Which statement best describes how smaller PM particles behave in the respiratory system?

Which statement best describes how smaller PM particles behave in the respiratory system?

• A. They travel farther into the respiratory system
• B. They stay in the upper airways
• C. They are expelled before entering the lungs
• D. They immediately dissolve in blood

Answer: (A)

Smaller PM particles travel farther into the lungs because their tiny size allows them to follow the air flow all the way into the distal airways and alveolar regions. Large particles have more inertia and tend to collide with and deposit in the nose and upper airways, while fine particles can bypass those filters and deposit deeper where diffusion and slow sedimentation become the primary deposition mechanisms. So, the depth of penetration increases as particle size decreases, making it possible for these smaller particles to reach the deeper parts of the respiratory system. They aren’t typically expelled before reaching the lungs, and while some may dissolve or interact with blood or tissues in the alveolar region, immediate dissolution is not guaranteed and depends on the particle’s composition.

Smaller PM particles travel farther into the lungs because their tiny size allows them to follow the air flow all the way into the distal airways and alveolar regions. Large particles have more inertia and tend to collide with and deposit in the nose and upper airways, while fine particles can bypass those filters and deposit deeper where diffusion and slow sedimentation become the primary deposition mechanisms. So, the depth of penetration increases as particle size decreases, making it possible for these smaller particles to reach the deeper parts of the respiratory system. They aren’t typically expelled before reaching the lungs, and while some may dissolve or interact with blood or tissues in the alveolar region, immediate dissolution is not guaranteed and depends on the particle’s composition.