Pollution Dispersion and Predicting Infection Risks in Mobile Public Toilets Based on Measurement and Simulation Data of Indoor Environment

Abstract

Since the 21st century, in several public health emergencies that have occurred across the world, the humid enclosed environment of the toilet has become one of the places where bacteria, viruses, and microorganisms breed and spread. Mobile public toilets, as a supplement of urban fixed public toilets, are also widely used in densely populated areas. According to statistics, since the outbreak of COVID-19 in 2019, multiple incidents of people being infected by the COVID-19 virus due to aerosol proliferation in public toilets have been confirmed. It is an urgent issue to resolve the internal environmental pollution of mobile public health and reduce the risk of virus transmission in public spaces under the global epidemic prevention. This paper utilized a typical combined mobile public toilet as the research object and measured and evaluated the indoor thermal environment in real time over a short period of time. The diffusion mode and concentration change law of pollutants in mobile public toilets were predicted and analyzed based on CFD. Regression analysis was also used to clarify the relationship between indoor thermal environment variables and aerosol diffusion paths, and a ventilation optimization scheme was proposed to reduce the risk of virus transmission.

Indoor Air Quality Improvement in Public Toilets at Railway Stations in China: A Field and Numerical Study

“…The ventilation system has a significant impact on the distribution of pollutant concentrations in the toilet. The upper supply and down exhaust are the best for pollutant emissions from mobile public toilets [33]. What is more, forced ceiling supply and wall exhaust systems proved to be the optimal ventilation systems for bathrooms [25].…”

“…Zhao et al [32] compared the effects of a primary air fan-coil system and an all-air air conditioning system on indoor pollutant diffusion and found that the ventilation design of an all-air air conditioning system with an exhaust height of 400 mm can remarkably improve the indoor environmental health and ventilation efficiency of public toilets. Li et al [33] concluded based on CFD analysis that the pollution emission from mobile public toilets is best done in the form of upper supply and down exhaust. The temperature increased by 1 • C, and the ammonia concentration increased by 0.036 mg/m 3 .…”

Numerical Simulation of Heat Transfer and Spread of Virus Particles in the Car Interior

“…The CFD approach to the study of the spread of viral particles was used to simulate the transmission of the virus in urban public places [46,47], considering different landscape designs and air speeds, in rooms with different partitions [48][49][50][51][52], risks assessment [53][54][55], and construction drainage pipes [56]. Options for optimizing ventilation and air The factors that provide a comfortable microclimate and the theoretical foundations for modeling the microclimate in cabins based on the balance equations of heat flows are presented in [1][2][3][4][5], "the processes of convective heat exchange with the environment are described" [6][7][8][9][10].…”

“…The CFD approach to the study of the spread of viral particles was used to simulate the transmission of the virus in urban public places [46,47], considering different landscape designs and air speeds, in rooms with different partitions [48][49][50][51][52], risks assessment [53][54][55], and construction drainage pipes [56]. Options for optimizing ventilation and air conditioning systems are considered, including the spread of a part of the virus in buildings [57], buses and trains [58,59], and in two-phase flow systems [60][61][62][63].…”