CBSE Class 10 Answered

Other causes of breathing difficulties include:

• Allergies and anaphylactic reaction

• Anxiety attacks or panic attacks

• Certain cancers, such as leukemia

• Heart conditions, such as heart attack, pericarditis, congestive heart failure etc.

• High altitudes

• Hyperventilation

• Obesity or poor physical shape etc.

Due to smoking, several toxins enter the lungs and deteriorate them. A non-smoker’s lungs is healthily pink, while the lungs of smokers come out as dark red, brown, or even black spots. Smoking also causes lungs to exert more effort in certain strenuous activities. 

Smoker’s lungs are also polluted by the tar that comes from cigars and cigarettes. This tar gets stuck in the bronchial tubes thus causing them to get clogged. The lungs, however, try to rid the bronchial tubes of tar by stimulating coughs, although nicotine is the main problem. It upsets the delicate balance of gas exchange. The now-constricted blood cells have trouble picking up and dropping off carbon dioxide and oxygen respectively.