What is a consequence of PM deposition in the alveoli forming a barrier?

What is a consequence of PM deposition in the alveoli forming a barrier?

• A. Increased oxygen transfer
• B. No effect
• C. Immediate lung cancer
• D. Reduced blood-oxygen saturation due to barrier formation

Answer: (D)

When particles deposit in the alveoli, they can trigger inflammation and remodeling that thickens the alveolar-capillary barrier. Gas exchange relies on diffusion across a very thin membrane, so increasing the diffusion distance and reducing the effective surface area slows oxygen transfer from air into the blood. As a result, arterial oxygen saturation drops when this barrier forms. This isn’t an immediate cancer outcome, and it isn’t a situation of no effect or of increased oxygen transfer; the barrier actually impedes diffusion, lowering oxygenation.

When particles deposit in the alveoli, they can trigger inflammation and remodeling that thickens the alveolar-capillary barrier. Gas exchange relies on diffusion across a very thin membrane, so increasing the diffusion distance and reducing the effective surface area slows oxygen transfer from air into the blood. As a result, arterial oxygen saturation drops when this barrier forms. This isn’t an immediate cancer outcome, and it isn’t a situation of no effect or of increased oxygen transfer; the barrier actually impedes diffusion, lowering oxygenation.