Virology laboratory biohazards: infectious MS2 aerosols emitted from common procedures and accidental laboratory scenarios in a controlled chamber study.

Infectious viral aerosols outside primary containment represent a profound yet undercharacterized occupational biohazard in microbiological environments. While the role of viral aerosols in laboratory-acquired infections is widely acknowledged, quantitative data on the concentration and size distribution of viral aerosols generated during common laboratory workflows remain limited. This study addresses these gaps by using a controlled chamber to characterize the generation of aerosols containing either a physical tracer, sodium fluorescein, or a viral pathogen surrogate, bacteriophage MS2. By integrating aerodynamic particle sizing with cascade impaction and filtered collection, we quantified the mass, number, and infectivity of aerosols emitted during both routine laboratory procedures and simulated accidental releases. These results reveal that every evaluated action generated measurable aerosols spanning multiple particle sizes. Importantly, all MS2-based actions produced infectious aerosols within the respirable size fraction, confirming that routine benchtop pipetting actions yield viral aerosols. These data provide an empirical foundation for evidence-based risk assessments. IMPORTANCE: Laboratory-acquired viral infections have occurred following routine laboratory procedures in which no distinct accident is recorded, suggesting unrecognized release and inhalation of infectious virus. This research provides a quantitative analysis of these aerosols using a non-pathogenic viral surrogate, MS2, to model viral pathogens. We demonstrate that common laboratory tasks, such as pipetting or handling culture plates, generate respirable infectious aerosols that can bypass standard precautions when outside primary containment. By defining the size and infectious load of these aerosols, this work enables biosafety professionals to transition from qualitative assumptions to data-driven safety protocols, ultimately protecting the personnel responsible for viral pathogen research.