Burning of fossils fuels occurs in electrical power plants, factories, mining and metal extraction industries, incinerator, motor vehicles, aircraft, ships and home furnaces. The pollutants released include various gases, smoke, soot, dust and grit.
Oxides of Carbon:
Carbon monoxide is formed whenever fuel is burned incompletely. The motor vehicle exhaust is the main source of this pollutant. Thus, the air in busy or industrial towns and cities.
Carbon monoxide is a poisonous gas. It combines readily with haemoglobin, the oxygen carrying pigment in blood, to form a stable compound. If carbon monoxide is present in inhaled air, it competes with oxygen for the haemoglobin. As a result, the blood carried less oxygen to the body cells.
Note : Oxygen is essential for cellular respiration, the energy releasing process that operates continuously in all living cells. Our brain cells can only live for a few minutes in the absence of oxygen.
In low concentration, carbon monoxide causes dizziness, headache, nausea and tiredness. If inhaled for long periods, even at low concentrations, it can cause brain damage. At concentrations, it can cause unconsciousness and even death.
Carbon dioxide is Prof when fuels and other carbon compounds are burned in plenty of air. Decay and respiration are natural processes that release this gas into the air. Scientists feat that the high concentration of carbon dioxide in the atmosphere may give rise to the green house effect.
Sulphur dioxide :
Most fossil fuels contains sulphur, especially the low grade petroleum fuels and coal. When they are burnt, they produce sulphur dioxide. The main sources of this gas are the electrical power stations, factories and mining centres that use coal as fuel since it is cheap. Thud , the sir around mining towns has higher concentration of sulphur dioxide.
Sulphur dioxide is an acidic poisonous gas. It readily dissolves in most air to form an acid. When such air is inhaled, this acid irritates and damages the sensitive lining of our eyes, air passages and lungs. Prolonged exposure to air containing this pollutant may be linked to lung diseases, cancer and heart attacks. Lichens are especially sensitive to the presence of sulphur dioxide. Their growth is greatly reduced in regions where the air is polluted with this gas.
Sulphur dioxide dissolves in rain water, giving rise to acid rain. When avid rain falls on vegetation, it reduced their growth and damages their leaves. When it falls on buildings and metallic structures, it dissolves them. Acid rain also dissolved the aluminium salts in soil, causing them to build up to toxic levels in underground water supplies. This affects our source of drinking water. When this water flows into pounds and lakes, it slowly destroys the plant and animal life in them.
Note: the pH of unpolluted rainwater is between 5•0 and 5•6. Acidic rainwater may have a pH a round 4.
Oxides of nitrogen:
Oxides of nitrogen are formed when coal is burned. They are also found in the exhaust of motor vehicles.
Oxides of nitrogen are poisonous and acidic. They too dissolve in rain water to give rise to acid rain.
Like sulphur dioxide, they damage our air passages and lungs; have a toxic effect on vegetation; and corrode buildings and metal structures. In addition, they undergo changes in the atmosphere which lead to the formation of photochemical smog.
Hydrogen sulphide:
This gas is produced by industrial processes such as those associated with coal mining and crude oil refining. It is a poison and mildly acidic gas.
Hydrocarbons:
Hydrocarbons are released into the air when volatile fuels evaporate from storage tanks. They also found in exhaust of motor vehicles when fuel is burnt incompletely.
Many hydrocarbons are believed to cause cancer. As already discussed, they lead to the formation of photochemical smog.
Solid pollutants:
These include smoke, soot and dust. These are emitted by motor vehicles, industrial plants, electric power stations and incinerator. When inhaler , they irritate the sensitive mucous lining of the nose, throat and air passages and damage the delicate gaseous exchange surfaces in our lungs.
A very poisonous solid pollutant is lead dust which is emitted in the exhaust of motor cars using leaded petrol. Lead dust can cause anaemia and brain damage in children, and injury to the nervous system in adults. The leads that is inhaled can accumulate in the body without being excreted. Over a long period, the amounts of lead in the body can build up to levels that can cause poisoning. Another similar poison is mercury which is produced when coal and garbage are burnt.
Solid pollutants are damage vegetation, cause the formation of smog and affect the weather.
