Test your knowledge: Are these safety rules of thumb true?
June 21, 2010 by Fred HosierPosted in: cost of safety, Hearing, Research on safety, Special Report, What do you think?
PDF - 90% of accidents are caused by unsafe human acts. 10% are caused by unsafe conditions. Sesak and Davis say this is false. Their premise: Accidents are multi-factorial and can’t be simply divided into unsafe acts and unsafe mechanical or physical conditions. Take this example: An employee is late for a meeting. While he’s running through a hallway, he spills his coffee on the floor. He doesn’t bother to clean it up. Another worker, also late, rushes by, sees the coffee, and also doesn’t clean it up. A third worker, also rushing, doesn’t see the spilled coffee, slips and breaks her hip. This example has human and physical causes. Sesak and Davis say both unsafe actions and unsafe conditions are present in most accidents scenarios.
- Indirect costs are 3-5 times the direct costs of accidents. This one falls somewhere in between true and false. The two researchers say there is value in pointing out the indirect costs (replacing workers, paying overtime, loss of productivity, training, etc.) when an employee is injured. However, stating that the exact ratio is always 3-5 times isn’t correct. For example: Let’s say a worker receives a cut which can be treated with a simple bandage. The cost of treatment is quite low. However, the indirect costs of lost productivity would likely be much more than just 5 times the cost of the bandage. In more severe cases, it’s possible for the indirect costs to be closer to the direct costs themselves.
- If you must be within arms’ reach to hear normal conversation, you are exposed to noise at or above 90 decibels and need hearing protection. Sesak and Davis says there research shows this one is true. They created noise at 90 decibels and measured their own hearing zones. At 90 db, they had to come within arm’s length of each other not just to hear that the other person was talking but to understand what was being said.
The two researchers conclude that some rules of thumb can be useful when employed in the safety world. But others can be misleading or even counterproductive.
What do you think of their research? Do you have a favorite alleged safety rule of thumb that you’ve found to be false? Let us know about it in the Comments Box below.
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Tags: indirect costs, noise, rules of thumb, truisms, unsafe human acts
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June 21st, 2010 at 7:21 am
[...] link: Test your knowledge: Are these safety rules of thumb true … Posted in industrial safety | Tags: alabama, auburn, auburn-university, jerry, jerry-davis, [...]
June 22nd, 2010 at 5:57 am
While agreeing that all incidents have both unsafe acts and unsafe conditions involved, the root cause of 90% is an unsafe act. Using their example, I can point out a few behaviors that led to the the injury. First, being late was poor planning, second, running to the meeting while carrying coffee was an unsafe act and third, not cleaning up the splilled coffee is negligent.
June 22nd, 2010 at 6:07 am
The fact still remains that the unsafe act of running was the cause of the spill and therefore caused the chain of events that followed. I believe this to be true about unsafe acts causing 90% of the incidents.
June 22nd, 2010 at 9:14 am
On the accident ratio:
Probably is more than 90% the contribution of human error. If a machine is defective and the employee still uses it, the cause is human behavior.
On the indirect costs ratio:
the concept here is AVERAGE. For sure some cases the indirect cost can be more than 5 times and some other cases less than 3.
On the distance for conversation as indicator of noise level:
It depends on the frequency of the noise, the individuals conditions and environmental conditions (windy, raining). So to establish this rule of thumb as correct is ignoring a good number of variables.
June 22nd, 2010 at 10:16 am
In reply to the coffee senario, sometimes the behavior problem is historical. In this case installing the coffee maker in the meeting room eliminates the opportunity to spill coffee on the way to the meeting regardless of how many people are late or running.
June 22nd, 2010 at 10:24 am
It all boils down to the choices people make, given the conditions presented to them. Personally I believe 90% to be a conservative number. Over the years of working accident investigations, I have observed the vast majority of accidents to be caused by a worker’s poor judgement and/or failure to follow the policies and procedures designed to mitigate or minimize the potential for incidents to occur in the first place. We tend to rely on people’s common sense when in today’s work force it is often not so common.
June 22nd, 2010 at 10:43 am
It was always preached to me that ALL accidents are preventable, I have seen nothing yet to convience me otherwise.
June 22nd, 2010 at 11:14 am
I have to take an extreem objection to the example by Sesak and Davis. The broken hip is directly due to an individual who spilt coffee. Therefore the cause is human error! The employee may not fully realize he/she spilt coffee and the next person suffers the consequence. The only physical cause is the floor surface having a smooth surface/low COF. Perhaps if the floor was carpet they would not have slipped.
A careless employee is the direct cause “unsafe human act”, If 100 out of 100 people slipped on the floor with spilt coffee I then could assign a physical cause. Running in the hall could also be considered an “unsafe human act”.
Hum???
June 22nd, 2010 at 11:30 am
Although I do still believe that 90% of accidents are caused by unsafe acts, I have seen in many cases that the unsafe act was caused by a lack of training by the employer, which is then, I believe, an unsafe condition.
Direct and indirect cost, I agree with the professors. It is too variable, depending on the incident.
The rule of thumb of being arms reach to hear and understand communication is a good one. Its a red flag that needs further looking into. When in doubt, protect the hearing.
June 22nd, 2010 at 11:53 am
I totally agree w/ you guys on this and disagree w/ Sesak and Davis. If he’s going to prove his case he’s going to have to come up w/ a better defense then what he has. I also believe that “most” accidents are preventable and are caused by unsafe acts. I don’t know where these people work but “running” is a safety violations.
June 22nd, 2010 at 12:28 pm
Basic Rule of Thumb…don’t suck it after you’re two! Here’s a basic safety rule - just use good sense…which is certainly not ‘common’.
June 22nd, 2010 at 1:30 pm
In the coffee example, the unsafe condition - slippery floor - was caused by an unsafe act - not cleaning up the spill. Clean up the spill and no one gets hurt on a slippery floor. What Sesak and Davis label as unsafe condition I would label as unsafe equipment. That polarizes the causes to be human on one end and machine on the other. And, many machine/equipment failures are caused by unsafe acts such as failing to properly maintain the equipment. My gut feeling is that unsafe human acts cause 99% of accidents. Think about it. What accidents in the workplace are NOT caused by an unsafe human act or a failure to act in a preventative manner?
June 23rd, 2010 at 4:23 pm
Just because someone publishes something, doesn’t make it true. In regards to the coffee and the 2 individuals you quoted as saying not all “incidents” (there’s no such thing as accidents) can’t be taken down to the root cause of an unsafe act or unsafe condition. This is a simple case many inexperianced safety pro’s make of not truely driving down to the root cause due to inexperiance/lack of knowledge/or just plain lazy. I seriously question their expertise if they truely believe that incidents can’t be boiled down to one or the other.
July 2nd, 2010 at 4:10 pm
I tend to favor all 3 cited examples of “rules of thumb”. When I approach a Supervisors or employees it relates, mind numbing engineering numbers do not register - please explain how that would be counterproductive. If I wanted to be exact -I’d bring a book or a power point. This was a useless test and a huge waste of time by those two fellows. Behaviors cause conditions, plain and simple, therefore are the cause of MORE THAN 90% of injuries. And as Safety George so truly states “all accidents are preventable”
August 4th, 2010 at 12:43 pm
Definition of “Rule of Thumb” - A rule of thumb is a principle with broad application that is not intended to be strictly accurate or reliable for every situation. It is an easily learned and easily applied procedure for approximately calculating or recalling some value, or for making some determination. http://en.wikipedia.org/wiki/Rule_of_thumb
We are left to wonder if the researchers that provided the input on this subject were familiar with this definition.