Pathogen loading and environmental conditions found in hospital building drainage system wastewater and airflows

The primary aim of a building drainage system (BDS)is to remove waste from a building in a timely and safemanner. Safety, in the main, focuses attention on ensuringthe integrity of water trap seals through the air ventingsystem and pressure alleviation strategy adopted in thedesign. Previous research has described the sonar-liketechnique developed to ensure that depleted water trapseals can be detected and defects rectified to ensure thatmaximum levels of protection are afforded by the BDS.While the technology has been effectively validated by acombination of laboratory investigation, site testing andnumerical simulation; the rationale for the need to monitorwater trap seals is less obvious to professionals operating inthis field. This research reports on a pilot study to quantifythe pathogen loading of waste water effluent from thecollection drain at the Royal Infirmary Edinburgh (RIE) andattempts to trace pathogens in the airflow found in buildingdrainage systems. In effect the research seeks to identify apossible cross-contamination route from patient to infectedfaeces to collection drain waste water effluent to buildingdrainage air flow. In conjunction with the identification ofpathogen by type and species, the airflow rate and direction(up and down), temperature and humidity were recordedto give a holistic view of the environmental conditions inwhich harmful pathogens can survive. Strong positives fornorovirus were detected from samples in the collection draincorresponding to an outbreak in the building, confirmingthat the BDS is contaminated in such circumstances andposes a significant threat.