A TOTAL WORKER SAFETY APPROACH FOR
PREVENTING SLIPS, TRIPS, AND FALLS
Hongwei Hsiao, Ph.D.
National Institute for Occupational Safety and Health (NIOSH)
1095 Willowdale Road, Morgantown, WV 26505, USA

Slips, trips, and falls (STF) represent a serious hazard to workers and occupants inmany industries, homes, and communities. Often, the cause of a STF incident ismultifactorial, encompassing human, environmental, and task risk factors. A STFrelated disability can greatly diminish the occupational capability and quality of life ofindividuals in both the home and the workplace. Countering STF hazards and risks bothon and off the job is a “total worker safety” matter, a challenging yet tangible
undertaking. As the federal organization responsible for conducting research for theprevention of work-related injuries in the United States, NIOSH has been conducting
research on STF controls for some decades. Many NIOSH research outcomes havebeen utilized for STF prevention in workplaces, with potential for prevention in homes
as well. This paper summarizes the concept of total worker safety for STF control,
NIOSH priority research goals and activities, and some emerging issues on STF.

Introduction
The most recent report on fatal occupational injuries showed that there were 681slip-trip-and-fall(STF) related fatalities in 2011 in the United States (U.S. BLS, 2013a), which accounted for 14.5%of the overall occupational fatality cases. In addition, there were 299,090 STF-related nonfatal
occupational injuries resulting in days away from work in 2011, which accounted for about 25.3%
of all occupational injuries in that year (U.S. BLS, 2012). The construction industry continued tohave the highest count of STF-related fatalities (U.S. BLS, 2013), and food servers, healthcare
support workers, highway maintenance workers, housekeeping cleaners, and telecommunications
line installers experienced the highest rates of nonfatal STF injuries (U.S. BLS, 2011). Many
countries are facing the same challenges as the United States with STF injury problems in theworkplace (NIOSH, 2011a). Aside from workplace incidents, STFs are the second-leading cause ofunintentional death in homes and communities, resulting in more than 25,000 fatalities in 2009
(NSC, 2011). Often, inhabitants fall from ladders, stairs, uneven surfaces, or wet areas at home.
Elderly individuals are particularly at risk. In 2011, more than 3.3 million nonfatal fall injuries
among older adults (55 ~ 85+ years old) were recorded in emergency departments (NCIPC, 2013).
Similar concerns are seen worldwide (WHO, 2007).
Given the prevalence of STF problems, an organized global research/intervention effort iswarranted. This paper describes a concept for total worker safety for preventing global STFs, which
improves occupational capability and quality of life at both workplaces and homes. The paper alsopresents NIOSH research goals on STF prevention, selected NIOSH research activities relevant tothe concept of total worker safety for STF control, and some emerging issues on STF.

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A Concept of Total Worker Safety for Slip, Trip, and Fall Prevention
STFs occur as a result of a complex interaction of risk factors which can be organized into three
categories: personal, environmental, and task-related factors (Hsiao and Simeonov, 2001). The
personal factors include individual differences (e.g., age, gender, race, and body size), work
experience, chronic illness, physical strength, substance use, cognitive capacities, constraints ofpersonal protective equipment (PPE), visual acuity, contrast sensitivity, discrepant vision between
the eyes, and expiratory flow rate (Hsiao and Simeonov, 2001; WHO, 2007; Knudtson, Klein, &Klein, 2009). The environmental factors concern the information available from visual and physicalinteractions with environments, including elevation perception, moving visual scenes, depth
perception, visual ambiguity, visual detection of obstacles and their properties, restricted support
surfaces, support surfaces inclination, lighting, building design, and material properties of support
surfaces (e.g., friction, contaminants, evenness, loose fixtures, and firmness). The task-related
factors include load handling, physical exertion and fatigue, footwear, complexity of tasks, social
interactions, and community resources (Hsiao and Simeonov, 2001; WHO, 2007).
National and global research efforts on STF are vary among government agencies, healthcare
institutes, professional societies, and individual safety and health research organizations. Many ofthe entities have focused on certain aspects of research topics and applications, such as occupational
issues, biomarkers, forensics, and elderly falls. As national and global communities are moving tobetter workplace safety and quality of life as a whole, countering fall hazards and risks faced byworkers and community-dwellers on and off the job becomes even more inseparable. Workers use
ladders at work; they also use ladders in their homes for household chores. Community members
access building floors through stairways at home as well as at workplaces and public facilities.
Moreover, a STF injury typically affects a person’s ability in handling tasks at the workplace andthe home; it may diminish a person’s social capacity in the community as well. The settings may
differ, but the scientific basis, risk assessment tools, and control strategies for STF remain the same.
The concept of total worker safety for STF prevention considers integration of current knowledge
and research efforts among all aspects to: (1) publicize the importance of STF prevention, (2)advance the identification of risk factors and innovations for STF control, and (3)transfer/implement realistic and effective STF interventions.

NIOSH Research Goals for Slip, Trip, and Fall Prevention
While NIOSH research on STF prevention has been occupational in nature, many of the NIOSH
research findings, methods, and recommendations for safe practices are equally applicable to nonoccupational settings. We are increasing our communication and collaboration with industries,
stakeholders, and global partners to advance research efforts on STF control, which would facilitate
the implementation of a total worker safety strategy to prevent STFs in the workplace, home, andcommunity. Recently, NIOSH has undertaken a concerted effort to update four of its research goals
to address the national STF burden.
Three NIOSH goals for STF prevention research are industry specific, emphasizing program
activities and directions that are likely to have the greatest impact on preventing fall injuries anddeaths in high risk workplaces. They include goals of reducing fall injuries in the constructionindustry, wholesale and retail trades (WRT), and public safety, services, manufacturing, and otherhigh-risk industries. These efforts emphasize implementing effective, evidence-based STF
prevention and protection designs, technologies, programs, and communications materials for: (1)structure design, worksite implementation, and vulnerable group (e.g., Hispanic workers) protectionin the construction industry; (2) the handling, storage, and retrieval of goods in WRT settings; and(3) ambulance, fire truck, and heavy truck apparatus improvements in the public safety sector to
reduce falls from these vehicles and implementation of comprehensive STF prevention programs in-2-the food services industry.
The fourth goal addresses human characteristics, social-organizational characteristics, andbiotechnology-based fall control measures which offer fundamental knowledge and practicalsolutions for STF prevention in the workplace, home, and community. Research organizations canidentify human biomarkers, social-organizational characteristics, and human-system interface traits
that are common precursors to fall incidents, and use them to design out fall risk or craft
engineering solutions and organizational interventions to reduce STF incidences. Accordingly,
manufacturers can produce improved fall protection devices and systems that effectively reduce theforces on the human body during fall arrest and fall impact. Furthermore, safety professionals andresearchers can develop and use comprehensive digital models of human fall dynamics to evaluate
new fall prevention and protection technologies, products, and methods as well as to conduct fallinjury investigations and verify solutions.
NIOSH has proposed retiring the goal to reduce STF injuries in the health services industry,
given productive research that has been conducted as well as industry adoption of recommended
protective measures (NIOSH, 2013). For example, NIOSH has published a user-friendly STF
prevention toolkit targeted toward staff in the healthcare sector that is being adopted by many
hospitals nationwide (NIOSH, 2011b).

Activities and Accomplishments
Selected research projects associated with the four NIOSH overarching research goals are presented
to illustrate our efforts and accomplishments. These projects target high fall-risk industrial sectors
and leading sources of fall incidents which coincide with national workplace and community fallinjury data.

Ladder Safety Research and Innovations

Ladders are one of the most widely-used means of access to elevated surfaces at home and in theworkplace in multiple industries (e.g., construction, wholesale and retail, and public safety sectors).
On average more than 164,000 emergency room-treated injuries in the U.S. each year are related toladders (U.S. CPSC, 2011). What are the current regulations, practice guidelines, and measures tocontrol falls from ladders? What are risk factors, critical knowledge gaps, and emerging issues andtechnologies to address ladder safety? Partnering with ladder manufacturers, a national laddersafety standards committee, technology research organizations, and other U.S. Government
agencies, NIOSH has published literature on solutions and knowledge gaps on extension laddersafety (Hsiao, Simeonov, & Pizatella et al., 2008), identified factors affecting extension ladderangular positioning (Simeonov, Hsiao, Powers, & Kim et al., 2013), and developed and patented aladder safety software application for mobile devices which features a multimodal indicator and agraphic-oriented guide for ladder selection, inspection, positioning, accessorizing, and safe use(Simeonov, Hsiao, & Powers, 2013). The literature, scientific study outcomes, and the mobile
device safety application provide both a scientific basis and practical tools to reduce the risk of fallinjury for millions of ladder users across many industries, homes, and communities.

Slips, Trips, and Falls Control in Food Services

Food preparation workers and non-restaurant food servers are among the groups with high fall-onthe-same-level incident rates, with rates of 61.2 and 65 per 10,000 full-time workers, respectively(U.S. BLS, 2012). Partnering with one of the largest food service companies in the US, NIOSH isevaluating the effectiveness of slip-resistant shoes as part of multi-factor prevention programs in
reducing STF injuries in the food services industry. This study is a randomized controlled trial withthe participation of approximately 4,000 employees for a four year period (Bell, 2009). The research
will impact worker safety by providing scientific evidence and business case support for a-3-

comprehensive STF prevention program to reduce STF injuries among food service workers. Food
service companies, initially hesitant to expend time and money on prevention programs withunknown effectiveness, could use these findings to help justify implementing prevention strategies.
The information will be equally useful for food handling persons at schools and food courts.

Safe Fire Truck Aerial System

A turntable telescopic ladder is perhaps the best-known form of specialized aerial firefighting
apparatus, and is used to gain access to fires occurring at heights or areas inaccessible toconventional ground-based ladders. Ascending and descending aerial apparatus present a significant
source of fall risk due to apparatus space constraints and challenges in firefighter-apparatusinterface design in accommodating the uses at various ladder heights and angles, from almost
vertical to almost horizontal settings. The environmental constraints of firefighting scenes and theincreased physical and mental loads of bunker gear on firefighters often worsen the fall risk.
NIOSH is conducting a series of research projects on the ergonomic design of aerial ladder systems(Simeonov and Hsiao, 2013). Among the objectives are: (1) determination of optimal rung spacing,(2) identification of range of optimal angles for aerial ladder use, and (3) development of an
automated dynamic rung profile that presents a stable horizontal footing surface independent ofaerial ladder slope angle.

Fall-Arrest Harness System Safety

The Occupational Safety and Health Administration (OSHA) mandated a construction standard in1998 that full-body harnesses replace waist belts for fall arrest in personal fall arrest systems (U.S.
DOL, 2011). This provided improved protection against falls from height for 6.3 million
construction workers. Some knowledge gaps remain on suspension trauma risk and how harness fit
affects dynamic loading to the head and neck during fall arrests as well as information about
optimal harness sizing and design to accommodate diverse worker populations. Partnering withharness manufacturers, national safety standards committees, and research organizations, NIOSH
has published improved sizing systems and suggested specification ranges for harness straps (Hsiao,
Friess, & Bradtmiller et al., 2009; Hsiao, Whitestone, & Taylor et al., 2009) and has identified
factors that affect harness-body fit and interface (Hsiao, Whitestone, & Kau, 2007). In addition,
NIOSH has reported the effects of body characteristics and harness fit on human suspension
tolerance time (Hsiao, Turner, & Whisler et al., 2012) and the merits and risks of fall-arrest systemuse for operators of mechanized access platforms (Pan, Powers, & Hartsell et al., 2012 ).

Scaffolding Safety in Fall Injury Prevention

Dismantling of frame scaffolds was reported as one of the most hazardous tasks for the carpenter
trade in the construction industry due to overexertion and fall hazards (National Constructors
Association, 1985). A significant portion of these hazards are associated with scaffold-end-frame(23 kg) dismantling tasks which require both muscle strength and postural balance skills. Most
workers tend to place their hands at the below-hip locations to generate greater lifting power. They,
however, face a fall risk once they lift up the end frame; the center of mass of the end frame is far
above their hands and thus difficult to manipulate. NIOSH studies demonstrated that hand location
between elbow height and chest height with a hand separation distance of 46 cm would allow
workers to generate sufficient isometric strength to disassemble typical 23 kg scaffolds while
concurrently allowing them to mitigate the likelihood of postural imbalance (Cutlip, Hsiao, &Garcia et al., 2002). As scaffolding technology has advanced, mast climbing work platforms (a newelevating system that can lift construction workers to extreme elevations) are increasingly being
used in major construction projects in the U.S. with some 4,200 operations daily (Pan, 2010).
Increasing numbers of high-visibility incidents (i.e., multiple fatalities) have occurred in recent
years in public settings, which concern OSHA and many construction safety officials. NIOSH isconducting research to identify fall protection strategies and effective intervention programs for-4-

workers who are at risk of injury from work at elevation on mast climbing work platforms, using
both computer modeling and field testing approaches. The end products will include
recommendations and informational literature associated with mast climbing work platform fall
protection systems for use by standards committees, manufacturers, employers, and workers.

Human Characteristics and Biomarkers in Fall Injury Controls

The majority of human falls can be regarded as loss-of-balance incidents. Factors that may lead to
disruption of balance include lack of adequate visual cues, inadequate lighting or visual informationin the work environment, narrow and inclined support surfaces, unexpected changes in surface
properties, load handling, physical exertion, fatigue, task complexity that diverts workers’ attention,individual differences, lack of work experience and training, and the physiological and mental load
imposed by personal protective equipment (Hsiao and Simeonov, 2001). NIOSH has conducted aseries of studies on human characteristics and biomarkers with practical implications to advance fallinjury controls. For instance, a simple vertical structure, e.g., a narrow bar, available in line of sightcan serve as a visual cue to assist workers’ balance (Simeonov, Hsiao, & Hendricks, 2009). The
finding may be useful in modifying elevated work environments and construction procedures toimprove workers’ postural balance during construction or structure repair jobs. In addition, atelevation, workers depend heavily on sensory information from their feet to maintain balance.
Sensory suppression associated with elevated vibration levels at a work site may increase the risk oflosing balance. Mechanical vibration transmitted to walking/working surfaces through supporting
structures needs to be controlled when workers are performing tasks at elevation (Simeonov, Hsiao,& Powers et al., 2011). Moreover, NIOSH studies showed that shoes with characteristics of tight fit,
good motion control of the rear, high flexibility of the front, moderate torsional stiffness, and a very
flexible high-cut upper can minimise the risk of loss of balance, making them a better choice thancasual shoes for work on elevated and narrow surfaces (Simeonov, Hsiao, & Powers et al., 2008).

Emerging Issues - For Total Worker Safety for Slip, Trip, and Fall Control
First, populations of a given age, gender, ethnicity, and occupation permutation may have uniquebody size and shape compositions. Workplaces, community environments, and PPE need to beadequately designed to accommodate diverse populations. Through anthropometric research,
NIOSH has provided both scientific theories and practical manufacturing information to advanceharness design for protecting workers from fall injury in the construction sector. Developing
improved protective gear, better home and community environments, and user-friendly assist
devices for fall prevention that fit diverse population groups is a significant agenda for thecommunity. Second, in this new era of changing technology, there are unique issues in the booming
green energy and digital communication businesses in which safety professionals can make asignificant contribution (e.g., safe erection of wind turbines and communication towers). Third,
workers of specific age, social, and economic characteristics may have unique vulnerabilities forfall injury. It is important to focus on these populations, particularly as they have been largely
underserved in the past. One example is the study of the constraints of aging workforces in copingwith injury risks; injury data systems have shown that 42% of fatal STF victims in 2011 were age
55 and above (U.S. BLS, 2013b).
Finally, innovation and implementation should be an important chapter in total worker safety in
STF control. Current design paradigms provide a framework to build upon, but may limit design
creativity. It took 20 years for airbags to become a standard safety device for reducing vehiclecrash-related injuries. While skeptics will always exist with the introduction of new technologies(e.g., the concept of wearable airbags) to combat falls, with advancements in durability andreduction of cost, wearable airbags to reduce fall-related injuries may become an integral part ofworker fall protection systems in the near future. The notion is equally valuable in protecting-5-

inhabitants during household-chore activities (e.g., window cleaning) and reducing resident fallinjury risk in healthcare or homecare settings during daily activities. Furthermore, smart phone
based safety software/applications (apps) represent an emerging area of total worker safety for STF
control; many STF risk exposure assessment tools and safety guidelines can be developed into
mobile apps for STF prevention in workplaces and homes. The NIOSH ladder safety mobile app
mentioned in the “Ladder Safety Research and Innovations” subsection is a successful example.

Summary
STF research has long been recognized as one of the most important and needed areas ofoccupational and non-occupational injury prevention research. The complex and multifactorial
nature of STFs in workplaces, homes, and communities demands a proactive and systematic
approach to prevention. A total worker safety strategy for STF prevention offers an opportunity tointegrate science-based information to publicize the importance of fall prevention and further STF
risk factor identification and control. It also facilitates practical and effective STF innovations andimplementation in the community. To maximize the benefits of the opportunity, collaborations
should be actively implemented among national and international government entities, medical
institutes, technology firms, STF control assist-device developers, and research centers to develop
global research agendas, promote knowledge exchange, and conduct joint research.

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