Engineering Strategies for Minimizing Particle Escape During Toilet Flushing
MING-ZHEN CHUANG, Shun-Hao Hsu, Sheng-Hsiu Huang, Chih-Wei Lin, Chih-Chieh Chen, National Taiwan University
Abstract Number: 328
Working Group: Reducing Aerosol Exposure with Control Technologies and Interventions
Abstract
The flush toilet, a modern household essential for sanitation and hygiene, has been scientifically proven to be a potential source of environmental contamination. Simply using the toilet can expose individuals to viruses such as hepatitis A, norovirus, or SARS-CoV-2, as well as to chemotherapeutic agents. Numerous studies have successfully detected tracers on surfaces such as toilet floors, seats, lids, flush handles, faucets, towels, and doorknobs, demonstrating that the act of flushing is the primary cause of such contamination. Previous research has conducted preliminary evaluations of the particle generation mechanisms and quantities of commercial toilets. Therefore, the aim of this study was to analyze factors affecting particle escape by improving the design of existing toilets, and to develop a redesigned toilet shape and flushing mechanism that is water-saving, energy-efficient, and capable of preventing particle escape.
In this study, a commercially available toilet was installed inside an acrylic testing chamber, with clean air supplied to prevent interference from external particles. A CPC (TSI model 3022A, St. Paul, MN, USA) was placed at the exhaust end of the chamber to quantify the total number of particles generated per flush. The operational parameters included suction flow rate, shape and position of the air suction port, and the type of filter material used.
Experimental results showed that, under open-lid conditions, each flush released an average of 129,298 particles. Closing the toilet lid reduced particle escape by approximately 25.3%. Replacing the factory-installed activated carbon material with a HEPA filter improved control efficiency to 62%. Furthermore, additional modifications to the suction location and flow rate maximized particle collection efficiency, achieving up to 90%.
In conclusion, applying engineering control strategies to optimize toilet design and air suction mechanisms can actively capture particles generated during flushing, thereby effectively minimizing particle escape and reducing user exposure risks.