Airborne transmission refers to the spread of an infectious agent through which mechanism?

• A. Droplets or dust
• B. Contaminated water
• C. Direct contact with an infected person
• D. Contaminated surfaces

Answer: (A)

Airborne transmission means the infectious agent travels through the air and people can inhale it. Pathogens ride on particles that become suspended in the air, including larger droplets produced when someone speaks or coughs and smaller droplet nuclei or dust that can linger and move with air currents. Because the pathogen reaches the inhaled air directly, infection can happen without any contact with the source.

This differs from other routes: contaminated water implies the agent is transmitted through water, not through the air; direct contact requires physical touch with an infected person; contaminated surfaces involve touching a surface with the pathogen and then transferring it, rather than inhaling air carrying the agent.