Tobacco smoke contains carbon monoxide,which

Which of the following is associated with an occupational hazard?

The state during which the respiratory centre is inhibited is termed as:

At what $pCO_2$ level may death occur?

Name the respiratory disorder in which the alveolar surface area involved in gas exchange is significantly reduced due to damage in the alveolar walls.

$A$: Asthmatic patients use bronchodilator drugs as well as inhalers for symptomatic relief.
$R$: Asthma is characterized by the spasm of smooth muscles in the wall of bronchioles due to allergens.