Monitoring for airborne respiratory viruses in a general pediatric ward in Singapore

Yadana, Su; Coleman, Kristen Kelli; Nguyen, Tham Thi; Hansen-Estruch, Christophe; Kalimuddin, Shirin; Thoon, Koh Cheng; Low, Jenny Guek Hong; Gray, Gregory Charles

Aerosol samples were collected in a general pediatric ward at KK Women's and Children's Hospital, Singapore, using three National Institute for Occupational Safety and Health (NIOSH) two-stage cyclone samplers and one SKC filter cassette preloaded with a 37mm polytetrafluoroethylene (PTFE) filter (0.3μm pore size) designed to sample for severe acute respiratory syndromeassociated coronavirus (SARS-CoV). Aerosol samples were collected once per week for seven weeks in May and June 2017. The NIOSH samplers were stationed on tripods and placed along the corridor outside the open patient bedding area, and one SKC filter cassette was attached to a mobile computer on wheels (COW) used by doctors and nurses during ward rounds. Each sampler was connected to an AirChek® TOUCH Sample Pump (SKC, Eighty-Four, USA) with Tygon tubing (61 cm length, 0.635 cm diameter) for air collection at a rate of 3.5 L/min. A total of 840 L of air was collected during each four-hour sampling period. Each NIOSH sampler separates collected particles into three aerodynamic diameters: >4μm, 1-4μm, and <1μm. 3 Filter cassettes and sample tubes from the NIOSH samplers were stored at -80˚C before processing. Prior to nucleic acid extraction, sample material collected in the 1-4 μm and <1μm size fractions were combined (described below).