Iranian Journal of Ergonomics

One of the everyday items needed by human beings at any time and place is the toilet, which must be designed and built with different human dimensions in mind, considering efficiency, maintaining the health of the body and being safe.
The two main types of toilets are designed for use in the squatting-type toilet and the sitting-type toilet (Iranian-Islamic or traditional toilet) [2-5].
There is a strong theory that sitting on a toilet, which is used especially in Western society, physiologically makes it difficult to completely empty the bowel during defecation in such a way that complete emptying does not occur.
One of the most important design parameters of Cai and You was the slope of the footprint on the squat toilet stone. In their study, a slope of 15 degrees was reported with the least amount of fatigue for users. They also examined and reported footprint dimensions, distance, and angle between legs [2]. Therefore, this study was conducted in relation to the design of squat-type toilet stones with regard to ergonomic considerations to eliminate the problems caused by the use of the mentioned toilet.

 

In this study, stratified random sampling was used to select the samples and n= (z_{(1- α/2)} * s) ²/d ²
was used for the sample size. S and d values were determined from previous studies (using the existing Iranian anthropometric tables and the selected anthropometric parameters of this study). α value = 0.05 and the sample size was 61 subjects in the age range of 19 to 60 years. After signing the informed consent form, the participants were assessed in accordance with ethical standards by static anthropometric measurement, and the participants were in perfect physical health and did not report any musculoskeletal impairments or problems.
Seven anthropometric characteristics were measured using a tape measure with an accuracy of one millimeter in these subjects. A questionnaire containing 4 questions was given to them. Each person was squatting for 2 minutes on different slopes from 0 to 20 degrees. Assessment of Localized Postural Discomfort (LPD) by asking people at 3 points of body, at different slopes, and goniometry in the areas of (A), (B) ,(C) and (D) was also performed (Figure 2).
 

Figure 1. Epidural evaluation in the range of 0 to 20 degrees

 

Figure 2. Goniometry of the angles between the sole of the foot-leg (A), thigh-leg (B), thigh-trunk (C) and trunk-vertical axis (D)

Based on the anthropometric characteristics of the individuals, LPD and goniometry findings in different areas of the body and dimensions of toilet in the sole position, length 32.33 and width 12.74 cm was obtained. The angle between the soles of the feet was 23.33 degrees and the required slope of the soles was 12 degrees.
 

 

Figure 3. Minimum, maximum, mean and standard deviation of anthropometric characteristics (according to Table 3)

The toilet is one of the places that everyone needs, it is used in both sitting and squatting forms in different parts of the world, and each of them has its own advantages and disadvantages.
To eliminate the disadvantages of each, it is necessary to evaluate both types of toilets so that according to the results of evaluations, new models can be designed according to the needs of users. In ergonomic squat toilet stone design, user criteria include health measures, shape, ease of use, supporting factors such as handles and other conditions. In relation to the design of this type of toilet, it is necessary to consider the status of people's clothing, such as the use of high heels, tight and long clothes, and also to consider different groups of people, such as children, pregnant women, the elderly and the disabled.
One of the important factors related to the design of the toilet is the limitation in the space intended for it, so that the toilet is often known as the "smallest room in the house". Also, the toilets made in public places space, especially in various means of transport (for example in aircraft), this restriction exacerbates [1].

The findings of this study suggest that modification of the sole position in squatting-type toilet and its sloping design can be effective in making users comfortable. Given the small number of studies on this type of toilet, further studies in this area, including research on specific populations such as the disabled people, children, pregnant women, the elderly, etc., are necessary.
 

The authors thank all those who helped them writing this study.

 

The authors declared no conflict of interest.