Definition and Importance:

Ventilation is the process of supplying fresh air to an indoor space and removing stale air. It plays a critical role in controlling the spread of airborne pathogens, such as Mycobacterium tuberculosis, influenza viruses, and SARS-CoV-2. Proper ventilation dilutes and removes infectious aerosols, reducing the risk of transmission.

Types of Ventilation:

• Natural Ventilation: Utilizes natural forces like wind and thermal buoyancy to move air through openings such as windows, doors, and vents. It is cost-effective, requires minimal maintenance, and is particularly suitable for resource-limited settings and tropical climates. However, its effectiveness depends on building design and environmental conditions.

• Mechanical Ventilation: Employs mechanical systems like fans and ductwork to control airflow. It provides consistent ventilation regardless of external conditions but requires energy and regular maintenance.

• Hybrid (Mixed-Mode) Ventilation: Combines natural and mechanical methods to optimize air quality and energy efficiency.

Design Considerations:

Effective ventilation design should ensure adequate air changes per hour (ACH) to dilute contaminants. For example, the CDC recommends a minimum of 12 ACH for airborne infection isolation rooms. Designs should also prevent air stagnation and ensure airflow from clean to less clean areas to minimize cross-contamination.