3.2.9 Pollution & Smoking

Effects of Pollution on the Gas Exchange System:

1. Particulate Matter (PM):

• Tiny particles (e.g., from vehicle emissions) can be inhaled and lodge in the lungs.
• Causes inflammation, reduces elasticity of lung tissue, and increases the risk of respiratory diseases.

2. Nitrogen Oxides (NOx):

• Found in polluted air; irritates the airways and exacerbates conditions like asthma.

3. Sulphur Dioxide (SO₂):

• Causes airway inflammation, leading to bronchitis and reduced lung function.

4. Ozone (O₃):

• A major component of smog; damages alveolar walls and reduces lung capacity.

5. Chronic Exposure:

• Long-term exposure to polluted air increases the risk of developing chronic obstructive pulmonary disease (COPD) and lung cancer.

Effects of Smoking on the Gas Exchange System:

Smoking introduces harmful substances into the lungs, damaging the alveoli, airways, and cilia. Key components of cigarette smoke and their effects include:

6. Tar:

• A sticky substance that coats the airways, reducing gas exchange efficiency.
• Paralyses cilia, preventing the removal of mucus and debris.
• Increases the risk of lung cancer by containing carcinogens.

7. Carbon Monoxide (CO):

• Binds to haemoglobin in red blood cells, reducing their oxygen-carrying capacity.
• Leads to hypoxia (low oxygen levels in tissues), causing fatigue and breathlessness.

8. Nicotine:

• A stimulant that increases heart rate and narrows blood vessels, reducing oxygen delivery to tissues.

9. Irritants:

• Cause inflammation of the airways, leading to conditions like chronic bronchitis.

10. Destruction of Elastic Fibres:

• In conditions like emphysema, smoking damages elastic fibres in the alveolar walls, reducing lung recoil and trapping air in the lungs.

Diseases Associated with Smoking:

11. Chronic Bronchitis:

• Inflammation of the bronchi, leading to excessive mucus production and persistent coughing.
• Airflow is obstructed, reducing oxygen intake.

12. Emphysema:

• Destruction of alveoli reduces the surface area for gas exchange.
• Lungs lose elasticity, making it difficult to exhale fully.

13. Lung Cancer:

• Smoking introduces carcinogens that mutate lung cells, leading to uncontrolled growth and tumour formation.
• Symptoms include persistent cough, chest pain, and breathlessness.

14. Coronary Heart Disease (CHD):

• Smoking contributes to the narrowing of blood vessels and increases the risk of heart attacks and strokes.

Prevention and Mitigation:

15. Reducing Pollution:

• Use cleaner energy sources to minimise emissions of harmful gases.
• Implement policies to reduce vehicle emissions and industrial pollutants.

16. Quitting Smoking:

• Reduces the risk of lung diseases and improves overall lung function.
• Support includes nicotine replacement therapy, medications, and counselling.

17. Protective Measures:

• Wear masks in areas with high pollution.
• Avoid smoking or exposure to second-hand smoke.

Key Points to Remember:

Factor	Effect on Gas Exchange	Associated Diseases
Pollution	Inflammation of airways, damage to alveoli.	Asthma, COPD, bronchitis, lung cancer.
Smoking	Reduced oxygen transport, destruction of alveoli.	Chronic bronchitis, emphysema, lung cancer, CHD.