It is an interesting fact that pollution is not always visible. A water reservoir like river or lake may seem clean but still be polluted. Air we breathe may contain air pollutants, which are not visible. Effects of pollution are as follows:
Effects of pollution on human health
1. Carbon monoxide (CO) emitted from motor vehicles, when combines with haemoglobin, decreases the oxygen carrying capacity of blood and affects the central nervous system. Other vehicular pollutants can cause allergies, respiratory diseases, nausea, eye irritation, cardiovascular diseases etc. Oxides of nitrogen can cause respiratory diseases. Cigarette smoke can cause oral and lung cancer, severe asthma, bronchitis, eyes and nose irritation etc. Smoke produced by burning wood and coal can cause tuberculosis and other respiratory diseases. Oxides of sulphur like sulphur dioxide (SO2) emitted from combustion of fossil fuels can cause cardiovascular diseases and lung disorders.
2. Water pollution can cause water-borne diseases like typhoid, jaundice, cholera, hepatitis, dysentery, malaria etc. These are communicable diseases, spread through polluted water. It is not necessary that all these diseases are spread only when consuming polluted water. Some diseases require agents for transmission. For example, a pathogen called plasmodium spread malaria with the help of mosquitoes. However, cholera, typhoid and jaundice are some diseases spread through consuming polluted water. An example of water pollution is that of a factory in Japan discharged its chemical wastes containing mercury into the Minamata Bay. People consumed shellfish and fish from the Bay and lead to accumulation of mercury in their bodies. Over 3000 victims have been recorded as having Minamata disease. Even birds and cats of the same area were affected seriously. The disease affects the central nervous system of the body.
3. Noise pollution affects both physiological and psychological health of a person. Unwanted noise can damage ears. High noise can cause temporarily or permanently hearing loss. Studies have shown that high intensity noise can cause heart related problems. Continuous exposure to noise can affect working efficiency and child’s ability to learn. Noise leads to anger and frustration, stress, distraction, sleep loss, etc.
Effects on weather and climate
The important effects of air pollution on weather and climate include global warming, ozone depletion, acid rain and smog.
Carbon-dioxide (CO2), methane (CH4), Chlorofluorocarbons (CFC's), nitrous oxide (NO2), etc are some of greenhouse gases, responsible for the global warming. Imbalance in the proportion of these gases leads to global warming. Global warming is nothing but the increase in the average temperature of atmosphere due to increase in the proportion of the greenhouse gases. It is said that Earth has warmed about 1 F in the last 100 years.
• Global warming leads to change in the climate pattern and also adversely affect crop production.
• Global warming leads to prolonged droughts, rising sea levels, hotter in summer or colder in winter, unseasonable rain and melting glaciers.
Ozone layer is made of ozone molecules which is present in the upper atmospheric region around the earth. Ozone layer absorbs Ultraviolet rays coming from sun. Thus, the layer protects all living organisms from harmful effects of Ultraviolet rays. When chlorofluorocarbons (CFC's), a green house gas, react with the ozone molecules to form carbon dioxide and thus depletion of ozone takes place. A well known example is that of Antarctica, where ozone depletion occurs each year and lasts for several weeks. Effects of ozone depletion are given below:
• When ultra-violet rays penetrate through the reduced ozone layer affect aquatic and terrestrial organisms.
• Ozone depletion can cause skin cancers. People living in regions below ozone depleted areas show skin related problems.
When oxides of nitrogen and sulphur, emitted from industries react with moisture present in air to form nitric acid and sulphuric acid respectively. These acids mix with rain water and come in the form of rain called acid rain. Acid rain affects the entire ecosystem. Following are the adverse effects of acid rain:
• Some micro-organisms increase or maintain the fertility and nutritional value of soil. Acid rain harms those micro-organisms and thus affects trees and crops.
• When acid rain mix up with the water reservoir can affect the aquatic organisms. It leads to death of fish. Consuming the water can cause asthma and bronchitis.
• Acid rain affects statues and buildings made up of limestone and marble. Acid rain is affecting India's great historic monument Taj Mahal. Walls of the monument are made up of marble. The walls are turning yellow due to react with acid rain.
Smog is the thick and smoky layer in the sky near the horizon, at the time of sunrise or sunset during the winter or cold season. Smog is nothing but the combination of smoke and fog. Smoke can contain the mixture of volatile organic compounds, nitrogen oxides, carbon monoxide and sulphur dioxide. Effects of smog are as follows:
• Smog leads to low visibility. Low visibility leads to severe accidents. It affects road, air and rail traffic. Especially, north and west regions of India are mostly affected with smog during cold season.
• Smog can cause throat, eye and nose irritation, asthma, bronchitis, chest pain, coughing, etc. In 1952, very thick smog developed in London. About 4000 people died because of severe respiratory ailments and other effects.
Effects on ecosystem
Ecosystems are affected by air, water, land and noise pollution. Small effects of pollutants can make a chain of impacts. Eutrophication and Biomagnification are very common example of pollution on ecosystem.
The process in which growth of algae or other aquatic plants takes place is called Eutrophication. It is a natural process, generally occurs in pond, lake and river. A small effect of pollution can accelerate the process of Eutrophication. Effects of Eutrophication are as follows:
• Eutrophication involves overuse of dissolved oxygen by algae or other aquatic plants like water hyacinth. Due to this, other aquatic organisms like fish present in the reservoir suffocate and die due to absence of dissolved oxygen.
• The aquatic organisms grow after the process can produce methane gas, which is a pollutant and gives a typical smell.
• Reservoirs in which the process occurs may be an invitation to mosquitoes and hence increases the risk of malaria.
• The process changes taste of water, affects transparency of water and smell of water.
Biomagnification can understand better with below example of three stages:
• Stage I: Farmers use pesticides or fungicides on the crops. Birds like sparrows feed on such crops which are sprayed with pesticides and fungicides.
• Stage II: When top predators like eagles, hawks, etc eat these sparrows undergo a part of the magnification.
• Stage III: Finally, eggs of the top predators have thinner shells that break easily.
In this way, Biomagnification forms a chain of impacts and affects all those organisms that come under the chain. The above example shows that how careless activities by human affect the other living organisms.
Control measures of pollution
The Government of India has made some laws for control and prevention of environmental pollution. The laws are as follows:
1. Air (Prevention and Control of Pollution) Act, 1981
2. Water (Prevention and Control of Pollution) Act, 1974
3. Environment (Protection) Act, 1986.
However, the government has made certain bodies that regular check whether these laws are being followed or not. They are Central Pollution Control Board (CPCB) and State Pollution Control Boards (SPCB). CPCB is a board which is regulated by the Central Government of India. On the other side, SPCB is regulated by State Government. CPCB have fully control over State boards. SPCB checks whether the laws are being followed by municipalities, grampanchayats, zilla parishads, manufacturing industries etc.
Following are the control measures of pollution:
• Planting more and more trees is a best method to control pollution. Trees maintain ecological balance of the ecosystem by producing oxygen. Trees fight against global warming. One should encourage others to grow trees.
• Urban sewage and industrial wastes and effluents should not directly discharge into water reservoirs. These should be treated first before releasing into water reservoirs. Treatment of sewage removes pollutants from the water.
• Do not throw unwanted or useless materials like plastics, papers, materials made up of iron, steel, etc. These substances can be recycled. Open burning of agricultural wastes lead to air pollution; instead it can be used as natural fertilizer.
• Ignorant farmers use artificial fertilizers and pesticides indiscriminately on the croplands and crops. Excessive use of these substances leads to land and water pollution. These should be applied on croplands and crops in recommended dose, decided by ISI (Indian Standard Institutes) experts. Government should undertake the responsibility to educating farmers so that they can use fertilizers and pesticides properly. Cow dung should not be used as a fuel. It can be used to produce Gobar gas.
• Maintain vehicles in well tuned condition and regularly serviced. A poorly maintained engine can emits more pollutants and uses more fuel. If possible, use public transport. Use bicycle in place of motorcycle.
• Industries emitting gaseous pollutants should use effective methods to control or less their effects. Bag filters, Settling chambers, Wet collectors, etc are such methods.
• Do not burn wastes. Put them in dustbins. One should use carry bags made up clothes. Avoid plastic carry bags. Avoid smoking. Keep your home and public places clean. If possible, use solar water heater and solar cooker.
• To avoid occupational noise, workers should use ear plugs. Do not play speakers in high volume. Machines of industries should be lubricated and well maintained. Industries should be placed away from residential areas. Trees near highways and streets act as a barrier to noise and thus control noise pollution.
Pollution is continuously affecting our ecosystem. It is very important to know about the ill effects of pollution. But, such knowledge will be meaningless if we fail to control pollution. So, each one of us must contribute to control the pollution both individually and through collective efforts.