In the early days of the pandemic, researchers proposed that the main route of SARS-CoV-2 transmission was either via large droplets that people exhaled in a projectile motion through coughs and sneezes or via surface contamination. Recent work, however, has uncovered that virus particles can also infect others via long-range spread.

Behind this long-range spread are bioaerosolsTrusted Source, which are droplets or particles smaller than 5 micrometers. What makes them problematic in terms of risk exposure is that they can remain suspended in the air for extended periods and move with air currents.

Larger particles are of lesser concern in that aspect as they tend to sink to the ground and remain there.

The researchers behind a new study, which appears online in the journal Building and Environment, decided to explore this phenomenon further by applying it to classrooms to see whether having students and teachers present in the room would change the SARS-CoV-2 exposure risk.