Which statement correctly contrasts airborne and droplet transmission?

• A. Droplet transmissions involve particles smaller than 1 micron
• B. Airborne transmissions do not involve any particles
• C. Airborne involves <5 microns and can remain airborne for hours; Droplet involves >5 microns and does not stay airborne for long
• D. Airborne and droplet transmissions are the same mechanism

Answer: (C)

Understanding how infections spread via airborne versus droplet routes hinges on particle size and how long those particles stay in the air. Airborne transmission uses small particles, typically under about 5 microns, that can remain suspended in air for hours and travel with air currents. Droplet transmission involves larger particles, generally over about 5 microns, which settle quickly and usually travel only short distances, requiring close contact for spread. That difference—small, long-lasting aerosols vs larger, short-range droplets—is what the statement correctly captures.

Why the other ideas don’t fit: droplets aren’t confined to particles under 1 micron, and airborne transmission does involve particles (aerosols); the two are not the same mechanism.