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

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.