Accident theories

SAFETY TERMS

UNITS OF RADIATION

Becquerel: the derived SI unit of radioactivity equal to one disintegration per second. Symbol: Bq [named after A. H. BECQUEREL]

Curie: a unit of radioactivity equal to 3.7 X 10¹⁰ disintegrations per second. Symbol: Ci [ named after Pierre CURIE ]

Quantity of radiation exposure, which has a definite adverse effect, as destroying or ionizing cells, is called radiation dose.

There’re two principally different doses: exposure dose and absorbed dose.

Exposure dose unit is Roentgen: a unit of dose of electromagnetic radiation equal to the dose that will produce in air a charge of 0.258 X 10-3 coulomb on all 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

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.

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 turn.

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.

Дата добавления: 2014-01-04