Levels and Particle Size Distribution of Airborne SARS-CoV-2 at a Healthcare Facility in Kuwait

Stern, Rebecca A.; Al-Hemoud, Ali; Alahmad, Barrak; Koutrakis, Petros

The Coronavirus Disease 2019 (COVID-19) pandemic spread rapidly despite extraordinary screening and social distancing measures. Such rapid spread was due in part to the fact that the disease transmission, particularly via airborne spread, is poorly understood. Characterizing the airborne size distribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential to understanding the risk of airborne transmission. We collected size-fractionated (≤2.5, 2.5-10, and ≥10 μm) samples using a cascade impactor at more than 30 locations inside and outside Jaber Hospital and the nearby Temporary Quarantine Facility in Kuwait from April to July 2020. We hypothesized that airborne SARS-CoV-2 would be present in all size fractions, including fine particles, and in a size distribution that differed by sampling location. We found 6% of the samples (13 out of 210) were positive for SARS-CoV-2 RNA. Concentrations ranged from 3 to 25 copies/m3. The size distribution of particle-associated SARS-CoV-2 was different for each location. Large (≥10 μm) particles with the virus were found in symptomatic patient rooms. Fine (≤2.5 μm) particle-associated SARS-CoV-2 was detected in rooms with intubated patients and outside the hospital entrance gates. Coarse (2.5-10 μm) virus-laden particles were present in all locations with positive samples. This is the most comprehensive study to date on size-fractionated airborne SARS-CoV-2 RNA. Our findings support location-specific precautions that mitigate the spread of particles including fine particulate matter over distances greater than 1 meter, including in locations outside the hospital.