Which chronic disorder is characterized by damage to the alveolar walls,leading to a decrease in the respiratory surface area,and is primarily caused by cigarette smoking?

In severe cases of which of the following diseases may the lips and fingernails turn gray to bluish in color?

Which of the following is associated with an occupational hazard?

If a person stays on Mount Everest for some days,what will happen to their red blood cells (RBCs)?

$A$: Emphysema is a chronic obstructive pulmonary disease,causing irreversible distension and loss of elasticity of the alveoli.
$R$: Emphysema is preventable if chronic exposure to smoke (cigarette and others) and pollutants is avoided.

The oxygen toxicity is related with