Environmental pollution has become a worldwide problem as it may adversely affect human health

Nov 24 - Dec 07, 2003



Pollution is the addition to the environment of any substance or energy form (e.g. heat, sound) at a rate that results in higher than natural concentrations of that substance or energy form. The high rates of urbanization, industrialization, heavy transportation and deforestation have produced tremendous environmental problems around the globe in air, water and soil media. Any undesirable change in physiochemical or biological characteristics of our air, land and water will severely affect human life. Among the various types of pollution water pollution by waste discharge through various types of industries located around the big cities of a country is the main cause of deteriorating aquatic and agroecosystems. Waste products of different industries pass through the drains, which often meet together at a certain place to form a big drain. These waste-water products ultimately fall into river water such river water is used for irrigation of crops, vegetables, etc. After using these vegetables/crops for eating affects the biological systems of our daily life.

Environmental pollution has become a worldwide problem as it may adversely affect human health. This problem has been created by man himself as a result of indiscriminate release of harmful substances and toxic heavy metals into the environment from various socio-economic development activities such as industrial, agricultural, which may adversely affect the quality of air, water and food resources, these toxic chemicals may find their way to living organisms and human body through food chain and may induce various metabolic disorders.

Pollutions commonly are classified according to the part of the environment primarily affected air, water or land. Subgroups depend on characteristics of the pollutants themselves: chemical, physical, thermal and others. Many pollutants affect more than one resource. Some pollutants such as noise produce only local and short-lived effects. Other such as smelter slag, affect limited areas but may persist for many years. Some substances such as radioactive dusts and certain pesticides (e.g. DDT), disperse readily and have become virtually worldwide in distribution. Such pollutants, which include many chlorinated hydrocarbon insecticides and several toxic mercury compounds may enter biological food chains through microorganisms. Like the industrialized countries of the world, the problem of pollution has also become serious in the industrialized cities of Pakistan. In area, where industries have been concentrated, the ill effects of pollution on surrounding vegetations and vertebrates are becoming obvious. This is especially so in the industrialized areas of Karachi, Lahore, Faisalabad, Peshawar, Multan, Hyderabad, etc. The drinking water in the nearby villages/Goths have become non-potable.

The most important pollutants, which have greatly threatened to affect the quality of environment and ultimately our daily life are: a) Corrosive and toxic gases, cyclic and fluorinated hydrocarbons present in atmospheric air; b) agric-chemical, industrial and other chemicals; c) heavy metals, industrial and municipal wastes; d) radioactive substances and radiations; e) agricultural insecticide/pesticides.

The corrosive gasses are present in the air. Therefore, the air pollution is generally associated with all the activities of humans. It is becoming a serious problem in the present day human lives. Air pollution is one of our most serious environmental problems. Salts from oceans/seas, gases and debris from erupted volcanoes and cosmic dust are nature's pollutants. Dust storms and forest fire add more debris to the atmosphere. The advent of industrial era in 19th century has significantly increased the air pollution. The invention of automobiles by man has become our worst air. Air pollution that is due to pollute present and foreign substances in air, affects the quality and concentration of air ingredients. The air consists of gases nitrogen 78.1%, oxygen 20.9%, argon 0.9% and the rest 0.1%, which includes toxic gases and aerosol particles on which bacteria, organic and inorganic pollutants reside. These particles more with the wind and are transported from one place to another and ultimately settle on the ground or washed out by the rain water.

Common air pollutants are gases like carbon dioxide (CO2), carbon monoxide (CO), sulphur dioxide (SO2), nitrous oxide (N2O), etc., particulate materials consisting of polynuclear aromatic hydrocarbons and trace inorganic elements mainly lead, mercury, beryllium, arsenic, antimony, nickle, chromium, cadmium, etc. Main sources are fossil fuels, burning coal, motor vehicle exhaust, industrial emission, and atmospheric nuclear tests, which cause radioactive pollution. The activities of air pollutants in the environment and ultimately their effects a human health are given below:

CARBON DIOXIDE (CO2): The concentration of carbon dioxide in the atmosphere has risen from 315 mg/litre in 1958 to the present level of 360 mg/litre. This indicates that composition of CO2 in the atmosphere is increasing day by day. The increase in CO2 level could affect the growth and development of plants. At high concentration, it inhibits enzymes and reduces photosynthesis. As a consequence of the considerable increase in human and global consumption of fossil fuels amounts to 4.5 billion tons of coal, 3.2 billion tons of oil and 17.5 billion cubic feet of natural gas, which together release 24 billion tons of CO2 and Pakistan uses 3.5 million tons of coal, 13.2 million tons of oil and 551 cubic ft. of gas amounting to 106 million tons of CO2 into the atmosphere annually, which can play a major role in the heating of the earth's surface. The annual emission of CO2 in Pakistan about 106 million tons. As the world warms up, the seas would rise by 2.5 inches a decade on the average and are infected to swell by as much as 3 ft. by the year 2100, affecting ahout 224 x 103 miles of the world's coastline. This increase in the average temperature of the planet, therefore has the potential of changing the overall pattern of food production globally.

CARBON MONOXIDE (CO): It constitutes about 55 per cent of the pollution made by humans through vehicles. It is very poisonous to humans and its toxic level may cause headache, dizziness. It is present in the atmosphere in the range of 0.00001 per cent by volume. The annual emission of CO in Pakistan is about 2.858 million tons.

HYDROCARBON (CH4): The hydrocarbons are produced by automobiles and petroleum industry. It is also present in cigarette smoke that causes lung cancer. They also cause death of animals and birds. The emission from diesel and gasoline comprise mainly of hydrocarbon gas.

OZONE (O3): Ozone is a highly activate form of oxygen that has equally high oxidizing power. Ozone is always present in the earth atmosphere in trace quantities. In the stratosphere (altitude range 15-50 kms.), there is a concentration of a special form of oxygen called "ozone". The role of high concentration of ozone in the stratosphere is vital as much as it acts as a very effective filter for absorbing ultra violet rays, which are integral component of sunlight. In stratosphere, it acts as a shielding lay to protect us from the effects of ultraviolet rays, whereas on earth surface, it acts as our enemy. Without adequate population of ozone there would be an increase in the intensity of ultraviolet rays falling on the surface of the earth resulting in very serious health hazard to human beings in the form of skin cancer. Its level even at 10 ppm causes headaches, eye irritation coughing and chest discomfort. High concentration of ozone in the troposphere (altitude range 0-15 kms.) has been reported to have caused reduction in crop yields by 10-45 per cent depending on the relative humidity, concentration of ozone duration of exposure of the crops to the ozone gas. On an international scale, the crop losses on account of elevated levels of ozone may run into several billion dollars each year.



Excessive release of chlorine, freon and nitrogen oxide from various activities of man result in reduction of population of ozone at high altitudes. Aerosols containing highly reactive chlorofluoromethanes also destroys the ozone layer and increases the chances of skin cancer. Destruction of ozone layer will increase the temperature of the earth. Rise in temperature will cause damage to the crop production because the growing of crops mainly depends on temperature. Thus, increase in temperature of the earth has the potential of changing the overall pattern of food production globally.

NITROUS OXIDES (N2O): Nitrogenous gases are also the principal source of pollution, which come through automobiles. Its greatest harm is when it forms a photochemical smog in subtropical areas with heavy traffic at times, when air is stagnant. Nitrous oxide, which emits from motorized vehicles shows about 0.33 ppm in the atmosphere.

SULPHUR DIOXIDE (SO2): Sulphur in the atmosphere is present in gaseous, liquid and solid gases. The primary gaseous sulphur compounds in the atmosphere are SO2 and H2S. The pollutant sources of 5 compounds are primarily accounted by combustion sources using coaler heavy fuel oil, petroleum refining operations, smelting and refining of the nonferrous ones of copper, lead, zinc and nickel. Global SO2 emission estimate is about 215 x 106 tons/year. Sulphur dioxide is a harmful gas. This gas affects the leaves of most plants at the concentration of 0.5 ppm or less in air. In atmosphere, SO2 oxidizes readily to form SO3, which in presence of water becomes sulphuric acid (H2SO4). It can cause acid rainfall, when associated with smog. This acid rainfall causes damage to crops on the earth. It has been observed that dry deposition of sulphates and sulphur dioxide on buildings also are harmful as acid rain.

HEAVY METALS: Heavy metals, which are released into the environmental from the industrial, agricultural and other activities constitute another important group of pollutants. The elements cadmium (Cd), arsenic (As), chromium (Cr), mercury (Hg), lead (Pb), titanium (Ti) and toxic can be tolerated only at very low levels in the biochemical systems. Three elements Hg, Cd and Pb are highly toxic and constitute a serious hazard for man and other living organisms. Being biologically non-degradable, these metals accumulate in vital human organs such as brain, nerve system, kidney, liver, intestinal tract, lungs and adversely affect the biochemical processes. Lead and Cd are also deposited in bones and under certain physiological conditions can become remobilized causing serious damage. Toxic metals can also affect carriers of the genetic code by farming chelates with the nucleic acids thereby causing infidelities in the transmission of genetic information. Accumulation of Cd in kidneys causes abnormal excretion of low molecular weight proteins in urine. Lead adsorption increases Fe deficiency and inhibits all enzymatic steps. Barium (Br) damages heart tissues. Increased lead exposure causes disturbance in functioning of kidney muscles and blood. It may produce neurotic effects, dullness, restlessness, poor attention span, headache and memory loss. Environmental pollution in Pakistan is growing at a faster rate and is a serious threat to its economy as well as human health.



PESTICIDES: Organic chemicals, especially the pesticides and detergents pose a serious threat to human health as these have been introduced into the environment during the last few decades and to which mankind has no previous exposure. Further, most of these chemicals do not degrade easily and progressively accumulate in the environment from there they ind their way to the human body through the food chain. The annual consumption of various pesticides in Pakistan has increased from 906 m.ton in 1981 to more than 1200 m.ton in 1996. Commonly used pesticides are DDT, DDD, DDE, PCB, Y-BHC, aldrin, endrin, dieldrin, endosulphan, chlordane, malathion, parathion, phorate, durban, diazinon, benomyl, aldicarb, aminocarb, chlopyrifos, carboryl, carbofuron, schardan, phosphomidan, aldicarb, propoxur, heptachlor, etc.

PARTICULATE MATTERS: Particulate matter is an important source of pollutants, which is generated by many ways inside the building such as building and furnishing materials, office equipment and in and out movement of people. Airborne particulates may contain organic compounds, traces of metals, nitrates, sulphates, etc., which when inhaled may affect human health. The health effects of particulates depend upon the size, shape, density and reactivity of particles as well as on the respiration rate and quantity of intake. Air particles with a nominal aerodynamic diameter of 10 micrometer (um) or less the ones, which penetrate into the respiratory system. Equipment used in the office also affects the quality of indoor air. Photocopying machines, fax machines, computer workstations, laser printers, adhesive tapes, glove correction fluids and marker pens are sources of volatile organic compounds, ozones and particulates.

EFFECTS OF NUCLEAR TEST: After the nuclear weapon test, a large number of pollutants such as carbon monoxide, hydrocarbon, nitrogen oxides, sulphur oxides, heavy metals, acids, and variety of other toxic chemicals could be released in the atmosphere. They will affect the environment and deplete the ozone layer. World agriculture and major ecosystems such as forests, grass lands and marine system would be severely disturbed, which in turn, would affect their plants and animals. There are herbicides, acaricides and fungicides, which also affect the environment.


The control of pollution has provided many of the most difficult economic, legislative and administrative questions of the 20th century. Many serious pollutants are closely and fundamentally found to vital agricultural or industrial systems or products. A clean and safe environment is essential for our survival. Trees and plants may play very important role in cleaning air and beautifying the physical environment.