The respiratory system is exposed to the outside air with every breath, so it is easily harmed by smoke, dust and airborne microbes.
Effects of smoking
Cigarette smoke contains several harmful substances:
- Nicotine — an addictive drug that raises heart rate and blood pressure and makes the smoker crave more.
- Tar — a sticky, carcinogenic substance that collects in the lungs and can cause lung cancer. It also paralyses the cilia that clean the airways.
- Carbon monoxide — binds to haemoglobin more strongly than oxygen, forming carboxyhaemoglobin and reducing the oxygen the blood can carry.
Remember
The single most effective way to prevent smoking-related lung disease is not to smoke, and to avoid second-hand smoke.
Common respiratory diseases
- Asthma — the bronchioles narrow and become inflamed, often triggered by allergens, making breathing difficult.
- Chronic bronchitis — long-term inflammation of the bronchi with excess mucus and a persistent cough.
- Emphysema — the walls of the alveoli break down, reducing the surface area for gas exchange and leaving the person breathless.
- Pneumonia — an infection in which the alveoli fill with fluid, reducing gas exchange.
- Tuberculosis (TB) — a bacterial infection of the lungs spread through the air.
Air pollution
Smoke, dust and haze irritate the airways and worsen asthma and infections. During haze, people are advised to stay indoors and wear masks.
Keeping the respiratory system healthy
Many of these problems can be prevented. Not smoking and avoiding second-hand smoke removes the biggest risk, since passive smoke exposes non-smokers to the same harmful chemicals. Regular exercise, clean air and good ventilation all help. Persistent coughing, breathlessness or repeated chest infections are warning signs that should be checked by a doctor, as early treatment greatly improves recovery.
Example
A long-term smoker becomes breathless climbing stairs because emphysema has destroyed alveoli, leaving a smaller surface for oxygen to enter the blood.