Air pollution one of the primary causative factor of asthma, chronic obstructive disorders of lungs, lung cancer, and tuberculosis. Furthermore, air pollution can also damage the brain, kidneys, cardiac system as a result of poor oxygen levels in the air. Bad air can be destructive to crops as most of them die prematurely. Air pollution is a global issue affecting mostly the developed and developing part of the world. However, counties like India and China lead the campaign because of their enormous population that uses a lot of smoke emitting automobiles. In India, most of the metro cities like Delhi, Mumbai, Chennai, and Bangalore are in a hit list due to the poor quality air. One of the primary issues in these cities is the airborne diseases due to the substantial proportion of dust, smog, and fog in the air which is released by vehicular movements. "Air pollution is the increase in the composition of harmful chemicals including particulate matter in the air". This is even more intensive when the size of the particulate measures smaller than 2.5 um. Some of the particles causing pollution are carbon monoxide, nitric oxide, lead, arsenic, cyanide, CFC's ( Chloro Fluro carbons) and ammonia.
Causes of air pollution
The causes of air pollution can be divided into natural and man-made. Natural causes are dust, storms, forest fires and volcanoes that release a large amount of ash. Man-made causes are pollution due to excessive industrial and domestic activities, population explosion, deforestation and rapid urbanization. Specific causes of air pollution are :
1. Burning fossil fuels (coal, wood, fossils, cow dung cakes, kerosene) can form a fatal combination when combined with atmospheric air.
2. In the urban premises, the substandard engines of motor vehicles emit a lot of fumes that potentially harm the composition of atmospheric air.
3. Industries generate a greater amount of Sulfur dioxide, oxides of carbon, asbestos, nitrogen oxide, chlorine, cement, and dust as these are poisonous particulates.
4. A huge amount of Sulfur dioxide and fly-ash is released in the thermal power plants can pollute the air.
5. Fertilizers and pesticides sprays produced by agriculture can get into the inhaling air. They can seriously impact the lungs and skin.
6. Mining activities releases a lot of particulate matter into the air that can deplete the air quality.
7. Excessive cutting of trees( deforestation ) will increase the amount of carbon dioxide in the atmosphere leading to air pollution.
8. Refrigeration, fire exhausting, aerosol sprays use CFCs (chlorofluorocarbons). CFCs are potentially dangerous as they destroy the ozone layer.
Managing/controlling air pollution
The government of India has passed some legal regulations to control pollution. The 2 most important of them are the environmental protection act (1990), and environment act (1986). Each and every individual is responsible to prevent air pollution by being sensible about our activities. Although it is difficult completely to stop the effects of air pollution, some of the alternatives to help in manage the air pollution are;
1. Limiting the use of motor vehicles and replacing them with pedal cycles or vehicles with eco-friendly engines.
2. Use of hybrid cars and encouraging the use of hydrogen as a fuel in them.
3. Planting trees across roads, and vertical tree planting through skyscrapers in major towns and cities.
4. Using electrostatic precipitators, Baghouses, and Particulate scrubbers that can filter the polluted air.
5. Upgrading the industries, factories, and aircraft with quality engines.
6. Encouraging and using the renewable sources of energy like wind, water, solar, geothermal and tidal energy.
Electrostatic precipitation of air
It is one of the man-made techniques that can help to control particulates. Electrostatic precipitator is a particulate removing device help in filtering the polluted air that contains waste material including the dust, smoke, and smog. The apparatus works by forcing the polluted air to enter into an electrostatic charge. The polluted gas released from thermal plants is passed forcefully against a layer of scrubbing liquid to trap the particulate matter. The precipitator contains electrode wires emitting several thousands of volts that can release negatively charged electrons and these electrons get stick to the dust particles. As we can see in the picture below, dirty air enters into the precipitator where the electrodes become active by generating the electric current, consequently, the negatively charged wire will release electrons to bind with particulate that comes and settles on the collection plate. The collecting plates are grounded, and they attract the charged dust particles resulting in pushing the clean air once the precipitation is over. Precipitators are much effective in the removal of pollutants from the gas, but the scrubbers used in the equipment may be vulnerable to corrosion due to the constant contact with toxic gases. As per the pollution control board, the released particulate must not be smaller than 2.5 micrometers because smaller sized particulate goes deep into the lungs causing diseases.
Electrostatic precipitator( image from Britannica)
Automobile pollution and its control
India is the second-largest producer and the user of automobiles in the world. In India, 2 wheelers shares the substantial proportion of commuting vehicles, and they are the principal reason behind the emission of particulates and gases. In recent days, governments have made some regulations to adapt to catalytic converters. They are made up of platinum-palladium and rhodium that can reduce the emission. When the exhaust passes through the catalytic converter, the partly burnt hydrocarbons will be transformed into carbon dioxide and water. Similarly, carbon monoxide and nitric oxide will be changed to carbon dioxide and nitrogen gas, respectively. In addition to platinum-palladium and rhodium, the Indian government is strongly insisting on adopting compressed natural gas (CNG)to cut down the smoke emission. In the year 2002, all the buses of Delhi were converted to CNG based fuel to prevent the release of partly burnt hydrocarbons. CNG is an effective way to curb the impact of air pollution as they release minimal smoke that is completely burnt. smoke. On the other hand, CNG is much cheaper than petrol or diesel. Apart from CNG, our government has encouraged the use of unleaded petrol, low-sulfur petrol, diesel. There are also some measures where every vehicle must undergo, a regular emission testing policy. The owners of vehicles emitting solid, black emission are penalized. There is a scale that allows a maximum sulfur at 350 parts-per-million (ppm) in diesel and 150 ppm in petrol, anything excess is subjected to further action by the department of traffic control.
Check your understanding
Name any 4 reasons why air is polluted.
How can we control the excess of smoke emission in vehicles?
Explain the strategies to control the effects of air pollution.
What is the maximum sulfur emission limit in vehicular smokes?
What is electrostatic precipitation of air?