Ions of one sign, when all the electrons of both signs liberated in a volume of air of

mass one kilogram are stopped completely. Symbol: R.

Gray: the derived SI unit of absorbed ionizing radiation dose or kerma

equivalent to an absorption per unit mass of one joule per kilogram of irradiated

material. Symbol: Gy 1 gray is equivalent to 100 rad.

Dose equivalent: a quantity that expresses the probability that exposure

to ionizing radiation will cause biological effects. It is usually obtained by

multiplying the dose by the quality factor of the radiation, but other factors may be

considered. It is measured in sievert (SI unit) or rem.

Chapter 3: RISK MANAGEMENT

22. SAFETY TERMS

HAZARD in relation to a person is defined as "anything that may result in

injury to a person or harm to the health of a person".

ACCIDENT: unplanned event or happening with the undesirable outcome.

(Fatigue; Illness; Injury)

RISK: The possibility of an unwanted event occurring.

Statistically risk is defined as ratio: R=accidents*1000(people)/people

(workers) for some period; year.

Problem: find risk if known 10 shocks per 10000 workers within a year.

Axiom: all activities are potentially risky.

Safety provides conditions free from risk only with some probability.

23. ACCIDENT THEORIES

SINGLE FACTOR THEORIES stem from the assumption that an accident

is the result of a single cause.

Example: A person in a hurry walks through a poorly lit area and trips over

a piece of wood.

Single Factor Theory Solution: Remove the offending piece of wood to

solve the problem.

The reality is that accidents always have more than one contributing factor.

This theory is generally not accepted by persons who have even the most

basic safety and health training.

The MULTIPLE FACTOR THEORY, says that an accident occurs when a

number of factors act together to cause an accident.

Example: A person in a hurry walks through a poorly lit area and trips over

a piece of wood.

Multiple Factor Theory Solution: to effect a solution the multiple factor

theory would require answers to such questions as:

- Was there a necessity for that person to walk in that area or was there a

safer route.

- If the person was not in a hurry would they have been more aware of their

surroundings and avoided the wood.

- If the area was better lit would the person have avoided the wood.

- Could the wood have been removed.

This and similar ideas are favoured by most experienced safety and health

practitioners.

DOMINO EFFECT THEORY postulates that the events, which lead to an

injury, are like five dominos, standing on end, ready to knock each other over in

They are:

1. social environment - those conditions which make us take or accept risks;

2.undesirable human traits - anger, carelessness, tiredness, lack of

understanding, inattention;

3. unsafe acts or conditions - poor planning, unsafe equipment, hazardous

environment;

4. the accident - the accident occurs when the above events conspire to cause

something to go wrong;

5. the injury - injury occurs when the person sustains damage.

Often accidents occur without injury and they are referred to as near misses.

All too often, these near misses are ignored until, figuratively speaking, the

last domino is knocked over and the injury occurs.

The domino theory has its merits but may be too limited to consistently

reflect reality. A more accurate picture of reality may be gained by combining the

elements of the Multiple Factor Theory and the Domino Effect.

The basic strategy to deal with hazard and to prevent accident is risk

management.

RISK MANAGEMENT considers three steps, which should be taken to

ensure a safe and healthy workplace and prevent accidents. They are based on the

concept that the workplace should be modified to suit people, not vice versa. The

three steps are hazard identification, risk assessment, risk control.

Identifying the Hazard - involves recognizing things which may cause injury

or harm to the health of a person, for instance, flammable material, ignition sources

or unguarded machinery.

Assessing the Risk - involves looking at the possibility of injury or harm

occurring to a person if exposed to a hazard.

Controlling the Risk - by introducing measures to eliminate or reduce the

risk of a person being exposed to a hazard.

24. HAZARD IDENTIFICATION

TAXONOMY represents various hazard classifications (table 2).

Table 2

Genesis

- Natural

- Technological

- Man-made

- Ecological

- Mixed

Consequences

- Fatigue;

Taxonomy

Official standard

Physical

Chemical

Biological

Psychological and Physiological

-

-

-

-

Exposure Time

- Rapid

- Cumulative

Loss (Damage)

-

Social

Sphere

Sport

-

Illness;

Injury

Catastrophe

Fire

Death

GLOSSARY OF TERMS: List of terms identifying hazard.

Abnormal temperature, electricity…

HAZARD QUANTIFICATION:

1. Evaluating parameters of potential hazard, its location, source;

2. Considering conditions of work or life;

3. Assessing parameters against standard provided for considered conditions.

Results of HI is to be written in risk management worksheet.

25. RISK ASSESSMENT

It is like predicting the future.

You can't be really sure; you can only make a 'best estimate' on the basis of

the information available.

When assessing risks one should consider likelihood and consequences of

the accident.

LIKELIHOOD - the chance of an event actually occurring:

Very Likely - Could happen frequently

Likely - Could happen occasionally

Unlikely - Could happen, but only rarely

Highly Unlikely - Could happen but probably never will

CONSEQUENCES can be classified as:

Fatal – death;

Major injuries - normally irreversible injury or damage to health requiring

extended time off work to effect best recovery;

Minor injuries - typically a reversible injury or damage to health needing

several days away from work to recover. Recovery would be full and

permanent;

Negligible injuries - would require first aid and may need the remainder of

the work period or shift off before being able to return to work.

RISK RATING is defined from the table 3.

Technical

Ecological

-

-

-

-

-

-

Domestic

Road

Industrial

Military

Table 3

CONSEQUENCE

Fatality

Major injuries

Very Likely

HIGH

HIGH

Risk rating

LIKELIHOOD

Likely

HIGH

HIGH

Highly

Unlikely

HIGH

MEDIUM

MEDIUM MEDIUM

Unlikely

Minor injuries

Negligible injuries

26. RISK CONTROL

RISK CONTROL: the measures we take to eliminate or reduce the risk to an

acceptable level.

Principles of risk control:

- safety standards: acceptable or optimal standards for environmental

parameters: temperature, air quality, maximum weight lift, office time

duration;

- weak link: component inserted in machine or facility, which first reacts to

hazard so that preventing accident: fuse; protecting grounding;

- safety training: providing training to personality working with hazards;

- classification and labeling: dividing objects into classes or categories related

to their hazards: fire and explosion categories of buildings.

Methods of risk control:

- method A: separation people from hazard: remote controls, using robots;

- method B: reducing level of hazard exposure to comply with safety standard;

- method C: adapting people to hazardous environment: feasibility study,

using PPE.

Hierarchy of control measures:

When selecting appropriate measures to control a risk we should select a

control measure from as high on the hierarchy of control list as practicable.

ELIMINATION: the most satisfactory method of dealing with a hazard is to

eliminate it.

Once the hazard has been eliminated the potential for harm has gone.

Example: The dangers associated with transporting an explosive called

Anfo are known and documented. Anfo is made by simply mixing ammonium

nitrate with fuel oil (diesel). Both constituents are safe in isolation but when mixed

they become unstable. The dangers of long distance transport can be removed by

not mixing the component parts until they are on site. By this simple expedient we

have eliminated the hazard.

SUBSTITUTION: This involves substituting a dangerous process or

substance with one that is not as dangerous.

This may not be as satisfactory as elimination as there may still be a risk

(even if it is reduced).

Example: many chemicals can be substituted for other safer chemicals

which perform in the same manner but do not have the same dangers eg. water

based paints rather than those that contain lead.

SEPARATION: Separate or isolate the hazard from people.

This method has its problems in that the hazard has not been removed. The

guard or separation device is always at risk of being removed or circumvented.

Example: A guard is placed over a piece of moving machinery. If the guard