Occupational accidents and human errors in apartment custodians’ work

Abstract

BACKGROUND:

According to a survey of the economically active elderly population in South Korea, most of them are employed in the service sector, with many men working as custodians.

OBJECTIVE:

This study investigates the characteristics of injuries affecting apartment custodians, one of the representative jobs for older male workers, as well as the characteristics of accident causes based on human errors.

METHODS:

The study used information processing as a framework to identify the cause of accidents that affected 831 male apartment custodians. This study investigated the characteristics of injured persons and features of accidents.

RESULTS:

The majority of accidents were caused by human errors, in particular perceptual (45.5%) and action (26.9%) errors. The rate of accidents caused by human errors rose from 85.3% among those aged below 60 to 91.4% among those aged 70 or above. Furthermore, the rate of accidents caused by perceptual errors was higher among those aged 60 or above (45.0%) than those aged below 60 (31.4%).

CONCLUSIONS:

The findings of this study imply that accident prevention measures must be customized to older workers according to the different employment conditions.

Keywords

Older workers human error occupational injury custodian information processing

1 Introduction

In line with rising average life expectancy coupled with falling birth rate, the entire world is experiencing an annual increase in the ratio of elderly population aged 65 or above. As of 2010, there were four countries where the elderly population aged 65 or above accounted for 20% or more of the population, namely Japan, Germany, Italy, and Monaco [1]. In Korea, they represented 13.8% of the population as of 2017, [2] but the aging of the Korean population is expected to speed up. The increase in the elderly population aged 65 or above has led to greater social interest in the older segment of the population across the board and a heightened demand for more welfare policies for senior citizens.

According to a survey of the economically active elderly population in Republic of Korea, most of them are employed in the service sector, with many women working as cleaners and men as custodians [2]. ‘Apartment custodian’ is one of the representative service jobs that hire senior men in the aging society. As such, the job entails a range of problems related to the working environment and employment conditions affecting older workers in the service sector. Therefore, the analysis of work-related hazards and injuries of elderly custodians could provide meaningful insight into injury prevention of older workers in general.

In Republic of Korea, an apartment custodian is a poorly paid job relative to the long hours of work and is thus considered one of the jobs that mostly hire senior men aged 60 or above, including retirees [3]. They usually work as temporary workers subcontracted by a third service company, and their job is typically perceived as emotional labor, having to address the various demands of apartment residents. They also have both day shifts and night shifts because they have to respond the needs of residents during the day and fulfill guard duty at night. They work for 12 hours in two shifts— one day and one night— or for 24 hours on alternate days.

Apartment custodians perform a broad range of physical work and spend most of their time standing, walking, bending, and twisting parts of their body. The tools and equipment that they use are also as diverse as their duties. Brooms, rakes, and shovels are used for cleaning, and some tools are used to solve problems of electricity, plumbing, and water leakage. They occasionally have to carry heavy equipment or garbage [4]. They also work with their arms or legs bent while sorting garbage in dirty places, cleaning, or doing repair work [5]. All of this makes them vulnerable to slips and falls from heights, as well as backaches and sprains caused by lifting heavy weights in uncomfortable postures [6]. Back injury, one of the most common injuries among custodians in the United States, can be caused by lifting an object in a wrong posture or dealing with heavy weights in an inadequate manner [7].

Apartment custodians are exposed to a wide range of risk factors as they perform a great diversity of duties despite being some of the oldest workers. Therefore, it is necessary to analyze the risks and accident characteristics of working as a custodian, one of the representative jobs for senior workers with poorer physical and cognitive abilities than the younger counterparts, especially as the job often involves working in a poor environment. Such analysis will contribute to developing effective injury prevention measures for older workers in this aging society. There is a lack of research into human errors around the injuries and accidents of senior workers, who are physically less capable. As such, exploring accidents from the perspective of employees’ human errors will be critical to the successful design of injury prevention policies that take into account the physical and cognitive characteristics of the elderly workers.

This study analyzes injury characteristics from the perspective of human errors based on the accident data of apartment guards recognized as injured persons of work-related industrial injuries. The findings will provide meaningful insight for proposing preventive measures that take into account the characteristics of older workers.

2 Methods

2.1 Classification of accident cause

In South Korea, employers are required to have industrial accident compensation insurance. From the national compensation injury data, we analyzed the cause of accidents. The accident cause is classified into human errors and non-human errors depending on whether it is related to the worker or not (Table 1). Human errors are then divided into perception, cognition, and action based on Wickens’ information processing model [8]. Perception is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information, and cognition is the mental action or process of decision making through thought, experience, and the perception. Action is a physical movement based on decision making. Perception errors include unconsciousness and carelessness, cognitive errors include inexperience or overconfidence, and action errors include inadequate control or excessive force. Non-human errors are divided into violence, facility failure, and traffic accidents.

Table 1
Classification of cause of accident and associated factors

Classification Classification of Wickens et al. (2011) Variable name of this study Description

Human errors

Perception Unconsciousness 1, drowsiness, or heart attack; 0, otherwise

Inattention 1, fail to notice, or carelessness; 0, otherwise

Cognition Inexperience 1, wrong or inadequate procedures; 0, otherwise

Overconfidence 1, overconfidence activity; 0, otherwise

Action Poor control 1, poor control, or unstable balancing; 0, otherwise

Excessive force 1, too heavy weight; 0, otherwise

Other person Violence 1, if violence by visitor; 0 = otherwise

Facility/Tools Facility failure 1 if facility failure; 0 = otherwise

Environments Night/Rain/Snow 1 if dark, rainy or snowy; 0 = otherwise

Vehicle Vehicle accident 1 if struck by vehicle; 0 = otherwise

Classification	Classification of Wickens et al. (2011)	Variable name of this study	Description
Human errors
	Perception	Unconsciousness	1, drowsiness, or heart attack; 0, otherwise
		Inattention	1, fail to notice, or carelessness; 0, otherwise
	Cognition	Inexperience	1, wrong or inadequate procedures; 0, otherwise
		Overconfidence	1, overconfidence activity; 0, otherwise
	Action	Poor control	1, poor control, or unstable balancing; 0, otherwise
		Excessive force	1, too heavy weight; 0, otherwise
Other person		Violence	1, if violence by visitor; 0 = otherwise
Facility/Tools		Facility failure	1 if facility failure; 0 = otherwise
Environments		Night/Rain/Snow	1 if dark, rainy or snowy; 0 = otherwise
Vehicle		Vehicle accident	1 if struck by vehicle; 0 = otherwise

2.2 Classification of custodians’ work

Apartment custodians have patrol duties to ensure the safety of apartment residents and facilities, as well as the responsibility to maintain and repair major facilities. The work of apartment custodians may vary in details according to the size of the apartment, but this study defines them as those who fulfill the following three responsibilities. First, they work mostly in the custodian’s office where they meet the residents’ requests and manage visitor entry. Second, they clean public areas of the apartment complex and patrol major facilities daily and sort garbage regularly. Third, they carry out seasonal landscaping duties including pruning flowers, shrubs, and trees, and removing snow during wintertime. In this study, apartment custodians’ work was allocated, with preliminary approval of the manager, into the following six categories: post service, patrol, facility management, cleaning, pruning, and waste sorting.

2.3 Data collection and analysis

This study covered 814 accidents of male apartment custodians, who were registered for work-related injuries between 2011 and 2012. These were injuries or illnesses that caused at least four days of lost work and included 12 fatalities (1.5%) and 802 injuries (98.5%).

This study identified the direct cause of accidents based on accident summaries in the Report on Industrial Accidents. Furthermore, the characteristics of injured persons (age, duration of employment) and features of accidents (the type of work at the time of an accident, type of accident, the agency of accident) were analyzed.

This study used a χ² test to determine whether the variables in accident characteristics influence the distribution of injured persons according to the accident cause.

3 Results

3.1 Distribution of injured persons by severity of injury

Table 2 shows the distribution of deaths and injuries according to the cause of the accident. In Table 2, as for human errors, action errors (72.4%) was the most frequent cause, followed by perceptual errors (48.2%) and cognitive errors (23.5%). As for non-human errors, 10.0% of accidents were caused by the facility or tools failure, 4.5% by third-party violence, and 1.6% by vehicle accidents within the apartment complex. Furthermore, 49.5% of accidents occurred in a dark workplace, or on a rainy or snowy day.

Table 2
Distributions of injured persons by severity and cause of accident

Cause Classification Death Injury Total

1/0^* No. % No. % No. %

Human errors

Perception 1 9 75.0% 383 47.8% 392 48.2%

0 3 25.0% 419 52.2% 422 51.8%

Unconsciousness 1 7 58.3% 3 0.4% 10 1.2%

0 5 41.7% 799 99.6% 804 98.8%

Inattention 1 2 16.7% 380 47.4% 382 46.9%

0 10 83.3% 422 52.6% 432 53.1%

Cognition 1 2 16.7% 189 23.6% 191 23.5%

0 10 83.3% 613 76.4% 623 76.5%

Inexperience 1 1 8.3% 151 18.8% 152 18.7%

0 11 91.7% 651 81.2% 662 81.3%

Overconfidence 1 1 8.3% 38 4.7% 39 4.8%

0 11 91.7% 764 95.3% 775 95.2%

Action 1 5 41.7% 584 72.8% 589 72.4%

0 7 58.3% 218 27.2% 225 27.6%

Poor control 1 5 41.7% 465 58.0% 470 57.7%

0 7 58.3% 337 42.0% 344 42.3%

Excessive force 1 0 0.0% 119 14.8% 119 14.6%

0 12 100.0% 683 85.2% 695 85.4%

Other cause

Violence 1 1 8.3% 36 4.5% 37 4.5%

0 11 91.7% 766 95.5% 777 95.5%

Facility failure 1 0 0.0% 81 10.1% 81 10.0%

0 12 100.0% 721 89.9% 733 90.0%

Night/Rain/Snow 1 9 75.0% 394 49.1% 403 49.5%

0 3 25.0% 408 50.9% 411 50.5%

Vehicle accident 1 0 0.0% 13 1.6% 13 1.6%

0 12 100.0% 789 98.4% 801 98.4%

Total 12 100% 802 100% 814 100%

Composition ratio 1.5% 98.5% 100%

Cause	Classification	Death		Injury		Total
Human errors
Perception		1	9	75.0%	383	47.8%	392	48.2%
		0	3	25.0%	419	52.2%	422	51.8%
	Unconsciousness	1	7	58.3%	3	0.4%	10	1.2%
		0	5	41.7%	799	99.6%	804	98.8%
	Inattention	1	2	16.7%	380	47.4%	382	46.9%
		0	10	83.3%	422	52.6%	432	53.1%
Cognition		1	2	16.7%	189	23.6%	191	23.5%
		0	10	83.3%	613	76.4%	623	76.5%
	Inexperience	1	1	8.3%	151	18.8%	152	18.7%
		0	11	91.7%	651	81.2%	662	81.3%
	Overconfidence	1	1	8.3%	38	4.7%	39	4.8%
		0	11	91.7%	764	95.3%	775	95.2%
Action		1	5	41.7%	584	72.8%	589	72.4%
		0	7	58.3%	218	27.2%	225	27.6%
	Poor control	1	5	41.7%	465	58.0%	470	57.7%
		0	7	58.3%	337	42.0%	344	42.3%
	Excessive force	1	0	0.0%	119	14.8%	119	14.6%
		0	12	100.0%	683	85.2%	695	85.4%
Other cause
	Violence	1	1	8.3%	36	4.5%	37	4.5%
		0	11	91.7%	766	95.5%	777	95.5%
	Facility failure	1	0	0.0%	81	10.1%	81	10.0%
		0	12	100.0%	721	89.9%	733	90.0%
	Night/Rain/Snow	1	9	75.0%	394	49.1%	403	49.5%
		0	3	25.0%	408	50.9%	411	50.5%
	Vehicle accident	1	0	0.0%	13	1.6%	13	1.6%
		0	12	100.0%	789	98.4%	801	98.4%
Total			12	100%	802	100%	814	100%
	Composition ratio			1.5%		98.5%		100%

Note: ^*1, if the cause of the accident falls into the category; 0, otherwise.

The distribution of injured persons by the degree of injury showed that unconsciousness (drowsiness or heart attack) represented the largest proportion of deaths at 58.3% followed by poor control (41.7%), while poor control (58.0%) and inattention (47.4%) were the major cause of injuries.

3.2 Distribution of injured persons by age

Table 3 represents the age distribution of injured persons according to the cause of the accident. It shows that persons aged between 60 and 69 years accounted for 62.4% of all injuries and those aged 70 or older represented 25.4%, signifying that 87.8% of all injuries affected those aged 60 or older.

Table 3
Distributions of injured persons by age (unit: years) and cause of accident

Cause Classification Under 60 60–69 70 or more χ ² test

1/0⁺ No. % No. % No. % χ ² p value

Human errors

Perception 1 36 36.4% 253 49.8% 103 49.8% 6.279 0.043^*

0 63 63.6% 255 50.2% 104 50.2%

Unconsciousness 1 3 3.0% 2 0.4% 5 2.4% 7.970 0.019^*

0 96 97.0% 506 99.6% 202 97.6%

Inattention 1 33 33.3% 251 49.4% 98 47.3% 8.617 0.013^*

0 66 66.7% 257 50.6% 109 52.7%

Cognition 1 32 32.3% 109 21.5% 50 24.2% 5.521 0.063

0 67 67.7% 399 78.5% 157 75.8%

Inexperience 1 28 28.3% 88 17.3% 36 17.4% 6.854 0.032^*

0 71 71.7% 420 82.7% 171 82.6%

Overconfidence 1 4 4.0% 21 4.1% 14 6.8% 2.368 0.306

0 95 96.0% 487 95.9% 193 93.2%

Action 1 67 67.7% 365 71.9% 157 75.8% 2.409 0.300

0 32 32.3% 143 28.1% 50 24.2%

Poor control 1 50 50.5% 284 55.9% 136 65.7% 8.200 0.017^*

0 49 49.5% 224 44.1% 71 34.3%

Excessive force 1 17 17.2% 81 15.9% 21 10.1% 4.552 0.103

0 82 82.8% 427 84.1% 186 89.9%

Other cause

Violence 1 6 6.1% 25 4.9% 6 2.9% 1.983 0.371

0 93 93.9% 483 95.1% 201 97.1%

Facility failure 1 12 12.1% 48 9.4% 21 10.1% 0.672 0.715

0 87 87.9% 460 90.6% 186 89.9%

Night/Rain/Snow 1 45 45.5% 254 50.0% 104 50.2% 0.744 0.689

0 54 54.5% 254 50.0% 103 49.8%

Vehicle accident 1 1 1.0% 11 2.2% 1 0.5% 2.896 0.235

0 98 99.0% 497 97.8% 206 99.5%

Total 99 100% 508 100% 207 100%

Composition ratio 12.2% 62.4% 25.4%

Cause	Classification		Under 60	60–69	70 or more		χ ² test
Human errors
Perception		1	36	36.4%	253	49.8%	103	49.8%	6.279	0.043^*
		0	63	63.6%	255	50.2%	104	50.2%
	Unconsciousness	1	3	3.0%	2	0.4%	5	2.4%	7.970	0.019^*
		0	96	97.0%	506	99.6%	202	97.6%
	Inattention	1	33	33.3%	251	49.4%	98	47.3%	8.617	0.013^*
		0	66	66.7%	257	50.6%	109	52.7%
Cognition		1	32	32.3%	109	21.5%	50	24.2%	5.521	0.063
		0	67	67.7%	399	78.5%	157	75.8%
	Inexperience	1	28	28.3%	88	17.3%	36	17.4%	6.854	0.032^*
		0	71	71.7%	420	82.7%	171	82.6%
	Overconfidence	1	4	4.0%	21	4.1%	14	6.8%	2.368	0.306
		0	95	96.0%	487	95.9%	193	93.2%
Action		1	67	67.7%	365	71.9%	157	75.8%	2.409	0.300
		0	32	32.3%	143	28.1%	50	24.2%
	Poor control	1	50	50.5%	284	55.9%	136	65.7%	8.200	0.017^*
		0	49	49.5%	224	44.1%	71	34.3%
	Excessive force	1	17	17.2%	81	15.9%	21	10.1%	4.552	0.103
		0	82	82.8%	427	84.1%	186	89.9%
Other cause
	Violence	1	6	6.1%	25	4.9%	6	2.9%	1.983	0.371
		0	93	93.9%	483	95.1%	201	97.1%
	Facility failure	1	12	12.1%	48	9.4%	21	10.1%	0.672	0.715
		0	87	87.9%	460	90.6%	186	89.9%
	Night/Rain/Snow	1	45	45.5%	254	50.0%	104	50.2%	0.744	0.689
		0	54	54.5%	254	50.0%	103	49.8%
	Vehicle accident	1	1	1.0%	11	2.2%	1	0.5%	2.896	0.235
		0	98	99.0%	497	97.8%	206	99.5%
Total			99	100%	508	100%	207	100%
	Composition ratio			12.2%		62.4%		25.4%

Note: ⁺1, if the cause of the accident falls into the category; 0, otherwise. ^*Significant difference at a significance level of 0.05.

This study signifies the growing weakness in perception and action ability with age. The rate of accidents caused by poor control increased with age, rising significantly from 50.5% among those younger than 60 years and 55.9% among those aged between 60 and 69 years, to 65.7% among those aged 70 or older (χ ² = 8.200, p = 0.017). The rate of accidents caused by perceptual errors (χ ² = 6.279, p = 0.043) or inattention (χ ² = 8.617, p = 0.013) also rose significantly from 36.4% and 33.3% among those younger than 60 years to 49.8% and 47.3% among those aged 60 or older. Meanwhile, the rate of accidents caused by inexperience decreased from 28.3% among those younger than 60, to 17.3% and 17.4% among those aged 60 or older (χ ² = 6.854, p = 0.032). Also, there was a significant difference in the distribution of injured persons’ age according to whether the accident was caused by unconsciousness (χ ² = 7.970, p = 0.019).

3.3 Distribution of injured persons by type of work

Table 4 shows the distribution of injured persons according to the cause of accident and type of work. The largest proportion (25.9%) occurred during patrol duty, followed by waste sorting (18.2%), cleaning (16.7%), landscaping and pruning (15.8%), facility management (14.5%), and custodian’s office duty (8.8%) in respective order.

Table 4
Distributions of injured persons by work process and cause of accident

Cause Classification Office service Patrol Facility management Cleaning Pruning Waste sorting χ ² test p value

1/0⁺ 72 211 118 136 129 148

8.8% 25.9% 14.5% 16.7% 15.8% 18.2%

Human errors

Perception 1 36.1% 78.2% 28.8% 41.9% 27.1% 50.7% χ ² = 123.5

0 63.9% 21.8% 71.2% 58.1% 72.9% 49.3% p < 0.001^*

Unconsciousness 1 1.4% 1.9% 0.8% 0.7% 0.0% 2.0% χ ² = 3.6

0 98.6% 98.1% 99.2% 99.3% 100.0% 98.0% p = 0.610

Inattention 1 34.7% 76.3% 28.0% 41.2% 27.1% 48.6% χ ² = 116.7

0 65.3% 23.7% 72.0% 58.8% 72.9% 51.4% p < 0.001^*

Cognition 1 19.4% 4.7% 23.7% 19.1% 45.0% 37.2% χ ² = 91.9

0 80.6% 95.3% 76.3% 80.9% 55.0% 62.8% p < 0.001^*

Inexperience 1 13.9% 2.4% 18.6% 14.0% 37.2% 32.4% χ ² = 87.6

0 86.1% 97.6% 81.4% 86.0% 62.8% 67.6% p < 0.001^*

Overconfidence 1 5.6% 2.4% 5.1% 5.1% 7.8% 4.7% χ ² = 5.3

0 94.4% 97.6% 94.9% 94.9% 92.2% 95.3% p = 0.375

Action 1 38.9% 86.3% 69.5% 86.0% 68.2% 62.2% χ ² = 82.7

0 61.1% 13.7% 30.5% 14.0% 31.8% 37.8% p < 0.001^*

Poor control 1 29.2% 85.8% 42.4% 73.5% 54.3% 32.4% χ ² = 156.9

0 70.8% 14.2% 57.6% 26.5% 45.7% 67.6% p < 0.001^*

Excessive force 1 9.7% 0.5% 27.1% 12.5% 14.0% 29.7% χ ² = 77.6

0 90.3% 99.5% 72.9% 87.5% 86.0% 70.3% p < 0.001^*

Other cause

Violence 1 33.3% 2.4% 5.9% 0.0% 0.8% 0.0% χ ² = 158.1

0 66.7% 97.6% 94.1% 100.0% 99.2% 100.0% p < 0.001^*

Facility failure 1 15.3% 3.8% 16.1% 4.4% 20.9% 6.8% χ ² = 39.9

0 84.7% 96.2% 83.9% 95.6% 79.1% 93.2% p < 0.001^*

Night/Rain/Snow 1 55.6% 74.9% 50.8% 56.6% 1.6% 44.6% χ ² = 178.3

0 44.4% 25.1% 49.2% 43.4% 98.4% 55.4% p < 0.001^*

Vehicle accident 1 0.0% 0.0% 8.5% 0.7% 0.8% 0.7% χ ² = 42.10

0 100.0% 100.0% 91.5% 99.3% 99.2% 99.3% p < 0.001^*

Cause	Classification	Office service	Patrol	Facility management	Cleaning	Pruning	Waste sorting		χ ² test p value
Human errors
Perception		1	36.1%	78.2%	28.8%	41.9%	27.1%	50.7%	χ ² = 123.5
		0	63.9%	21.8%	71.2%	58.1%	72.9%	49.3%	p < 0.001^*
	Unconsciousness	1	1.4%	1.9%	0.8%	0.7%	0.0%	2.0%	χ ² = 3.6
		0	98.6%	98.1%	99.2%	99.3%	100.0%	98.0%	p = 0.610
	Inattention	1	34.7%	76.3%	28.0%	41.2%	27.1%	48.6%	χ ² = 116.7
		0	65.3%	23.7%	72.0%	58.8%	72.9%	51.4%	p < 0.001^*
Cognition		1	19.4%	4.7%	23.7%	19.1%	45.0%	37.2%	χ ² = 91.9
		0	80.6%	95.3%	76.3%	80.9%	55.0%	62.8%	p < 0.001^*
	Inexperience	1	13.9%	2.4%	18.6%	14.0%	37.2%	32.4%	χ ² = 87.6
		0	86.1%	97.6%	81.4%	86.0%	62.8%	67.6%	p < 0.001^*
	Overconfidence	1	5.6%	2.4%	5.1%	5.1%	7.8%	4.7%	χ ² = 5.3
		0	94.4%	97.6%	94.9%	94.9%	92.2%	95.3%	p = 0.375
Action		1	38.9%	86.3%	69.5%	86.0%	68.2%	62.2%	χ ² = 82.7
		0	61.1%	13.7%	30.5%	14.0%	31.8%	37.8%	p < 0.001^*
	Poor control	1	29.2%	85.8%	42.4%	73.5%	54.3%	32.4%	χ ² = 156.9
		0	70.8%	14.2%	57.6%	26.5%	45.7%	67.6%	p < 0.001^*
	Excessive force	1	9.7%	0.5%	27.1%	12.5%	14.0%	29.7%	χ ² = 77.6
		0	90.3%	99.5%	72.9%	87.5%	86.0%	70.3%	p < 0.001^*
Other cause
	Violence	1	33.3%	2.4%	5.9%	0.0%	0.8%	0.0%	χ ² = 158.1
		0	66.7%	97.6%	94.1%	100.0%	99.2%	100.0%	p < 0.001^*
	Facility failure	1	15.3%	3.8%	16.1%	4.4%	20.9%	6.8%	χ ² = 39.9
		0	84.7%	96.2%	83.9%	95.6%	79.1%	93.2%	p < 0.001^*
	Night/Rain/Snow	1	55.6%	74.9%	50.8%	56.6%	1.6%	44.6%	χ ² = 178.3
		0	44.4%	25.1%	49.2%	43.4%	98.4%	55.4%	p < 0.001^*
	Vehicle accident	1	0.0%	0.0%	8.5%	0.7%	0.8%	0.7%	χ ² = 42.10
		0	100.0%	100.0%	91.5%	99.3%	99.2%	99.3%	p < 0.001^*

Note: ⁺1, if the cause of the accident falls into the category; 0, otherwise. ^*Significant difference at a significance level of 0.05.

Table 4 shows that all causes of accidents except for unconsciousness and overconfidence, were found to vary in the distribution of injured persons according to the type of work. The dark, rainy or snowy environment was the greatest cause of accidents that occurred while working in custodian’s office (55.6%), followed by inattention (34.7%) and violence (33.3%). Most of the accidents that occurred during patrol duty were also caused by poor control (85.8%), followed by inattention (76.3%) and dark, rainy or snowy environments (74.9%). The ability to walk safely and preserve balance is dependent on co-ordination of the visual, proprioceptive and musculoskeletal systems, and those functions deteriorate with age. It may be necessary to suggest a higher friction requirement of surface and footwear for the aged population [9].

The cause of accidents during facility management resulted from a dark, rainy or snowy environment (50.8%), followed by poor control (42.4%). As for cleaning accidents, poor control (73.5%) was the most frequent cause, followed by dark, rainy or snowy environment (56.6%) and inattention (41.2%). Accidents during landscaping or pruning work were caused by poor control (54.3%) and inexperience (37.2%) in respective order. The majority of accidents that occurred while sorting waste was caused by inattention (48.6%), followed by a dark, rainy or snowy environment (44.6%) and poor control (32.4%).

3.4 Distribution of injured persons by type of accident

Table 5 shows the distribution of injured persons according to the cause of accident and type of accident. Slips represented the largest proportion of accidents (50.5%), followed by fall from height (14.0%), excessive force (11.3%), struck by objects (8.6%), and puncture (6.8%) in the respective order.

Table 5
Distributions of injured persons by type and cause of accident

Cause Classification Slips Falls Excessive force Struck by Puncture Other χ ² test p value

1/0⁺ 411 114 92 70 55 72

50.5% 14.0% 11.3% 8.6% 6.8% 8.8%

Human errors

Perception 1 69.8% 19.3% 9.8% 48.6% 58.2% 11.1% χ ² = 214.7

0 30.2% 80.7% 90.2% 51.4% 41.8% 88.9% p < 0.001^*

Unconsciousness 1 1.2% 2.6% 1.1% 0.0% 0.0% 1.4% χ ² = 4.5

0 98.8% 97.4% 98.9% 100.0% 100.0% 98.6% p = 0.607

Inattention 1 68.6% 16.7% 8.7% 48.6% 58.2% 9.7% χ ² = 218.9

0 31.4% 83.3% 91.3% 51.4% 41.8% 90.3% p < 0.001^*

Cognition 1 6.8% 35.1% 28.3% 54.3% 83.6% 18.1% χ ² = 234.6

0 93.2% 64.9% 71.7% 45.7% 16.4% 81.9% p < 0.001^*

Inexperience 1 5.4% 20.2% 15.2% 54.3% 81.8% 13.9% χ ² = 261.5

0 94.6% 79.8% 84.8% 45.7% 18.2% 86.1% p < 0.001^*

Overconfidence 1 1.5% 14.9% 13.0% 0.0% 1.8% 4.2% χ ² = 56.6

0 98.5% 85.1% 87.0% 100.0% 98.2% 95.8% p < 0.001^*

Action 1 91.2% 86.8% 92.4% 27.1% 3.6% 12.5% χ ² = 439.4

0 8.8% 13.2% 7.6% 72.9% 96.4% 87.5% p < 0.001^*

Poor control 1 87.8% 84.2% 8.7% 4.3% 1.8% 1.4% χ ² = 522.2

0 12.2% 15.8% 91.3% 95.7% 98.2% 98.6% p < 0.001^*

Excessive force 1 3.4% 2.6% 83.7% 22.9% 1.8% 11.1% χ ² = 424.6

0 96.6% 97.4% 16.3% 77.1% 98.2% 88.9% p < 0.001^*

Other cause

Violence 1 0.0% 1.8% 0.0% 0.0% 0.0% 48.6% χ ² = 768.7

0 100.0% 98.2% 100.0% 100.0% 100.0% 51.4% p < 0.001^*

Facility failure 1 2.4% 39.5% 3.3% 21.4% 5.5% 6.9% χ ² = 157.3

0 97.6% 60.5% 96.7% 78.6% 94.5% 93.1% p < 0.001^*

Night/Rain/Snow 1 66.4% 27.2% 35.9% 20.0% 23.6% 54.2% χ ² = 130.7

0 33.6% 72.8% 64.1% 80.0% 76.4% 45.8% p < 0.001^*

Vehicle accident 1 0.0% 0.0% 0.0% 0.0% 0.0% 18.1% χ ² = 277.4

0 100.0% 100.0% 100.0% 100.0% 100.0% 81.9% p < 0.001^*

Cause	Classification	Slips	Falls	Excessive force	Struck by	Puncture	Other		χ ² test p value
Human errors
Perception		1	69.8%	19.3%	9.8%	48.6%	58.2%	11.1%	χ ² = 214.7
		0	30.2%	80.7%	90.2%	51.4%	41.8%	88.9%	p < 0.001^*
	Unconsciousness	1	1.2%	2.6%	1.1%	0.0%	0.0%	1.4%	χ ² = 4.5
		0	98.8%	97.4%	98.9%	100.0%	100.0%	98.6%	p = 0.607
	Inattention	1	68.6%	16.7%	8.7%	48.6%	58.2%	9.7%	χ ² = 218.9
		0	31.4%	83.3%	91.3%	51.4%	41.8%	90.3%	p < 0.001^*
Cognition		1	6.8%	35.1%	28.3%	54.3%	83.6%	18.1%	χ ² = 234.6
		0	93.2%	64.9%	71.7%	45.7%	16.4%	81.9%	p < 0.001^*
	Inexperience	1	5.4%	20.2%	15.2%	54.3%	81.8%	13.9%	χ ² = 261.5
		0	94.6%	79.8%	84.8%	45.7%	18.2%	86.1%	p < 0.001^*
	Overconfidence	1	1.5%	14.9%	13.0%	0.0%	1.8%	4.2%	χ ² = 56.6
		0	98.5%	85.1%	87.0%	100.0%	98.2%	95.8%	p < 0.001^*
Action		1	91.2%	86.8%	92.4%	27.1%	3.6%	12.5%	χ ² = 439.4
		0	8.8%	13.2%	7.6%	72.9%	96.4%	87.5%	p < 0.001^*
	Poor control	1	87.8%	84.2%	8.7%	4.3%	1.8%	1.4%	χ ² = 522.2
		0	12.2%	15.8%	91.3%	95.7%	98.2%	98.6%	p < 0.001^*
	Excessive force	1	3.4%	2.6%	83.7%	22.9%	1.8%	11.1%	χ ² = 424.6
		0	96.6%	97.4%	16.3%	77.1%	98.2%	88.9%	p < 0.001^*
Other cause
	Violence	1	0.0%	1.8%	0.0%	0.0%	0.0%	48.6%	χ ² = 768.7
		0	100.0%	98.2%	100.0%	100.0%	100.0%	51.4%	p < 0.001^*
	Facility failure	1	2.4%	39.5%	3.3%	21.4%	5.5%	6.9%	χ ² = 157.3
		0	97.6%	60.5%	96.7%	78.6%	94.5%	93.1%	p < 0.001^*
	Night/Rain/Snow	1	66.4%	27.2%	35.9%	20.0%	23.6%	54.2%	χ ² = 130.7
		0	33.6%	72.8%	64.1%	80.0%	76.4%	45.8%	p < 0.001^*
	Vehicle accident	1	0.0%	0.0%	0.0%	0.0%	0.0%	18.1%	χ ² = 277.4
		0	100.0%	100.0%	100.0%	100.0%	100.0%	81.9%	p < 0.001^*

Note: ⁺1, if the cause of the accident falls into the category; 0, otherwise. ^*Significant difference at a significance level of 0.05.

Table 5 shows that all causes of accidents, except for unconsciousness, were found to be different in the distribution of injured persons according to the type of accident. Whenever humans cannot counterbalance slips, then loss of balance and fall will occur. Common conditions related to slips and falls were snow, ice and uneven or damaged paving, secondly, the use of unsuitable and worn footwear [9]. In the case of slip accidents, 87.8% were caused by poor control, followed by inattention (68.6%) and dark, rainy or snowy environment (66.4%). Poor control was the greatest cause of fall accidents from a height (84.2%). Most of ‘struck by’ accidents were caused by inexperience (54.3%) and inattention (48.6%). Also, puncture accidents were caused by inexperience (81.8%), followed by inattention (58.2%).

3.5 Distribution of injured persons by agency of accident

Table 6 shows the distribution of injured persons according to the cause of accident and agency of accident. The study found that it was the ground that caused the largest proportion of accidents at 31.4%, followed by stairs (18.7%), ladder (11.8%), and materials (11.3%) in respective order.

Table 6
Distributions of injured persons by agency and cause of accident

Cause Classification Ground Stairs Ladder Materials Tools Facilities Other χ ² test p value

1/0⁺ 256 152 96 92 42 38 138

31.4% 18.7% 11.8% 11.3% 5.2% 4.7% 17.0%

Human errors

Perception 1 59.4% 84.9% 17.7% 1.1% 31.0% 57.9% 31.2% χ ² = 187.9

0 40.6% 15.1% 82.3% 98.9% 69.0% 42.1% 68.8% p < 0.001^*

Unconsciousness 1 2.3% 0.7% 0.0% 2.2% 0.0% 0.0% 0.7% χ ² = 6.2

0 97.7% 99.3% 100.0% 97.8% 100.0% 100.0% 99.3% p = 0.403

Inattention 1 57.0% 84.2% 17.7% 15.2% 31.0% 57.9% 30.4% χ ² = 186.6

0 43.0% 15.8% 82.3% 84.8% 69.0% 42.1% 69.6% p < 0.001^*

Cognition 1 7.0% 9.2% 34.4% 30.4% 78.6% 52.6% 32.6% χ ² = 159.9

0 93.0% 90.8% 65.6% 69.6% 21.4% 47.4% 67.4% p < 0.001^*

Inexperience 1 5.5% 3.9% 22.9% 21.7% 76.2% 50.0% 28.3% χ ² = 177.2

0 94.5% 96.1% 77.1% 78.3% 23.8% 50.0% 71.7% p < 0.001^*

Overconfidence 1 1.6% 5.3% 11.5% 8.7% 2.4% 2.6% 4.3% χ ² = 19.3

0 98.4% 94.7% 88.5% 91.3% 97.6% 97.4% 95.7% p = 0.004^*

Action 1 89.5% 93.4% 86.5% 83.7% 11.9% 21.1% 32.6% χ ² = 322.3

0 10.5% 6.6% 13.5% 16.3% 88.1% 78.9% 67.4% p < 0.001^*

Poor control 1 86.3% 92.8% 76.0% 16.3% 2.4% 7.9% 11.6% χ ² = 451.9

0 13.7% 7.2% 24.0% 83.7% 97.6% 92.1% 88.4% p < 0.001^*

Excessive force 1 3.1% 0.7% 10.4% 67.4% 9.5% 13.2% 21.0% χ ² = 262.9

0 96.9% 99.3% 89.6% 32.6% 90.5% 86.8% 79.0% p < 0.001^*

Other cause

Violence 1 0.0% 0.0% 1.0% 0.0% 0.0% 0.0% 26.1% χ ² = 177.9

0 100.0% 100.0% 99.0% 100.0% 100.0% 100.0% 73.9% p < 0.001^*

Facility failure 1 2.7% 0.7% 40.6% 17.4% 7.1% 15.8% 6.5% χ ² = 139.6

0 97.3% 99.3% 59.4% 82.6% 92.9% 84.2% 93.5% p < 0.001^*

Night/Rain/Snow 1 70.7% 58.6% 18.8% 37.0% 14.3% 31.6% 45.7% χ ² = 119.6

0 29.3% 41.4% 81.3% 63.0% 85.7% 68.4% 54.3% p < 0.001^*

Vehicle accident 1 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 9.4% χ ² = 64.7

0 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 90.6% p < 0.001^*

Cause	Classification	Ground	Stairs	Ladder	Materials	Tools	Facilities	Other		χ ² test p value
Human errors
Perception		1	59.4%	84.9%	17.7%	1.1%	31.0%	57.9%	31.2%	χ ² = 187.9
		0	40.6%	15.1%	82.3%	98.9%	69.0%	42.1%	68.8%	p < 0.001^*
	Unconsciousness	1	2.3%	0.7%	0.0%	2.2%	0.0%	0.0%	0.7%	χ ² = 6.2
		0	97.7%	99.3%	100.0%	97.8%	100.0%	100.0%	99.3%	p = 0.403
	Inattention	1	57.0%	84.2%	17.7%	15.2%	31.0%	57.9%	30.4%	χ ² = 186.6
		0	43.0%	15.8%	82.3%	84.8%	69.0%	42.1%	69.6%	p < 0.001^*
Cognition		1	7.0%	9.2%	34.4%	30.4%	78.6%	52.6%	32.6%	χ ² = 159.9
		0	93.0%	90.8%	65.6%	69.6%	21.4%	47.4%	67.4%	p < 0.001^*
	Inexperience	1	5.5%	3.9%	22.9%	21.7%	76.2%	50.0%	28.3%	χ ² = 177.2
		0	94.5%	96.1%	77.1%	78.3%	23.8%	50.0%	71.7%	p < 0.001^*
	Overconfidence	1	1.6%	5.3%	11.5%	8.7%	2.4%	2.6%	4.3%	χ ² = 19.3
		0	98.4%	94.7%	88.5%	91.3%	97.6%	97.4%	95.7%	p = 0.004^*
Action		1	89.5%	93.4%	86.5%	83.7%	11.9%	21.1%	32.6%	χ ² = 322.3
		0	10.5%	6.6%	13.5%	16.3%	88.1%	78.9%	67.4%	p < 0.001^*
	Poor control	1	86.3%	92.8%	76.0%	16.3%	2.4%	7.9%	11.6%	χ ² = 451.9
		0	13.7%	7.2%	24.0%	83.7%	97.6%	92.1%	88.4%	p < 0.001^*
	Excessive force	1	3.1%	0.7%	10.4%	67.4%	9.5%	13.2%	21.0%	χ ² = 262.9
		0	96.9%	99.3%	89.6%	32.6%	90.5%	86.8%	79.0%	p < 0.001^*
Other cause
	Violence	1	0.0%	0.0%	1.0%	0.0%	0.0%	0.0%	26.1%	χ ² = 177.9
		0	100.0%	100.0%	99.0%	100.0%	100.0%	100.0%	73.9%	p < 0.001^*
	Facility failure	1	2.7%	0.7%	40.6%	17.4%	7.1%	15.8%	6.5%	χ ² = 139.6
		0	97.3%	99.3%	59.4%	82.6%	92.9%	84.2%	93.5%	p < 0.001^*
	Night/Rain/Snow	1	70.7%	58.6%	18.8%	37.0%	14.3%	31.6%	45.7%	χ ² = 119.6
		0	29.3%	41.4%	81.3%	63.0%	85.7%	68.4%	54.3%	p < 0.001^*
	Vehicle accident	1	0.0%	0.0%	0.0%	0.0%	0.0%	0.0%	9.4%	χ ² = 64.7
		0	100.0%	100.0%	100.0%	100.0%	100.0%	100.0%	90.6%	p < 0.001^*

Note: ⁺1, if the cause of the accident falls into the category; 0, otherwise. ^*Significant difference at a significance level of 0.05.

Table 6 shows that all causes of accidents except for unconsciousness were found to vary in the distribution of injured persons according to the agency of accident. In accidents occurred on the ground, poor control was the greatest cause of accidents (86.3%), followed by dark, rainy or snowy environments (70.7%) and inattention (57.0%). Most of the accidents that occurred on stairs were also caused by poor control (92.8%), followed by inattention (84.2%) and dark, rainy or snowy environments (58.6%). As for ladder accidents, poor control (76.0%) was the most frequent cause, followed by facility failure (40.6%). Accidents during handling materials were caused by excessive force (67.4%) and dark, rainy or snowy environment (37.0%). The majority of accidents that occurred while using tools were caused by inexperience (76.2%), followed by inattention (48.6%). Also, the cause of accidents during handling facilities was inattention (57.9%), inexperience (50.0%), and dark, rainy or snowy environment (31.6%) in the respective order.

4 Discussion and conclusion

With the growing ranks of the elderly population, there is a rising interest in designing job, workplace, and environments tailored to the characteristics of older workers [10 –14]. Designs for the elderly can have different points of focus depending on their health conditions [15]. For those who are in good physical and mental health, the important issue is to provide sufficient opportunities for re-employment, continuing education, appropriate form and hours of work, and work environment, among others [11]. This study analyzed the characteristics of injuries affecting apartment custodians, one of the representative jobs for older workers in Republic of Korea, as well as the characteristics of accident causes based on human errors.

Elderly workers are more susceptible to slips and falls from heights because aging undermines sensory function and perceptive ability as well as the sense of balance and muscular strength [16]. The rate of accidents caused by poor control increased with age, rising from 50.5% among those younger than 60 and 55.9% among those aged between 60 and 69, to 65.7% among those aged 70 or older. Among the injured persons who are younger than 60, 36.4% were involved in accidents caused by perceptual error, and the proportion rose to 49.8% among those who are 60 or older. Poor control also caused most of the accidents that occurred during patrol duty, cleaning, and pruning work. This tendency is also reflected in the distribution of accident types, of which slip (50.5%) and fall from height (14.0%) account for the majority. Also, 87.8% of all slip accidents were caused by poor control, followed by inattention (68.6%) and dark, rainy or snowy environments (66.4%). The findings of this study suggest that there is a need to design workplaces that accommodate the characteristics of older workers so they can work in ease and safety despite their poorer perceptual and action abilities. Therefore, when patrolling or cleaning at night, it is necessary to have auxiliary lighting fixtures, and safety shoes to reduce slip and trip accident.

Custodians, most of whom are aged 60 or older, are vulnerable to physical and mental fatigue as well as other syndromes caused by the nature of work that often involves day and night shifts. Injured persons aged 60 or above accounted for 88.7% of the injured. It makes sense to maintain health and prevent injuries in older workers who are still physically and mentally fit from the social perspective as well since they are a primary source of the workforce in this era of aging population [17 –19]. However, senior workers who are aged 60 or over are susceptible to chronic fatigue and cardiovascular brain conditions under the current system of working for 24 hours on alternate days [20]. This issue could be addressed by improving the current shift system by introducing a subsidy aimed at job creation that is offered to any employees that decrease their shift load by adjusting the number of workers in shift rotation groups from two to three, for instance. Also, there could be a measure to directly support custodians on site by sending counselors or safety trainers to their workplace since custodians work within the limited boundary of the apartment complex and rarely have the time for external programs due to their shift schedule.

5 Limitation and suggestion

The target of this study was limited to accidents that caused four days or more of lost work, which could be a limitation in utilizing the findings. Nevertheless, the results of this study is meaningful in that it explores characteristics of injuries and human errors that affect custodians, a useful insight for developing effective injury prevention policies. It will also contribute to creating workplaces where elderly workers can work in safety in this aging society.

This study is expected to contribute to the healthy work life of the elderly population through its analysis of injuries and proposal of possible prevention measures for custodians, one of the representative jobs for older population. The study also calls for the establishment of ‘universal safety’ as a philosophy for designing environments and products that are convenient and easy for all users in the aging society. This study suggests that ‘universal safety’ should be a systematic activity carried out not just from the perspective of individual workers but also from organizational and environmental standpoints. It should 1) apply to all workers regardless of their employment contract status such as regular workers or subcontractors, 2) cover not only healthy workers but also those with poorer physical or cognitive functions such as elderly workers, and 3) secure a certain level of health and safety required not just by users and customers but also by the workers who produce products or provide services. There should be continuous efforts to expand the current notion of ‘universal design,’ which regards ease of life for the elderly, into the notion of ‘universal safety’ that allows elderly workers to do their job in ease and safety.

Conflict of interest

None to report.

Footnotes

Acknowledgments

This research was financially supported by Hansung University.

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