupational safety describes the safety resulting from all the elements working togetherand their prevailing functional reliability. Different measures can improve the reliability andreduce the risk potential.

The principle of safe existence assumes that all components and their relationship aredesigned such that during the operating time all of the probable or possible incidents canbe overcome without failure. This is ensured through

- the corresponding clarification of influencing loads and environmental conditions likeexpected forces, duration, nature of the environment etc.

- a sufficiently safe design based on proven hypothesis and calculation methods,

- various and careful control of the production and manufacturing process,

- component or system investigation for the examination of durability under partly higherstress conditions (stress level and/or stress cycles) and the respective environmentalinfluences,

- determination of the application field outside the range of variation of possiblecircumstances of failure.

It is characteristic that safety here only lies in the exact knowledge of all influencesregarding quantity and quality respectively the knowledge of the failure-free area. Tofollow this principle, either appropriate experience is required or, very often, substantialeffort of pretests and a continuous monitoring of the material and component condition,hence money and time.

Anyhow, should there be a failure and one was dependent on the safe existence,generally it is the case of a major accident, e. g. break of an aircraft wing, collapse of abridge.

The principle of limited failure allows a malfunction and/or a break during the operatingtime, without allowing serious consequences. In this case

- a function or ability, even if limited, that prevents a dangerous state, needs to bepreserved,

- the limited function of the failing or another component needs to be taken over and beperformed until the system or machine can be taken out of operation safely,

- the error or failure need to become visible,

- the area of failure needs to allow an evaluation of its for the total security decisivestate.

Basically, while restricting a main function a warning is used that can occur in many ways:increasing ride disturbance, leakage, power drop, movement obstruction, in each casewithout causing danger.

There are also other warning systems conceivable to report humans the beginning of afailure. These should also be designed following the principles of safety systems. Theprinciple of limited failure requires the knowledge of the damage process and aconstructive solution that can take over or preserve the limited function in case of failure(Pahl 2005).

If the probability of a damaging event of a subsystem i is known, the probability of non-availability V for the entire system can be calculated. One can distinguish systems withAND and OR gates. An example of an AND-gate could be the parallel production of thesame component in multiple work systems. The probability of non-availability of the entiresystem is the result of the product of the probabilities of non-availability of the individualsubsystems. The lower the number of subsystems is, the higher the probability that theentire system may fail. With an increasing number of subsystems the probability of non-availability of the entire system approaches zero.

Example of an OR-gate is the serial production of a component. The probability of non-availability of the entire system can be determined according to the equation above. Thesmaller the amount of subsystems, the lower the probability of failure of the entiresystem. Mathematically, for the probability of non-availability V a linear relation on thenumber of linked systems results (as seen in the illustration at the bottom left).

According to the TOP-Model, for the safety of a working system the following conditions matter:

T: technical measures= safety-related solutions are constructively provided

O: organizational measures= failure-free execution conditions and safe procedures are planned

P: personal measures= the working human contributes to safety, actively or passively, directly or indirectly, for himself or others.

Risks for the working human should be eliminated or minimized with measures of highest reliability and effectiveness. As long as technical solutions are not possible or sufficient, organizational measures need to be met, e. g. with which is regulated, that during a manufacturing process persons cannot enter the danger zone (Pieper u. Vorath 2005).

1. Avoid/eliminate/reduce source of danger; change potential endangering characteristics of a source (primary measures): T

Measures which ensure that no dangers emerge respectively that existing dangers become eliminated. This especially contains the design respectively selection of the technics (including technology) as well as the use and selection of materials, with the aim that sources of danger do not exist respectively that risks do not emerge while using the technics. Measures have to act/work directly at the source of danger (ArbSchG §4 2. „Risks shall be combated at their source“).

2. Safety-related measures (separation of the source) (secondary measures): T

Measures which ensure that sources of danger do not come into operation. This especially contains the security-related measures (like protective systems) with the special aim to control existing and/or expected risks (for example, through shielding or blocking- thus: spatial separation between source of danger and human).

3. Organizational measures (spatial/temporal separation of factor and human): O

Use of organizational safety measures to control those risks that still remain after the use of special safety-related installations. This especially includes the regulations, determinations and practices like work organization, work process, work tasks, cooperation, information (respectively the installation of hints and warning signs), working time, break-time and shift design, employment restrictions

and prohibitions.

Organizational measures prevent dangers to come into operation. In terms of necessary information, contents in operating instructions, rules, license etc. serve as organizational safety measures as well. Organizational safety measures always refer to concrete working systems and affect the concrete manner of the local risk prevention.

The general organization, which takes place at the level of the company respectively organization, is to be defined from the concrete organizational safety measures. The organization of decisions, instructions and information (for example, Standard Operating Procedures (SOPs); often used in the pharmaceutical industry and aviation) are management processes and elements. Such a superordinate organization therefore is not called an organizational safety measure. In this respect organization and acquisition of personal safety equipment (PSE) and the organization of instructions are no organizational safety measures.

4. Use of personal safety equipment: P

Use of personal safety equipment (PSE) for the further reduction of remaining risks of accident and disease.

5. Behavior-related measures: P

Behavior-related safety measures which refer to the characteristic of knowledge, ability and will of the employees and their personality traits, so that these can be adapted to the still remaining risks respectively do not cause them. Behavior-related measures are necessary supplementary measures even for the measures on rank 2 to 4. Only with measures of the first rank the source of danger can be eliminated and therefore the development of dangers and unacceptable risks excluded. Possible impacts of existing dangers are reduced through behavior-related instructions. These are the notice/adherence of operating instructions, hints or warning signs. For example, increasing the personal qualification through instructions, education and (further) training.

The illustrated dynamic protector is a catch equipment for protection from burstingelements at a rupture of the abrasive wheel. The protector only starts its operation when acomponent fails. This happens without signal costs because the rotation energy of thefragments of the shattered wheel are used for the protective effect.

A safety switch for both hands is a protector (safety component). Through the organization of the control devices at a certain area, a safety switch for both hands is a safety measure for the user against reaching the danger zone during dangerous processes. When working with handheld machines it should be considered that the danger zone is not fixed. A switch for both hands is an installation that demands at least the simultaneous operation with both hands to start and maintain the operation of a machine as long as there is a risk, so that in this way a measure for the protection only of the operating person is achieved (DIN EN 574 2008).

Laser sensors offer new concepts for the safety technology. For example, safety areas can be monitored with semicircular distance sensors. The range of the laser beam which senses the protective field with rotating mirrors is a radius of about 15 meters. For the human protection function a distance of 6 meters is approved. Modern devices of this kind allow a programming of the protective field contour respective the local, that are structural or equipment-related circumstances in relation to the danger zone. To the approval of such devices it is related that they are two-channeled (redundancy) in their process structure and have routines for self-monitoring. Regarding the function: For example, the laser beam is moved over the observed area ten times a second. With the beam angle and the duration of a reflected light impulse, the coordinates of the gathered objects are calculated and compared to the contour of the protective field. With correspondingly high approach of a person there is a shutdown of the endangering installation and an alarm signal is output (Hesse 2011).

One procedure for the avoidance or reduction of risks which are caused by machines isthe application of safety distances against reaching the danger zones with the upper andlower limbs. At the determination of safety distances some aspects need to be consideredlike:

- Accessibility situations that first occur at the machine operation;

- reliable reviews of anthropometric data that consider the usually found populations ofthe concerned countries;

- biomechanical circumstances like compressability and stretchability of the body partsand limits of joint mobility;

- technical and practical aspects;

- additional measures for certain target groups (e. g. persons with special needs), thatmight be necessary due to deviations from the defined body measures.

The DIN EN ISO 13857 defines safety distances against reaching mechanical dangerzones for industrial and public zones. The safety distances are suitable for protectingconstructions. Moreover it contains information about distances that prevent the freeaccess with the lower limbs. The DIN EN ISO 13857 refers to persons from 14 years andover (the 5. percentile of the persons from 14 years corresponds to about 1 400 mm).Only for the upper limbs it provides additional information for children older than 3 years(5. percentile of the persons from 3 years corresponds to about 900 mm), when thereaching through an opening is to be considered.

Employer (ArbSchG § 3-14)• is responsible for occupational safety and occupational protection in the business• must determine necessary occupational protection measures through danger assessment• must instruct employees sufficiently and appropriately• should prepare the required materials for the execution of the measuresEmployees (ArbSchG § 15-17)• are responsible for occupational safety and occupational protection at their workplace• are responsible for their own safety oriented behaviors• must avoid every determined danger• should support their employer in ensuring safety and health protectionWorks council (BetrVG)• is responsible for the supervision and adherence to applicable regulations• has the right to help decide on regulations of protection from work accidents and occupational

illnesses• must support the positions responsible for occupational protection• can demand measures for prevention, reduction or for the balancing of stressesSpecialists for occupational safety / safety officers (ASiG § 5-7, UVV (BGV A6))• support employers in the implementation of measures for protection from work accidents and

occupational illnesses• should convince themselves of the correct use of the prescribed protective equipment and

personal safety equipment• should make the insured, aware of accident and health dangers• operating time according to danger ratingCompany medical officer (ASiG § 2-4, ArbSchG § 11)• should examine employees, medically evaluate them, and analyze results in consideration of the

occupation• should provide consultation for the planning, execution and maintenance of workplaces, work

equipment, work procedures and work materials related to occupational-medical interests• should inform the relevant workplaces of uncovered deficiencies and provide suggestions for

possible solutions

Aside from internal actors there are also external actors: the Federal Institute for OccupationalSafety and Health (BAuA), trade supervisory center or National Office of Industrial Safety and thetrade associations.

Avoidance of time pressure: e.g., strict adherence to tight work schedules leads toreduced human reliability.

Safety oriented workplace design: e.g., limited movement possibilities, project machineparts, sharp edges and corners all create typical danger areas danger assessment.

Selection of relevant work procedures and work equipment: e.g., error-free procedures,operational reliability.

Avoidance of danger and human interaction with organizational rules/ regulations: e.g.,co-ordinate safety-critical operations (such as crane-handling in an assembly hangar)with other operating sequences so that uninvolved people are not working in the dangerzone; separate workplaces with toxic substances from “clean” workplaces.

Hannamann’s Human Cognitive Reliability Modell focuses on quantitative predictionsabout the probability of a successful task processing dependent on the standardizedexecution time tn. tn is the quotient from the time frame t available to the operator and theadjusted median of the execution time T1/2ad gained through simulator trials, task analysesand expert interviews.

As presented in the diagram, the probability of error P(t) moves toward 1 when therelationship of the available time to the corrected execution time moves toward 1 or goesbelow it.

Related to Rasmussen’s 3-level model of human decision-making behavior, otherprobability distributions (with a higher time requirement) occur for more complexknowledge and rule-based behavior than for (simple) skill- based task processing. Aperson must be given more time than is needed for a simple reactive task in order toensure a high level of safety during the execution of one of these higher-level tasks.

The amendment of the workplace ordinance (Arbeitsstättenverordnung) of 25 August 2004 replaces the workplace ordinance of 20 March 1975. Aim of the reform is the modernization of the law for work spaces. Instead of rigid guidelines the demands are expressed more generally to meet the different organizational demands more flexibly. There are no changes of the legal situation due to the new structure. A regulatory text contains frameworks that are substantiated through special guidelines in an appendix and it contains rules of procedure. There is an exclusion for workspaces that determines technical regulations for workspaces which replace the former workplace regulations. The technical regulations are then announced by the Federal Ministry of Labor. These regulations affect rooms, climate, illumination, noise and sanitary installations. In the moment, there are no technical regulations for the named areas but only guidelines. Though, these guidelines will be replaced by newer technical regulations in the foreseeable future. To support the implementation for the regulations at this time there are so called action aids circulating which are published by the Federal Committee for Occupational Safety and Safety Engineering. These action aids illustrate an overview on applicable regulations and give concrete benchmarks that can be considered for the planning of workspaces.

According to § 5 of the Occupational Health & Safety Law, every employer has a duty to carry out a danger assessment in the company. Instead of regulating in detail which measures need to be taken for every workplace, the Occupational Health & Safety Law demands a danger assessment by the employer. Before starting the work- and then periodically- the working conditions in the company need to be controlled for and evaluated on dangers. At this, the persons that are responsible for the safety (professionals for occupational safety, fire safety engineers, occupational physicians) are working together. The employee organization needs to be included to the danger assessment as well. The aim is to ensure and improve the safety and health protection of the employees at work with measures of the occupational safety.

When determining dangers holistic thinking is required. At this, questions on workplace design, physical, biological and chemical influences are to be considered as well as the selection of work equipment. Furthermore, working and manufacturing processes, workflows and the organization of working time are under review. Last but not least, the psychological stress of the employees needs to be examined and evaluated (Brenscheidt 2012).

Factor-specific danger assessment

Mechanical dangers

- unprotected moved machine parts

- sharp, spiky, fragile objects

- moved work and transport equipment

Electrical dangers

- components under a voltage of above 50V

- electrostatic charge

Hazardous materials

- gasses

- vapors

- aerosols

- liquids

- solid materials

Biological dangers

- genetically modified organisms

- danger of infection caused by micro-organisms

Fire and explosion dangers

- explosive, highly flammable materials/dusts/vapours/gasses

- highly flammable materials

- oxidizing materials

- pressure tanks and cylinders

Thermal dangers

- hot media/surfaces

- cold media/surfaces

Dangers caused by special physical influences

- noise

- ultrasound/infrasound

- whole body vibration

- non-ionized radiation

- electromagnetic fields

Dangers caused by conditions of the working environment

- climate, temperature, air

- illumination

- drowning

Physical stress

- heavy dynamic work

- one-sided dynamic work

- static work/handling work

Psychological stress

- insufficiently designed working tasks

- insufficiently designed work organization

- insufficiently designed social conditions

Other dangers

- caused by humans

- caused by animals

- caused by plants

Object-specific Assessment

Systematic recognition and evaluation of design deficiencies in work systems and their elements

e.g., through questioning of safety-technical circumstances with checklists according to BetrSichV, App. 1

Task-specific Assessment

Systematic observation of selected safety-critical or danger-prone work procedures according to temporal or circumstantial classification

e.g., evaluation of mental workload with the work task

Event-specific Assessment

Evaluation of unwanted events and their causes and effects

e.g., fault tree (DIN 25424-1), event process (DIN 25419), failure mode and effect analysis (DIN 25448), PAAG

User-specific Assessment

Evaluation of suitability of work systems for particular user groups such as youths, expecting mothers, and handicapped persons via profile comparison between requirements of the work system and the capabilities profile of the users. (Source: Lehder & Skiba, 2005)

Since personal protective equipment can significantly limit or strain the employee, itshould be the last option in order to avoid dangers (behavior-related measures, 4. Level).

All other intervention of technical and organizational occupational safety have precedenceand must have been (in the scope of industrially justifiable) fully utilized.

Personal protective equipment should only be prescribed in a measure necessary for theguarantee of freedom from danger. The use of personal protective equipment leads tofurther reduction of the still remaining risks of accident and disease.

Behavior-related safety measures which refer to the characteristic of knowledge, ability and will of the employees and their personality traits, so that these can meet the still remaining risks situationally respectively cannot cause them. Behavior-related measures are necessary supplementary measures even for the measures on rank 2 to 4, e. g. increasing the personal qualification through instructions, education and (further) training. Only with measures of the first rank the source of danger can be eliminated and therefore the development of dangers and unacceptable risks excluded.

No knowledge: ~ 20 % of all mistakes leading to an accident are caused by occupational beginners / new employees (little experience, lack of instruction and training)

No ability: ~ 10 % of all mistakes leading to an accident are caused by diversion, excessive demand, suitability lacking, fatigue

No will: ~ 70 % of all mistakes leading to an accident are due to the risk taken despite better knowledge of danger and accident-proof behavior (convinced that the danger is not real)

The risks that are related to human errors and their effects are not always predictable in working systems in which humans undertake partial functions. In this context, human errors need to be assumed as inevitable incidents especially when time pressure, emotional stress (depression, euphoria, boredom) respectively inner or outer distractions come into play. To quantitatively estimate human reliability in terms of the probability calculation the human error probability HEP is considered. The complement to the error probability is referred to as the reliability of human actions R.

The human error probability HEP is an estimator for the probability that a given activity is carried out erroneous at any time (Neudörfer 2011).

Possible effects of existing dangers are reduced through behavior-related instructions such as the observance and compliance with the operating instructions, hints or warning signs.