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Risk Reduction

According to Final Report of the Consumer Product Safety Commission (1970): "Risks of bodily harm to users are not unreasonable when consumers understand that risks exist, can appraise their probability and severity, know how to cope with them, and voluntarily accept them to get benefits that could not be obtained in less risky ways."

This implies that preventable risk is unreasonable when people are not given the opportunity to reduce their exposure to danger. More specifically, that risks of bodily harm to users are unreasonable when users:

Accident Sequence Model

A valuable tool in risk reduction is the accident sequence model, which prompts the following questions:

  1. Can the person detect the hazard?

For example, is there sufficient light and contrast for an object to be seen?

  1. Can he or she identify the hazard?

Identification requires more information than detection. For a state to be identified, it must be attended. Given adequate light, our best vision is achieved for the image of objects that are focused onto the fovea.

The visual field associated with the images of objects focused onto the fovea has been termed the "effective visual field." It is very narrow.

However, due to eye and head movements, we can make rather fine visual discriminations within a cone-shaped space that extends about 15 degrees about the major line of sight. If an object falls outside the central visual field, it may not be attended to at all unless its physical features make it conspicuous. This model of perception suggests that states, in effect, compete with one another for our attention. Conspicuity pertains to how well an object fares in this competition.

  1. Can the person accurately perceive the attributes of the hazard?

Inaccuracy can be the consequence of a lack of information, misleading information, or the erroneous evaluation of information. For example, our ability to perceive the color of objects that are viewed peripherally depends, in part, on their color. We have the widest field of view for blue and yellow and the narrowest for red and green. All other factors being equal, yellow is a good choice for alerting pedestrians to ground-level hazards.

  1. Is the individual alert to the danger?

At any moment, our ability to attend to our surroundings is limited. To compensate, we sample our surroundings for information in short glances. We depend on judgment, prediction, and expectancy to fill the gaps. Expectancy concerns our readiness to respond to situations in predictable ways. When a situation is at odd with our expectancies, surprise, confusion, errors, and accidents are more likely to result. Consequently, if an unexpected hazard cannot be eliminated through design, or exposure to it prevented through adequate guarding, then it is necessary to alert users to the danger.

  1. Does the person appreciate the level of risk?

Information has been informally defined as "any difference that makes a difference." Alerting people to the presence of a hazard may make little difference in their behavior if they erroneously perceive the level of risk to be low. A warning should not only alert people to a danger, but provide information about the extent of the risk. To illustrate, an operator of a large hydraulic crane was killed when he was pressed against a railing by a section of moving machinery. There was a sign posted that read "Caution, Moving Machinery." However, unbeknownst to the operator, the design of the crane had been modified so that the moving section provided less clearance with the railing than on other cranes of what appeared to be of identical design. In my opinion, the warning sign was inadequate as it did not adequately convey the severity of the negative consequences if it went unheeded. A new warning candidate was developed.

  1. Does the person know how to cope with the hazard?

Information has been more formally defined as "the reduction of uncertainty." Statements such as "provide adequate ventilation" are not very informative as they depend on the user's criterion as to what constitutes "adequate." The argument that a person was injured because he or she failed to comply with a warning is unsound when that warning provides little direction for conduct.

  1. Does the individual have the ability to avoid harm?

Knowing what to do should not be equated with actual performance. For example, most drivers probably know the rule of thumb of what to do if their vehicle goes into a skid. However, unless the operator has had actual experience in the situation, the rule of thumb may not be recalled in time to provide guidance. Further, the ability to avoid harm may be compromised by, for example, age-related changes in sensory and motor ability, by fatigue, sensory overload, and by environmental stressors.

  1. Does the person want to avoid the hazard?

If a person is alert to the danger, appreciates the extent of the risk, knows what to do to avoid harm, and has the ability to do so, and yet adopts, for example, an unsafe work practice, it can be argued that that person has voluntarily assumed the consequences of his or her behavior. Of course, by their very nature, warnings cannot guarantee compliance. In my opinion, the primary function of a warning is to provide information about situations that can cause harm. People have a right to obtain such information even if they choose to ignore it as evidenced by their behavior. Warnings do not take the place of reasonable efforts to eliminate the hazard or protect users from being exposed to it through adequate guarding.

G. David Sloan, Inc.
2934 Steamboat Island NW
Olympia, WA 98502
(360) 866-1768 voice
(360) 866-1810 fax
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Olympia, WA