Natural ventilation performance for airborne diseases management in a deployable treatment facility.

Abstract

Objective: To assess whether wind-driven natural ventilation in the Infectious Diseases Treatment Module (IDTM) can achieve ventilation performance consistent with airborne precaution requirements [160 liters per second (L/s)] and to estimate associated pathogen-specific infection risks.

Methods: An experimental campaign of air velocity measurements and CO₂ decays were conducted to validate the developed computational fluid dynamics (CFD) model. The validated CFD model simulated wind-driven natural ventilation (1-4 m/s) for an L-shaped IDTM configuration under four structural scenarios defined by the presence or absence of patient porches and mosquito nets. Airborne infection risk was estimated using a Wells-Riley quanta-based model for seven representative airborne pathogens under short-duration healthcare worker exposure and prolonged patient co-exposure.

Results: Ventilation performance varied widely based on wind speed and structural configuration. Airflow ranged from 7 L/s in the most restricted configuration (porch and mosquito nets present at 1 m/s) to over 3,100 L/s when mosquito nets were removed at 4 m/s.When mapped to infection-risk estimates, ventilation rates at 160 L/s substantially reduced short-duration healthcare worker infection risk for all pathogens (≤1%), whereas prolonged co-exposure remained associated with high risk for high-emission pathogens despite high ventilation.

Conclusion: Under favorable wind conditions and optimized configurations, the IDTM can achieve ventilation rates consistent with the 160 L/s recommendation for airborne precautions. While this provides substantial protection for healthcare workers, individual-room isolation remains essential for patient management. Operationally, removing window-mounted nets is the most effective way to ensure safety targets are met; hybrid ventilation measures should be considered during low-wind conditions.