Air Pollution

It refers to the introduction of harmful substances (pollutants) in the air.

Sources and Causes of Air Pollution

1. Vehicle exhausts and industrial fumes

• Theses contains substances like asbestos, mercury, carbon (II) oxide, Sulphur (IV) oxide, nitrogen oxides, carbon (IV) oxide.

2. Chlorofluorocarbons

• CFCs arise from chemicals such as pesticides, herbicides, insecticides, dry-cleaning solvents

3. Aerosols

• Such as those used in cosmetics, herbicides, pesticides, fire-fighting chemicals

4. Dusts

• Dust from quarries, road constructions, cement and lime factories.

5. Coal and charcoal burning

• Produce carbon (IV) oxide and carbon (II) oxide.

6. Lead

• From combustion of leaded petrol.

7. Natural gas

• From volcanic action and geothermal power station. This release hydrogen sulphide into the atmosphere.

Effects of Air Pollution

1. Dust

• Affects the respiratory system in animals.
• Irritate eyes
• Blocks the stomata of leaves, thus affecting transpiration and photosynthesis.

2. Chlorofluorocarbons

• Depletes the ozone layer leading to more penetration of ultra-violet rays which cause skin cancer and affects crops.
• Cause irritation of respiratory organs and poison water plants.

3. Lead

• Blocks the stomata of leaves thus affecting gaseous exchange, transpiration and photosynthesis.
• Affects the bloodstream and the nervous system leading to mental disorders and malfunctioning of body systems.

4. Carbon (IV) oxide and Carbon (II) oxide

• Both gases form smoke which affects visibility.
• Smoke blocks the stomata of leaves thus affecting transpiration and photosynthesis.
• Smoke causes eye irritation and breathing difficulties.
• CO₂ causes greenhouse effect which leads to global warming. This can cause the polar ice to melt raising ocean levels and cause flooding of lowlands.

5. Nitrogen (III) oxide and Nitrogen (IV) oxide

• Lead to formation of acid rain.
• Poisons animals’ respiratory systems.
• Nitrogen (IV) oxide is carcinogenic (can cause cancer).

6. Sulphur dioxide

• Causes bronchitis, pneumonia and heart failure.
• Interferes with gaseous exchange in animals.
• Leads to the formation of acid rain which lowers soil pH and affects plants.

7. Hydrogen sulphide

• It is poisonous to organisms and can cause deaths.

Control of Air Pollution

1. Using lead-free petroleum products and paints.
2. Banning discharge of toxic gases from industries and vehicles and smoking in public places.
3. Recycling CFCs in refrigerators.
4. Using absorbers and filters of toxic fumes in vehicles and industries.
5. Biological control of weeds, pests and diseases.
6. Encouraging the use of renewable sources of energy e.g. wind and solar energy.
7. Using catalytic converters to reduce the release of oxides of nitrogen and Sulphur.

• Improving engine designs so that CO is converted to CO₂.

8. Educating people on the need for sustainable environmental management.
9. The government should be a signatory to global treaties on environmental conservation.