Redesigning public squat toilets ergonomically: Understanding gender disparities in foot span and squatting balance

This study assessed sex differences in natural squatting postures in public squatting toilets by collecting data on the span between feet (SBF), the angle between the feet, and the overall stability index (OSI). Sixty participants were recruited, and 24 experimental squatting toilets were simulated by comparing the inner shape, frame, antiskid design, and size of the most comfortable squatting posture for each toilet, plus the subjective comfort evaluation. The results showed a significant sex difference in squatting toilets. The comfortable outward angle between the feet was 40.56° and 28.99° in men and women, respectively. The inner shape only impacted the SBF, while irregular frames resulted in a higher OSI than square frames. In terms of subjective perception, O-shaped internal structures and square frames were the most popular. The SBF of the natural squatting positions of men and women can provide a reference for the design of an optimal squatting toilet.