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

Area of Science:

• Environmental Engineering
• Infectious Disease Control
• Building Science

Background:

• Airborne precautions are critical in healthcare settings to prevent pathogen transmission.
• Natural ventilation strategies are being explored as sustainable alternatives for infection control.
• The Infectious Diseases Treatment Module (IDTM) requires specific ventilation rates (160 L/s) for airborne infection risk mitigation.

Purpose of the Study:

• To evaluate the efficacy of wind-driven natural ventilation in IDTMs for meeting airborne precaution standards.
• To assess the impact of structural configurations on ventilation performance.
• To estimate pathogen-specific infection risks under various ventilation scenarios.

Main Methods:

• Computational fluid dynamics (CFD) modeling was employed, validated by experimental air velocity and CO2 decay measurements.
• Simulations covered wind speeds from 1-4 m/s and four structural scenarios (varying porch and mosquito net presence).
• Airborne infection risk was quantified using the Wells-Riley model for seven pathogens, considering healthcare worker and patient exposure.

Main Results:

• Ventilation rates varied significantly, from 7 L/s to over 3,100 L/s, depending on wind speed and structural elements.
• Achieving 160 L/s substantially reduced short-term healthcare worker infection risk (≤1%) for all tested pathogens.
• Prolonged patient co-exposure remained a high risk for high-emission pathogens, even with high ventilation rates.

Conclusions:

• Optimized IDTM configurations and favorable wind conditions can achieve the recommended 160 L/s for airborne precautions.
• Removing window-mounted mosquito nets is the most effective modification to meet safety targets.
• While natural ventilation offers significant protection for healthcare workers, isolation remains crucial for patients, and hybrid systems may be needed for low-wind conditions.