Researchers Harlan Amandus, Jennifer Bell, Hope Tiesman, and Elyce Biddle, all from the National Institute for Occupational Safety and Health (NIOSH), set out to understand and address the nature of slip, trip fall (STF) injuries (this study focuses on the aircraft manufacturing sector, but its results are applicable to all industries). STF events are a leading cause of injury and death at work, home and leisure, yet many ergonomists do not include STF analysis and prevention as part of their practice. Leading ergonomics research organizations, including Liberty Mutual and NIOSH, however, have set their sights on this significant problem, and this article is one of the recent studies on the topic.
The researchers begin by summarizing the magnitude of the problem:
- Slip, trip and fall (STF) events are the second most prevalent cause of lost work days (LWD) among US private industry workers (24.2%).
In 2008, there were 260,610 private industry work-related STF injuries:
- 72,250 in transportation and utilities;
- 52,030 in education and health services;
- 28,530 in construction; and
- 28,430 in manufacturing.
Purpose and Methods
Partnering with a helicopter manufacturer to gain access to detailed payroll, personnel, Workers Compensation, injury and medical records, the researchers set out to:
- determine the leading causes of STFs in the plant;
- determine the indemnity and medical costs associated with the different causes of STF injuries;
estimate rates of STFs associated with employee factors, such as activity group, age, gender, and length of
- make recommendations for STF prevention in the plant.
The study focused on 4,070 production workers employed between 2004 and 2008. STFs were classified as:
- falls to a lower level;
- falls on the same level; and as
- slips, trips, and loss of balance without a fall.
The researchers looked at the data from many perspectives, and interested readers are encouraged to read the complete article (cited below). The following review covers selected study findings of interest.
Over the four year period, 226 STF events were identified among the 4,070 workers, making them the fourth leading cause of recordable injuries, and the second leading cause of LWDs. The STF injury events broke down as follows:
- falls on the same level, 117 (51.8%);
- falls to a lower level, 46 (20.4%); and
- slips, trips, or loss of balance without a fall, 41 (18.1%)
Of the 226 STFs:
- 72 to a trip;
- 70 to a loss of balance, without a fall;
- 55 were attributed to a slip; and
- 22 to a fall.
The researchers identified the following causes (or contributors) for the 226 STF injury events:
slippery surfaces, 52 (23.0%);
- ice or snow, 30
- oil, 14
- objects on the floor, 43 (19.0%);
- walking on level ground, 32 (14.2%);
- surface hazards, 28 (12.4%);
- climbing into, out of, onto, or off of the aircraft from or to a stand, 17 (7.5%);
- falling while seated or standing on a chair or stool, 11 (4.9%)
- standing on machines or equipment, 8 (3.5%); and
- walking up or down stairs, 8 (3.5%).
The researchers looked for age and length of employment effects and found that the STF rates were higher for workers aged 60 and older, but the difference in rates between that group and younger groups were not statistically significant. There was no significant difference associated with the length of employment.
There was a gender effect, however, with females experiencing a significantly higher STF rate ratio than males (calculated by considering the number of STF events over the number of hours worked).
The researchers were able to establish the following Workers Comp and indemnity costs related to STFs:
- total STF costs over 4 year study: $2,238,850 (16% of all injury costs);
- falls had the highest average cost per injury ($10,108) and cost per claim ($22,532);
- falls on the same level had the highest total cost ($1,405,302), average cost per injury ($12,011), and average cost per claim ($26,515);
the total cost was highest for STFs on slippery surfaces ($856,043), followed by all others ($694,905), objects on the floor ($522,408), and
surface hazards ($165,495);
- among events caused by slippery surfaces, slipping on ice cost $698,012 (82% of the cost of all STFs caused by slippery surfaces), an average cost per injury of $23,267 and cost per claim of $53,693.
Why This is Important to Ergonomists
Slips, trips and falls are well within the purview of ergonomics science, profession and practice. For various political and market reasons, STF accidents have taken a back seat to musculoskeletal disorders (MSDs) in ergonomics practice, but it is time to refocus on the broader benefits of ergonomics, including the reduction/prevention of STF accidents and their costs. NIOSH and Liberty Mutual are leading on the research front, and practitioners should take the lead on the factory/office floor. As this study's authors point out in their discussion, more than half of the STF events in this manufacturing facility "were caused by slippery surfaces, objects left on the floor, and surface hazards … This is not a surprising result and has been found in other industries."
That is, housekeeping and grounds maintenance procedures could significantly reduce the number and cost of STF events. Sometimes improvement opportunities really are this simple, yet remain untapped. An ergonomics approach will also address the non-housekeeping causes of STFs, but the overriding message from this study is that half or more of the STF burden could be solved through housekeeping efforts. As further evidence, the authors cite another study that showed a 58% reduction in STF rates in three hospitals from a prevention program most heavily weighted toward housekeeping and maintenance. Preventing STF accidents is a ripe opportunity for a significant return on investment (ROI).
Also, if you are looking for yet another connection between ergonomics and lean management methods, this is a strong one. 5S, one of the most common tools in the lean enterprise, has a heavy focus on housekeeping practices that reduce clutter and keep work areas clean and organized. Spaghetti diagrams, another shop-floor tool for lean, captures travel path inefficiencies and barriers, and can also be used to reduce STFs.
Early in my career I was involved in several STF research and application projects, which later led to being called upon for STF accident investigations. I've since been curious to see STFs take a back seat to MSDs in the practice of ergonomics, and am glad to see ergonomists re-expanding the value we bring to organizations and society.
At the time of this writing, the complete article was available online at no charge (open access).
Harlan Amandus, Jennifer Bell, Hope Tiesman and Elyce Biddle. The Epidemiology of Slips, Trips, and Falls in a Helicopter Manufacturing Plant, Human Factors: The Journal of the Human Factors and Ergonomics Society, published online, 7 April 2011. DOI: 10.1177/0018720811403140. The open access online version of this article can be found at: http://hfs.sagepub.com/content/early/2011/04/15/0018720811403140
This article originally appeared in The Ergonomics Report™ on 2011-10-26.