How long can airborne particulates last?

• A. Minutes only
• B. Hours in the air
• C. Seconds
• D. Days

Answer: (B)

Airborne particulates can stay in the air for hours because the smallest droplets (aerosols) have a very low settling rate and can be carried by air currents. Unlike larger droplets that quickly fall out of the air within seconds to minutes, these tiny particles can remain suspended and recirculate in a room, especially if ventilation is limited or there’s ongoing generation (talking, coughing). So in typical indoor settings, aerosols can persist for hours, with the exact duration influenced by particle size and how well the space is ventilated. Days in the air would require unusual, sustained conditions, so hours is the most accurate general answer.