Brownian diffusion primarily affects which particles?

Brownian diffusion primarily affects which particles?

• A. Very large particles
• B. Moderate-sized particles (1-5 μm)
• C. Very small particles
• D. Particles that are not aerosolized

Answer: (C)

Brownian diffusion is the random motion of particles caused by collisions with gas molecules. This jittering effect is most influential for very small particles because their tiny mass makes each collision cause a relatively large displacement, so they diffuse and deposit more readily. As particle size increases, inertia and gravity dominate, so diffusion plays a much smaller role for larger particles. Therefore, very small particles are primarily affected by Brownian diffusion.

Brownian diffusion is the random motion of particles caused by collisions with gas molecules. This jittering effect is most influential for very small particles because their tiny mass makes each collision cause a relatively large displacement, so they diffuse and deposit more readily. As particle size increases, inertia and gravity dominate, so diffusion plays a much smaller role for larger particles. Therefore, very small particles are primarily affected by Brownian diffusion.