The environment is mans first right. Without a safe environment, man cannot exist to claim other rights, be they political, social, or economical.
As we know Earth is the only planet where life exists. This natural environment is getting disturbed and is out of balance over the years due to excessive pollution from various sources both natural and anthropogenic. The natural processes like volcanic activities, marsh gas production, forest fires etc. contribute to the pollution of our environment. Even without the presence of human beings, these processes occur naturally since the origin of the planet and life. But we are more concerned with anthropogenic activities, which pollute the environment. The effect of pollution depends upon human population, lifestyles (sustainable or unsustainable) and technology. Environmental pollution is defined as an undesirable change in the physical, chemical and biological characteristics of any component of the environment (water, soil, air) that can cause harmful effect on various forms of life and property. Pollution can be primary (effects immediately on release to the environment) or secondary (product of interaction after release with moisture, sunlight, other pollutants etc). Pollution may be local, regional, trans boundary or global.
Rapid industrialization has created hazards to health and the environment. As far as our country is concerned, the Indian chemical industries are the second largest in the globe. Almost all the Indian metropolitan cities are seriously polluted. More than 10,000 polluting units lie in Delhi. The Indraprastha Thermal power station emits tons of fly ash and SO2 everyday. The same is the case of the thermal power stations at Ennore and Basin Bridge, Chennai. Some of the major industries contributing to air pollution levels in Bombay are Tata thermal power plant, Bharat refineries, Hindustan petroleum etc. The importance of environmental issues is evident from the eco-watch columns of our newspapers. Also TERI, New Delhi has made digitalized electronic road displays in the capital where one could see the emission levels of important air pollutants, the humidity, temperature levels etc.
Matter can be in solid, liquid, or gaseous state and the same concept applies to air contaminants. Many metals are present in the atmosphere at trace levels. For example, particulate matter emitted from combustion of fossil fuels contains trace metals that were present in the original fuel sample. One of the greatest health hazards in air pollutants is from aerosols. Metals are emitted to the atmosphere from natural or anthropogenic sources (lead, beryllium, mercury, cadmium and chromium). Gaseous inorganic substances remain in the atmosphere for long residence times, and would continue to build up much higher levels in due course of time, if it were not for the gas phase reactions that convert these substances to water soluble species.
Sources and effects of air pollutants -
Primary and secondary pollutants
The industrial revolution around the 18th century has brought about a drastic change in the chemical composition of our atmosphere primarily due to the use of fossil fuels for energy production and transportation. Air pollution, is not a localized environmental problem but is a problem affecting the whole globe. It causes complex health problems and individual pollutant effects vary from each other. The Indian Air (Prevention and Control of Pollution) Act, 1981 defines air pollution as: Any solid, liquid or gaseous substance (including noise) present in the atmosphere in such concentrations that may or tend to be injurious to human beings or other living beings or other living creatures or plants or property or enjoyment. Air pollutants are airborne particles that occur in concentrations high enough to threaten the health of people, plants and animals, buildings and historical monuments, or that causes toxicity to a given environment. Air pollutants being in the air medium are inhaled, hence infecting the lungs and the respiratory system. Subsequently, they are taken up by blood and pumped to all parts of the body. Air pollutants can also be deposited on soil, plants, and in water because all the above mediums are interconnected and further contribute to human health risks.
Some classic case studies: Air pollution
1.Taj Mahal, Agra, India: A symbol of love affected by air pollutants
Taj Mahal means Crown Palace. Emperor Shah Jahan constructed this historic monument in the memory of his dear wife Mumtaz Mahal at Agra, India as an expression of love for his wife. It was constructed over a period of twenty-two years, employing twenty thousand workers and was completed in the year 1648. The innumerable industries in and around Agra released a large amount of sulphur dioxides, suspended particulate matter, smoke, soot etc causing tanning, blackening, and yellowing of the marble stone. The oxides reacting with rainwater resulted in acid precipitation and in return caused the deterioration and corrosion of the Taj. In 1984, Sh. M.C.Mehta, an environmental lawyer filed a public interest litigation regarding the effect of pollutants on the historic monument. Following this, the Supreme Court of India ordered 292 industries in the Taj area to be shut down and or adopt cleaner control technologies.
Most of the populated metropolitan cities like Mumbai, Chennai, Delhi, Kolkata are heavily polluted. During peak office hours the air is hazy, smoky and suffocating and is a serious problem. The Air Pollution Control Act, 1981, was passed to control and abate air pollution. Following the Bhopal gas tragedy, the Environment Protection Act, 1986 was passed. The Central Pollution Control Board passed its national ambient air quality-monitoring programme, 1985 and is being monitored by National Ambient Air Quality Monitoring Programme (NAAQM). These acts have focused on improving the quality of vehicular fuels, awareness among the general public, using renewable sources of energy and in the control of pollution.
2.The London smog of 1952: A classic air pollution case study
During the cold month of December, the people of London burnt large amounts of coal for heating their homes, which resulted in a huge amount of smoke, soot, ash, sulphur oxides etc. generated from the chimneys. On 5 December 1952, the temperature went down to -1Â°C and the humidity at 80%. There was a thick fog and the air near the ground was moist. Usually, the air close to the ground is warmer than the air above it, and therefore rises but in this particular event it resulted in the formation of a static layer of cooler air close to the ground, which is an atmospheric phenomenon called temperature inversion. The accumulation of smoke close to the ground was so much that the sunlight was totally cut off and the air stayed cool and static. The term smog means fog that has soot in it. Thousands of tons of black soot, sticky particles of tar and gaseous sulphur dioxide trapped in the fog gave it a yellow-black colour. The water from the fog condensed around the soot particles. The sulphur dioxide reacted inside the foggy, sooty droplets forming sulphuric acid producing intense acid rain. Average smoke measurements taken at the National Gallery in London between the 4 and 8 December 1952 showed that the PM concentration was 56 times the level normally experienced and the sulphur dioxide level increased by 7 times
(700 ppb). Around 4000 people died due to the smog causing pneumonia, bronchitis, tuberculosis, heart failure, asphyxiation, chest pains, inflammation of the lungs, damage to respiratory cells, permanent lung damage, respiratory ailments, susceptibility to cancers etc. The effects on vegetation were profound due to the resulting acidic rain. Following this disastrous event, London formulated the Clean Air Act, 1956 and all the traditional coal fires were converted to heaters fueled by gas, steam, hot water, oil, smokeless coal and electricity.
3.The terrible Bhopal Gas tragedy of India, 1984
Another classic case study involving air pollution is one of Worlds Worst industrial disasters, which occurred on December 3, 1984 in Bhopal, Madhya Pradesh (India). The Union Carbide Company used methyl isocyanate in manufacturing Carbaryl (carbamate) pesticides. On the fatal day none of the safety devices worked and there was a functional failure of the vent scrubber outlet. There was a violent chemical reaction in the tank and the pressure built up. This popped the safety valve open. The safety valve remained open for more than two hours releasing 50,000 lbs of gaseous and liquid MIC along with
HCN and COCl2. As a result over 30 - 40 tons of methyl isocyanate (MIC) and 35-40 kg phosgene were emitted into the atmosphere, which could be seen as thick foggy dense gas clouds. The gas spread over the entire region and city, air being the medium. Approximately 5000 people died in the disaster. More than 2,50,000 people were exposed to the gas. MIC afflicts the lungs, eyes, skin, respiratory system, gastrointestinal system etc. Also, it causes reproductive, teratogenic and mutagenic effects. The clean up of the tragedy costed approximately 570 million U.S. dollars compared to the cost of the safety devices, which would have costed only 1 million U.S. dollars if it had been installed before the tragedy. The after effects of the Bhopal gas tragedy are seen even today with people and children having genetic disorders.
Sources of air pollution
Automobile exhausts, industries, growing population, modernization, are a few major factors responsible for air pollution. They consist of inorganic, organic, gaseous pollutants, SPM (suspended particulate matter) such as dust, fumes, mist, and smoke. Anthropogenic air pollution sources are industries, energy generation, power plants, transportation etc. Since these pollutants are generally concentrated in and around urban areas, the outdoor urban pollution levels are higher than that in the rural areas lacking these industries. Fires-including forest fires, oil well fires, burning of leaves, large-scale burning of agricultural waste- are another major source of air pollution and can lead to severe problems if the smoke is inhaled for a period of time.The two important types of air pollutants based on the sources are: stationary and mobile sources. The stationary sources as the name indicates, are stationary which includes pollution from point sources (specific point, i.e. chimneys, power plants), area sources (specific area, i.e. an industrialized area) and fugitive sources (open areas exposed to wind). The mobile sources as the name indicates are mobile which includes emissions from aircrafts, ships, automobile emissions etc.