THE PSYCHOLOGY OF SMELL: WHY EVEN CLEAN TOILETS CAN BE PERCEIVED AS MALODOROUS

ABSTRACT Unpleasant odors in clean restrooms are a common concern for facility users, yet they are often mistakenly attributed to poor sanitation. This study investigates the psychological and technical factors influencing the perception of malodors in visibly clean toilets, with a specific focus on the role of plumbing P-traps. Employing a descriptive-correlational research design, the study combined quantitative and qualitative approaches to examine the relationship between plumbing conditions, user awareness, and odor perception. A purposive sample of 100 respondents, comprising 70 restroom users and 30 facility staff from schools, office buildings, and public facilities, provided data through structured questionnaires, observation checklists, and semi-structured interviews. Descriptive statistics summarized user perceptions, attitudes, and awareness regarding restroom odors, while Pearson’s correlation coefficient analyzed the relationship between plumbing conditions and odor persistence. Thematic analysis of qualitative data identified recurring patterns, including knowledge gaps, maintenance challenges, and user sensitivity to odors. Findings indicate that malodors in clean restrooms are primarily associated with technical issues such as evaporated or stagnant P-trap water, improper installation, biofilm accumulation, and insufficient ventilation. Psychological factors, including sensory sensitivity, prior experiences, and cognitive biases, further influence users’ perception of cleanliness. The study underscores the importance of integrating technical maintenance, odor-control measures, and educational campaigns to enhance restroom hygiene and user satisfaction. Recommendations include regular inspection and maintenance of plumbing systems, staff training, user awareness programs, and improved ventilation to prevent odor accumulation. By addressing both infrastructure and human perception, this research provides actionable insights for facility managers, policymakers, and educational institutions aiming to maintain hygienic and comfortable restroom environments. Keywords: Restroom hygiene, P-trap, odor perception, plumbing maintenance, psychological factors, facility management