Estimating Airborne Concentration of SARS-CoV-2 RNA Using Quantitative Filter Forensics
Zoe Hoskin, Jeffrey Siegel, SARAH HAINES,
University of Toronto Abstract Number: 297
Working Group: Indoor Aerosols
AbstractThe COVID-19 pandemic has had indescribable impacts on human health and wellbeing, causing over six million deaths worldwide. Environmental monitoring of viral outbreaks, surveilling the presence of viral RNA through media in the environment, has mainly been limited to wastewater analysis and bulk floor dust analysis. However, wastewater analysis is limited to large-scale community surveillance and does not allow for building or room level analysis which is critical to understanding and preventing disease spread. Additionally, though bulk floor dust sampling in buildings does allow for room-level monitoring, dust samples are likely biased towards larger respiratory particles and respiratory particles attached to dust due to deposition. We designed a targeted sampling approach for indoor airborne dust that is inclusive of particle size using established quantitative filter forensics techniques. Portable air filters were deployed for approximately 14 days in both high-traffic areas at the University of Toronto and other community environments as well as within homes of individuals who tested positive for COVID-19. Dust from filters was collected via vacuum extraction, viral RNA was extracted and presences of SARS-CoV-2 was detected and quantified using real time quantitative reverse transcription-PCR (RT-qPCR). Utilizing the flow rate through the filter, the filter efficiency, mass of dust, duration of deployment and quantity of SARS-CoV-2 RNA we were able to estimate the airborne concentration of SARS-CoV-2. Initial results revealed concentrations of SARS-CoV-2 RNA ranging from 0.01 – 1.6 RNA copies/m3 air within rooms of positive individuals. Further work may elucidate the effectiveness of this technique in building level environmental monitoring for COVID-19 and other airborne diseases.