Pollutions

These are materials which are in liquid, solid, or gaseous form that pollute the environment by lowering or reducing its usefulness value or quality.

Generally, pollutants can be grouped into four types which are solid, liquid, gaseous and radioactive materials. However, all these are grouped into persistent and non-persistent pollutants.

At national level pollution is categorized into four main types. These are

1. Land pollution
2. Water pollution
3. Air pollution
4. Noise pollution

This refers to the disposal or introduction of unwanted substances on the soil which may make land less useful for supporting living organisms both vegetation and animals. Soil can be polluted by liquid, solid, gaseous or radioactive materials.

Causes of land pollution

1. Introduction or disposal of industrial wastes from industrial activities.
2. Disposal of domestic wastes on the land. This waste includes garbage and other waste products.
3. Excessive use of chemical sprays and industrial fertilizers in agricultural activities.
4. Falling of acidic rain on the land which adds acidic gases on the soil.
5. Natural calamities such as soil erosion, earthquakes, mass wasting and weathering.

Effects of land pollution

1. Land pollution may cause death of soil living organisms which may cause poor soil, decomposition and low fertility.
2. Land pollution may cause water pollution if there is surface run off in polluted soil to the water bodies.
3. Excessive land pollution may cause eruption of diseases such as cholera which may kill many people.
4. Sometimes it may cause migration of people because people may abandon the polluted soil.
5. Emission of bad smell which reduces comfort to the people.

This is the disposal or discharge or contamination of water by undesirable solid, liquid, gaseous or radioactive materials into water bodies like sea, ocean, rivers, swamp, ponds and springs.

Causes of water pollution

1. Discharge of industrial wastes into water bodies due to industrial activities. This mostly occurs in urban areas like Dar-es-salaam, due to the presence of many industries affected much by this factor.
2. Disposal of domestic waste in water bodies. This occurs in water bodies surrounded by human settlement, so people of that area may pollute water bodies.
3. Oil spillage in water bodies like oceans, due to leakage of oil ship (tanker) and leakage of oil tank and pipe near or in the water bodies.
4. Illegal and excessive fishing activities in water bodies, for example fishing methods like use of poisons or explosives in getting fish.
5. Disposal of radioactive and other chemicals in water bodies due to testing of atomic bombs.

Effects of water pollution

1. It may kill aquatic living organisms like fish and vegetation.
2. It may cause occurrence of diseases and death of many people in an area, due to the use of contaminated water e.g. cholera.
3. It may cause irritation of human skin due to skin cancer by washing their bodies in polluted water and reduce comfortability to the people.
4. It may cause decline of tourism activities e.g beach tourism.

This is the pollution caused by introduction or emission of unwanted substances in the atmosphere which occurs mostly in urban areas.

Causes of air pollution

1. Emission of gases in atmosphere due to excessive use of fossil fuel such as charcoal, firewood which lead to emission of oxidized carbon dioxide, Nitrogen oxide in atmosphere.
2. Emission of dust and soot from mining activities which may pollute atmosphere.
3. Emission of smoke and gases from volcanic eruption. This means volcanoes may emit gases and other waste in atmosphere which may cause air pollution.
4. Construction activities which may cause emission of dust in the air.
5. Emission of fumes and gases like Nitrogen gases from a moving vehicle such as aeroplanes, cars, train due to burning of fuel.

Effects of air pollution

1. Air pollution may cause destruction of ozone layer due to the emission of gases such as chlorofluorocarbon (CFCs) and Nitrogen oxide which may cause depletion of ozone layer.
2. Air pollution may cause global warming in an area. This is an increase in average temperature on the earth's surface due to ozone layer depletion and greenhouse effects which may cause sun rays to penetrate direct on the earth's surface but be protected from being reflected back.
3. It may cause occurrence of acidic rain. This occurs when the emitted gases in atmosphere (acidic gas) mix with water droplets which may cause acidic rainfall.
4. It may cause death of both plants and animals due to excessive rise in temperature (global warming) and acidic rainfall which may cause death of living organisms.

Noise is any disorganized sound or unpleasant sound to people's ear.

Noise pollution is the emission of unpleasant sound or undesirable noise in the atmosphere which may harm people by causing trouble in people's ears.

Causes of noise pollution

1. Excessive or unpleasant noise from industrial activities such as iron and steel industries.
2. Noise emission from quarrying and mining activities. This noise is emitted from machines and explosives.
3. Noise emission from music halls. This occurs for those halls which have no soundproof mechanism.
4. Excessive noise from moving vehicles. These vehicles include motorcycles, cars and aeroplanes.
5. Noise emitted from natural disasters like thunderstorms.
6. Construction activities which cause eruption of unpleasant sound like road construction.

Effects of noise pollution

Noise pollution may cause the following effects in a country

1. It may affect human health e.g. destruction of eardrums to the people.
2. It may affect people's comfort, for example people may fail to sleep at night or day due to unpleasant sound.
3. It may disturb wild animals' habitats which may cause the migration of animals and birds from one place to another.
4. Excessive noise may cause skin irritation and headache to the people.

There are several methods used by local or national government in controlling pollution and effects of pollution. All these approaches are grouped into

1. Pollution taxes
2. Quotas on pollution (tradable emission allowance)
3. Direct control

Other measures

Pollution taxes or tariffs

These are special taxes imposed to those who pollute environment. This tax is imposed on production or consumption which cause pollution or products if considered as a source of pollution in environment.

A pollution tax which is considered as an advantage is that it reduces pollution to the socially optimal level would be set at a level that pollution occurs at the level where it benefits to the society (greater production) exceeds the cost.

Quotas on pollution (tradable emission allowance)

It is advocated that pollution reductions should be achieved by way of tradable emissions permits which freely traded may ensure reduction in pollution are achieved at least cost. In theory, tradable quotas are allowed, then firms would reduce cost and its own pollution load only if doing so would reduce cost, less than paying someone else to make same reduction. Therefore firms may change technique or inputs which may be able to reduce cost.

Direct control

This is the total ban policy whereby government use direct method of controlling environmental pollution by establishing strict laws and policy which restricts environmental pollution.

1. Provision of environmental education to the people on the importance/significance of environment and ways of environment conservation.
2. Government should establish laws and policies which completely ban and control pollution and source of pollution. In these methods government may restrict raw materials which cause pollution e.g. the use of firewood and use of soft plastic bags.
3. Introduction and the use of methods of conserving environment like the use of recycling of wastes and anti-pollution equipment i.e. production process such as sound proof, coal burning power station, desulphurisation plants.
4. Government and NGOs should advise producers to produce and market environmental friendly products and making assessment on impact of product/production on environment so as to make right decision on either to allow or restrict investment.
5. The use of improved state of technology in production. This means producers should use efficient technology and technique which minimize pollution on the environment.
6. Population control policy. Government and NGOs should promote on reduction of population because rapid population growth is the main cause of pollution especially in urban areas like Dar-es-salaam.
7. Efficient town planning with good sewage system and dumping areas and provision of incentives schemes. i.e. government should provide incentives and awards to those who make proper environmental conservation so as to encourage others.
8. Better defined property rights. According to Coase theorem, state that assigning property right will lead to an optimal solution, regardless of who receive them if transaction costs are retrieval and the parties negotiating are limited. Because property rights identify who has a right to clean the environment or factory has a right to pollute, then either factory could pay factory not to pollute environment.