The Mechanics of Slip-and-Fall Accidents
Most of us assume we know what a slip-and-fall accident is. However, legally, medically, and scientifically, it is an amazingly complex occurrence. The following discussion gives us some simplified insight into how we walk and how a slip-and-fall accident comes about.
Walking takes place when the muscles and tendons in our legs expand and contract, controlling the related joints and bones. With one foot forward we transfer our weight from one foot to the other. Because of this, as we walk, our bodies actually swing back and forth.
Our center of gravity (COG), essentially the center of the body, is the balance point around which walking movement operates. This is what helps us maintain our balance and forward movement. However, as our weight is transferred from foot to foot, there is actually a brief period when we lose our balance and are vulnerable to a fall. If there is an unexpected change in the surface and a foot slips or is mispositioned during this brief period, our COG can be significantly impacted and we can lose our balance. If we cannot quickly right ourselves, we fall.*
Kinds of Falls
Falls can be classified into the following four categories:
- Trip-and-fall. This type of fall occurs when we unknowingly encounter a foreign object in our path, such as a power cord, a step, or child's toy on the floor.
- Stump-and-fall. This happens when we encounter an unseen impediment or obstruction on the walking surface such as an uneven floor area, bump on a rug, or a significantly 'tacky' area on the floor.
- Step-and-fall. This is when the surface we are walking on takes an unexpected height change or there is an actual hole in the surface.
- Slip-and-fall. This occurs when our COG is disrupted because we lose secure foot contact with the floor.
Although all four types of falls can result in injury, slips and falls are by far the most common. When a fall of any kind occurs in a healthy adult, if we land on a fleshy part of the body, we typically escape serious injury. However, if we land on a bony part and the fall is relatively violent in nature, the injury can be serious, even severe.
The Bean Bag Test and Floor Safety
Back in the 1930s, it was actually custodial workers that developed a test to determine how slippery a floor was before and after finish had been applied. They called it the bean bag test. A 10-pound bag of beans, connected to a spring scale, was pulled over the floor. If there were six pounds of pull, the floor was determined to be safe. Less than six pounds was considered slippery and over six pounds, the floor was considered tacky, also hazardous.
Today we measure these floor characteristics in a surprisingly similar way but far more accurately. We use the floor's coefficient-of-traction (COF) to measure how slippery it is, and to determine this, a shoe-like material is dragged or pushed over a floor. A COF of 0.5 or less is considered slippery, and more than 0.5 is deemed safe. COF testing is considered very reliable and is used to test flooring materials as well as floor finishes.
However, COF is not reliable in all situations. For instance, shortly after a new shopping center opened, a woman slipped on the tile floor and was injured. The floor had a COF of more than 0.5; when the floor was tested after floor finish was applied, the COF was still in the safe zone. However, it had recently rained when the accident transpired and tests indicated the actual COF with the wet shoes was 0.3. In other words, a slippery condition was created and a slip-and-fall accident was just waiting to happen.
Cleaning and COF
It is fairly obvious that if someone walks over an otherwise safe floor with wet shoes, an accident can occur. However, a large part of the responsibility for maintaining the safety of the floors, in all weather conditions, rests on the shoulders of today's cleaning professionals.
What we have discovered is that improper cleaning methods can make a floor far more slippery than was previously believed. Some hard-surface floors are cleaned using a mop treated with petroleum-based oil. The oil can build up on both flat surfaces and in grout areas, causing the unexpected change in surface contact described earlier that can result in a slip and fall.
Yet it is not just an oil-treated mop that can cause this to occur, but also mops and buckets used for the general cleaning of floors. As mops and buckets become soiled, they spread chemical solution, contaminants, and bacteria over floors. Over time, this can build-up into a slippery residue, reducing its COF and increasing the potential for a slip-and-fall accident to occur. (See sidebar)
One way to prevent this in very large floor areas such as a shopping center floor is to use an auto scrubber to clean the floor. Fresh solution is applied to the floor, the machine scrubs the chemical into the floor, and the squeegee/vacuum system removes the moisture from the floor all in one pass.
However, auto scrubbers are not always applicable to smaller floor areas. Fortunately, other alternatives to mops and buckets have been recently introduced that can also prevent the slippery bacteria residue from developing.
For instance, one trolley bucket system now available dispenses fresh, measured solution directly to the floor as it is rolled over the surface. The floor can then be mopped using microfiber mop heads or brushed, working the solution into the floor and grout areas. The floor is then squeegeed to remove solution, soils, and moisture.
To eliminate mops entirely, which is ultimately the goal, the system can be automated by attaching components that spray cleaning solution onto the floor. After brushing to loosen and remove soils if necessary, solution and contaminants are then squeegeed or vacuumed up. No mops are used in this process.
The Complexity of Slips and Falls
Walking, as we have discussed, is a complex process, and because of this, poor floor maintenance can result in slip-and-fall accidents and injury. Yet sometimes the reasons we lose our balance are more complicated than floor maintenance. These factors include poor lighting in a facility, vision not having adjusted to indoor lighting, being temporarily distracted, walking too fast, or especially for older people, having failing vision.
There is little cleaning professionals can do about these conditions. However, we play a major role in preventing slip-and-fall accidents. And it starts by cleaning floors properly with tools and equipment that remove soils, bacteria, and other contaminants, thereby preventing residue buildup and helping us all stay sure-footed.
*Source: Clayne Jensen, Applied Kinesiology and Biomechanics (1982), and other sources.
Sidebar: How Soapy Floors can Cause a Slip and Fall… Based on an actual incident
A woman was walking into a fast-food restaurant when her right foot slipped and she fell. She filed a lawsuit against the fast-food restaurant because close examination showed that the pores of the normally safe, high COF floor were packed with soap residue, which contributed to the unsafe condition. It was determined the soap residue buildup was the result of the cleaning method used to maintain the floor, which was conventional mopping.
Source: Barry Miller, a Jacksonville, Florida, attorney and safety consultant
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