Determination of Domestic Kitchen Characteristics for Elderly Turkish Women: A Comprehensive Ergonomics Approach

Objective: The paper aimed to present a layout of the kitchen for elderly Turkish women to assure their safety and comfort while executing their tasks in their kitchen. Background: It is appropriate to regard the domestic kitchen used by an elderly woman as her workplace, requiring application of the ergonomics principles such as environmental conditions, equipment design and workplace layout on the kitchen floor. The purpose is to enable them to perform activities in the kitchen comfortably, safely and without assistance. Ergonomic design takes into account the abilities and limitations due to aging and helps to create the best person-environment fit. Proper design can help all people in all age groups but is particularly important for elderly individuals. Safety, physical and social health must be taken into consideration to increase the quality of elderly Turkish women’s lives. Method: The general layout of the kitchen was designed considering the work triangle, to minimize the walking distance in regard of the work sequence. The required functional anthropometric data for elderly Turkish women were obtained by ratio scaling method using the raw data from previous work. Results: The design of cabinets, worktops, base units, storage areas and their lay-out with kitchen appliances were realized to ensure comfort and safety for the elderly Turkish women. A U-shaped kitchen is found appropriate allowing the elderly woman and her company working together. For the counter, the height of the worktop is found as 860 mm from the floor and a 20 mm thick and 620 mm wide granite block is chosen. Placement of wall cupboards is achieved by considering the vertical grip reach of elderly Turkish women (5%) and the height of each shelf from the floor is determined. Conclusion: The absence of housing standard definitions addressing accessibility of the elderly is an ongoing problem in Turkey. This work presents potential solutions to improve the living standards of the elderly Turkish women. How to cite this paper: Özalp, B.T. (2020) Determination of Domestic Kitchen Characteristics for Elderly Turkish Women: A Comprehensive Ergonomics Approach. Open Journal of Safety Science and Technology, 10, 53-67. https://doi.org/10.4236/ojsst.2020.102005 Received: May 19, 2020 Accepted: June 25, 2020 Published: June 28, 2020 Copyright © 2020 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access


Introduction
Due to improvements in health care, the proportion of senior citizens in the general population of Turkey will continue to increase. The "Turkish Statistical Institute" considers someone of 65 years and more an "elderly" person [1]. Civil servants are retired at the age of 65 in Turkey. In 2017, the population aged 65 years and over was 6.9 million people, which comprises 8.5% of the total population. That year, the elderly female population was 3.9 million, which constitutes 9.6% of the total female population [2]. By 2023, this population will increase to 4.9 million women, and the rate will increase to 11.3%. If this trend continues, the ratio is estimated to increase to 17.7% by 2040 [3]. Because of the rapid increase in the number of elderly women in Turkey, it is imperative to invest in and redesign the kitchen to reduce injuries among this group.

Characteristics of Elderly Women: Physical Changes
Aging is an inevitable process, and old age is known to be the most sensitive era of life. Aging is defined as "the process of progressive change in the biological, physiological and social structure of individuals" [4].
As women age, their sensory systems are affected, including hearing, taste, smell, touch, muscle function and balance [5]. Some sensory systems are more important in everyday functioning than others. As a person ages, they need brighter lights, louder sounds and stronger smells. Color blindness tends to increase, especially among men [6]. For older adults, lights need to be brighter and illumination should be increased by 20% [7]. Cataracts are the most common age-related disorder of the eye. Changes in a person's hearing start at the age of forties and progress with age [5]. Inevitably, the human body and mind age and lose the capabilities that were still available in the middle years [8].
With age, nervous system activities are slowed. Older women are usually slower in receiving information through sensory receptors, slower in transmitting, processing and interpreting information and somewhat slower in acting upon it than younger women [5].
gether with balance disorders, chronic diseases and loss of coordination can result in an increased risk of accidents [9] [10]; furthermore, falls are not only common in developed countries. Reports from developed countries have shown that up to one-third of community-dwelling older adults fall each year, and fall-related injuries and their social consequences have increased [11] [12]. Although problems related to falls have been well studied in developed countries, few studies have been conducted in developing countries [13] [14].
Halil et al. [15] investigated the occurrence of and factors correlated with falls among the elderly in Turkey. A total of 2322 patients aged ≥65 who presented to the outpatient clinic of the reference hospital were questioned for their fall history. 63.5% of the participants were female, and 28.5% of them had fallen within one year. 19.7% of the participants were living alone, while 52.1% were living with her/his partner; 19.1% lived with her/his relatives, and 9.1% were living in a nursing home. Female fall rate was higher than men (32.7% vs 21.3%). Sütoluk et al. [16] reported home accidents, with a male to female ratio of 123 (42.1%) to 169 (57.9%) (p < 0.05). Falls (44.5%) were the major causes of injuries. Falls were significantly more frequent among those 65 years and older compared to younger adults (p < 0.05). While women tended to experience accidents inside the house, men tended to experience them outside the house (p < 0.01). Among all cases, 1.3% were due to domestic accidents, with a higher percentage in women than men.
Şahin and Erkal [17] evaluated the home accidents and fall behaviors of an elderly Turkish population, which included 175 elderly residents in the Ovacık district of the Kırıkkale province of Turkey, by using a questionnaire. The "Falls Behavioral Scale for the Elderly" was employed as the data collection tool. More than half of the elderly population (59.4%) sustained home accidents in the previous year, and elderly individuals who sustained accidental falls (70.2%) and those who experienced accidents in the kitchen (31.7%) ranked first. The mean score of the elderly fall behaviour was 2.85 points on a four-point scale. The fall behaviour of the elderly indicated significant differences in terms of the type and place of accidents (p < 0.05). When group averages were evaluated, the elderly individuals who sustained cuts or home accidents in the kitchen had higher scores on the scale than the other groups.
Determination of risk factors in the kitchens of elderly women may change legal flat regulations for house constructors, which may significantly reduce the number of injuries and disabilities related to household injuries. In fact, elderly people have greater difficulty adjusting to inappropriately high worktops than people under the age of 65. In kitchen design, the optimal heights and depths of worktops and storage places should also be considered in terms of accessibility and the load on the spinal cord.

Risk Factors Associated with Housing Conditions
The main risk factors for all types of home accidents include not only the characteristics of elderly women but also housing conditions. It may be impossible Open Journal of Safety Science and Technology to overcome individual factors, but accidents may be avoided by improving the housing conditions for elderly women; in other words, adopting living space to the needs of elderly women can reduce the risk of injury [9]. In addition to passage areas, such as stairs and hallways, kitchens and bathrooms are particularly important, as they are the places where most accidents occur. Falling on wet surfaces is a major accident that occurs to elderly people in their houses. However, these accidents can be prevented by using a rubber mat with suction cups on one side. The mat is placed on the bathtub or shower stall floor before bathing to prevent slipping. Falling on stairs occurs infrequently (<5% of all falls in the house) [18]. Exposed electrical wiring (extension cords, lamps or telephone cord) within the walking area may be the cause of accidents for elderly women and men.
Statistics reveal that most accidents occur to women aged 65 or more and usually occur in the kitchen and bathroom. Therefore, the aim of the ergonomist should be the redesign of the kitchen and the bathroom for elderly women living alone to enable them to execute their daily activities comfortably, safely and without assistance.
Elderly women spent most of their day cooking, eating and for social activities with friends in the kitchen. Thus, the kitchen should be adapted to the physical and psychological characteristics of elderly people [19]. Câmara et al. [20] suggested the following: 1) Good lighting and easy access to switches is necessary. For that, switches must be easy to use and located 1.10 to 1.30 metres from the floor.
2) Local lighting units, such as 400 mm long fluorescent tubes, can be placed just underneath the cupboard, hung on the kitchen wall just over the dishwasher, sink, oven and work space.
3) The oven, sink and fridge should be placed to form a working triangle.

4)
A minimum space between workbenches should be available to move and work. 5) For placement of cupboards and appliances, one must pay attention to the layout to avoid disturbing the space to circulate and activities. 6) Kitchen can be designed to hold the laundry machine if necessary, but an additional fan over the drier may be needed to address the resulting condensation.
The basic principle of ergonomics or human factors is design to fit the characteristics of the user population. The common underlying assumption is that users are all healthy adults and that the user population is not heterogeneous but is composed of individuals whose characteristics and capabilities are all similar. A kitchen designed for elderly women must have ergonomic dimensions. Attention should be paid to the design of kitchen furniture that complies with the user's stature and posture. Basic dimensions such as size, shape, height, and horizontal or vertical spacing affect entire residential environments and influence the safety and comfort. Accessibility, clearance and reach must cover both horizontal and vertical distance for individual elderly users. Open Journal of Safety Science and Technology

Lillian and Frank Gilbreth's Kitchen Triangle
Frank Gilbreth and Lillian Gilbreth studied the kitchen plan in the 1920s, and Niebel and Freivalds reported their study in 1999 [21]. Their study placed special emphasis on the best flow of activities in the kitchen. The work sequences show that there are three activities that relate to three main appliances: the refrigerator, the sink and the cooker (range). The relationship of these three fittings is commonly referred to as the work triangle or the kitchen triangle. The optimum length of the kitchen triangle is expected to be between 3.6 and 6.6 m. If the length is less than 3.6 m, the worktop length is too short. If it is more than 6.6 m, walking will be time consuming and may tire an elderly Turkish woman. The total length of the three sides of this triangle measured from the centre of each appliance should not be less than 3.5 m or more than 6.5 m long. As a result, a small, relatively compact kitchen is easier to work in than a large kitchen.
Layouts of a simple kitchen could be in-line, L-shaped or U-shaped [22]. The U-shaped kitchen is often the easiest to use as the appliances surround the cook and are set in worktops unbroken by circulation (Table 1) ( Figure 1). U-shaped kitchen is chosen for the elderly Turkish women's kitchen.

Estimated Anthropometric Measurements of Turkish Adults and Effect of Age
According to the standard anthropometric protocols, weight, height, skin fold thickness and arm circumference were determined, and the body mass index (BM1), fat free mass index and arm fat area were calculated for women living in Turkish nursing homes. However, complete body measurements that are necessary for the kitchen design have not been reported. İşeri and Arslan [23] estimated the anthropometric characteristics of the Turkish people. A survey of 4205 samples of 2263 males and 1942 female civilian subjects was conducted in 2007. It contained data from all seven geographical regions in Turkey and from all age groups. They used the "ratio scaling" technique to estimate the updated body measurements mostly used in the industry [24]. With this method, two coefficients were calculated (E1, E2) for each dimension, using data from the reference population. For this purpose, the researchers used Çiner's [25] study of the anthropology of Turkish females as a reference for Turkish females. In this study, anthropometric data of Turkish women aged ≥65 (n = 79) were selected to estimate the updated relevant measurements using the raw population data from İşeri [26]. The list of the calculated body measurements of elderly Turkish women are given in Table 2.

Goals When Designing the Kitchen for Elderly Turkish Women
 Easy to reach the shelves over the counter,  No bending or stretching movements when working in the kitchen,  Simple maintenance and cleaning of the kitchen floor and utensils,  Floor material is non-slip even when wet, and no-threshold entries into the kitchen are used,  A notched profile at the bottom of the every base floor cabinet,  Toe-knee space for close access to the sink and cabinet and control of doors, windows, cabinets, and appliances is effortless/consistent, secure and consistent with common sense,  No-threshold entries into the kitchen.

Prospective Kitchen Characteristics and Discussion
Elderly women become easily tired when they work for a long time in a large kitchen. As a result, they may show decreased stability and may fall down and Open Journal of Safety Science and Technology  1694.28 mm is less than the distance between the range and the refrigerator which is calculated as 2030 mm in this work.

The Kitchen Counter
There has been much controversy about the ideal height of the kitchen countertop, as it must be appropriate for elderly Turkish women whose height (50%) is

The Turkish-Made Range
Nearly all private homes, including both houses and flats, have a kitchen of some kind. Most apartments include a range, a single appliance that incorporates both a stove and an oven in a compact unit. Many elderly women take advantage of this easy solution by installing a range in the kitchen of their house to save space and to increase user convenience. Turkish-made ranges are usually powered by electricity, natural gas or LPG, and its dimensions are 600 × 600 × 840 mm.

Sink, Fridge and Dishwasher
Turkish-made appliances were chosen for the kitchen. Stainless steel sink is 500 mm wide and 780 mm long. It has only a 1.5 bowl, which is 160 mm deep.
The refrigerator is in 600 × 600 × 1750 mm dimensions and the dishwasher with 600 × 600 × 840 mm size is placed on the right side of the sink under the worktop.

Wall Cupboards
Wall cupboards should not be fixed lower than 400 mm above the countertop; otherwise, they will obscure the back of the counter. In the kitchen, which is With the shelf height as 150 mm (where one can place 12 porcelain dishes in a pile or a stainless steel sauce pan easily), the height of the shelves from the floor is given in Table 3.
The wall cupboard should not be too high for the elderly women's kitchen.
Wall cupboard doors should not be too wide, as 300 mm is the ideal maximum 1) There is one over the dishwasher with two doors; each door is 300 mm wide and 440 mm high.
2) The second one is over the sink and has two doors; each door is 360 mm wide and 440 mm high.
3) The third one is over the worktop, which is over the drawers, and has only two doors that are each 300 mm wide.
4) The two-door cabinets are placed on both sides of the range. Each of these doors is also 300 mm wide and 440 mm high.

5)
There are one-door cabinets on the corner of the worktop, which is on the right side of the range. Each of the two cabinets on the corner is 360 mm wide and 440 mm high.

Floor Material
Turkish ceramic floor tiles with dimensions of 400 × 400 mm were chosen for the elderly Turkish women's kitchen. These are tiles whose surfaces are made with matte glaze for better slip resistance than glossy glazes. Their edges are rounded after the tile sizing. This process prevents damage to the user. At the same time, it prevents edge breaks. The 1st drawer, just under the worktop, is used to store the cutlery set for breakfast.

Base Units
The 2nd drawer, just under the first shelf, is used to store the cutlery set for meals.
The 3rd drawer, under the second shelf, is used to store the cutlery used for the meal service.
The 4th drawer is at the bottom is used to provide storage for pots, pans, oven trays, etc.

Waste Bins
For the segregation of kitchen waste, two separate waste bins are considered. The waste should be separated into wet and dry. Wet wastes are biodegradable organic materials that should be composted, and dry wastes are plastic, glass, paper, etc. that should be recycled.
A Turkish-made tandem two-bin waste system is chosen to maximize the usage volume of the cabinets. This system is placed inside the cupboard under the worktop, which is on the left side of the range. The system consists of telescopic rails that are mounted on the base of the cupboard, thus ensuring ease of usage simply by pulling out and pushing in the bins. During the operation, the bin cover is opened and closed automatically. The blue-coloured waste bin in the rear is used for the dry waste, and its volume is limited by 8 litres. Because of the frequency of food preparation and the resulting amount of food waste, a larger wet waste bin (16 L) is placed on the front and is colored green. Items for lifting and handling are commonly packaged into containers, such as boxes, crates, glass or earthenware jars, and pots. Plastic containers are preferred because they are lighter than glass or earthenware jars and pots. Drury [29] has revived the design of these containers; for loads that are to be lifted from the ground, it is advantageous for the width to be less than 300 mm, allowing the object to pass between rather than in front of the knees [22]. Therefore, plastic jars are used for non-perishables and glass jars for honey, jams and sugars.

Pantry Cabinets for Elderly Turkish Women
Shelves are also placed inside the door of the cabinet. Each shelf has 130 × 510 × 120 mm dimensions. When an elderly woman opens the door of her pantry, the complete set of drawers will come out automatically. Shallow shelving on the inside of the cabinet door is a good storage option for canned goods, bottles and spices.

Conclusions
Kitchen accidents happen frequently in old age. The most common mechanisms of injuries are falls. In this work, in order to prevent falls, analysis and application of ergonomics in the kitchen design for elderly Turkish women are presented to enable them to perform their activities in the kitchen comfortably, safely and without assistance, taking into account their abilities and limitations that come as a result of aging.
In order to determine the ideal kitchen characteristics, current literature on ergonomics aspects of housing and living environment was investigated and functional anthropometric data of elderly Turkish women were calculated. The ideal shape of kitchen has been chosen, taking into account the minimum walk-Open Journal of Safety Science and Technology ing distances, comfort and safety parameters. The design, selection and placement of all the necessary kitchen equipment, materials and fittings were realized by considering the accessibility, reach and safety of the elderly women.
Further research should include the effect of good lighting considering both daylight and electric lighting. Higher illumination without glare for working surfaces and high contrast in printed labels must be provided to prevent visual clutter. Moreover the need of functional anthropometric measurements is essential for the ergonomic interior design. More detailed measurements especially for older adults are of critical importance.

Conflicts of Interest
The author declares no conflicts of interest regarding the publication of this paper.