Asthma is a respiratory disease concerned with

Smoking leads to ................. in the blood.

Which of the following is a chronic respiratory disorder?

$A$: 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.

Emphysema disease is caused by

When the blood contains a high percentage of $CO_2$ and a very low percentage of $O_2$,the breathing stops and the person becomes unconscious. This condition is known as: