Emission of Airborne Pathogens from Squat and Seated Toilets and the Environmental Mitigation by UV-C LED

Description

Generation of pathogen-laden aerosols through toilet flushing in which pathogens, seeded intoilets has been evident by previous studies. AirborneEscherichia coli, MS-2, SerratiamarcescensandClostridium difficilehave been identified where toilets were seeded withthese pathogens. Pathogen-laden aerosols could be infectious and transmitted throughairborne and/or contact pathways. This is particularly important for persons withimmunocompromised state and age of extremities. Pathogens other than typical intestinalpathogens can also be detected in excreta and infectious including the deadly SARS-CoV andEbola virus. Potentially, these pathogens can be generated by flushing toilets.Emission strength is the most important parameter in risk assessments. Currently, no emissionstrength of pathogen-laden aerosol generated by flushing neither seated nor squat toilets has beenreported. Microbial diversity of these different toilet installations has not been studied. Conventionalculture-based approach has many limitations for detecting airborne microorganisms as theyield can be as low as 50%. Apart from mechanical ventilation which is mainly used to controltoilet odor, there is not yet a technology-driven solution to mitigate airborne exposure risk.Given that the existing body of knowledge is far from sufficient, our goal of this work is tobridge the knowledge gaps in our understanding of pathogen emission during toilet flushing, riskassessment for public seated and squat restrooms, and associated mitigating measures. Includingsquat toilets will be the most important feature of this work.The primary aim will be to investigate the emission strength for squat and seated toilets.Parameters including pathogen load, pathogen size and sequential flushes will be studied undervarious pressure levels and water flow rates. The secondary is to study diversity of microbialcommunities for public restrooms. The final aim is to study the disinfection effectiveness oflocalized UV-C LED. Both experimental and field approaches will be used. Two custom-builttoilet systems will be installed. Field measurements will be taken in public restrooms withsquat only and seated only toilets. Airborne and surface samples will be collected under variousparameters.The output of this work will be significant for all public health stakeholders. It provides thefirst sets of evidences on emission strengths from squat and seated toilets and diversity ofmicrobial communities of these two toilets. Localized UV-C LED could be a promisingsolution. It will impact personal hygiene, domestic environment and design of public spaces.On a larger scale, it will contribute to social, economic and public health policies.