The problem created by the use of plastics bags is primarily due to shortcomings in the waste management system. Indiscriminate chemical additives pose environmental problems including choking open drains, ground water contamination, etc.
Plastics are polymers i.e. large molecules consisting of repeating units called monomers. In the case of plastic bags, the repeating units are ethylene. When ethylene molecules are polymerized to form polyethylene, they form long chains of carbon atoms in which each carbon is also bonded to two hydrogen atoms.
Plastic bags are made from one of the three basic types of polymers -polyethylene- High Density polyethylene (HDPE), Low Density Polyethylene (LDPE), or Linear Low-Density Polyethylene (LLDPE). Grocery bags are generally of HDPE, and bags from the dry cleaner are LDPE. The major difference between these materials is the degree of branching of the polymer chain. HDPE and LLDPE are composed of linear, un-branched chains, while LDPE chains are branched.
Plastics are not intrinsically toxic or harmful. But plastic carry bags are manufactured using organic and inorganic additives like colourants and pigments, plasticizers, antioxidants, stabilizers and metals.
Colourants and pigments are industrial azodyes which are used to give bright colour to plastic carry bags. Some of these are carcinogenic and likely to contaminate food stuffs, if packed in these carry bags. Heavy metals such as Cadmium contained in pigments can also reach out and prove to be a health hazard.
Plasticizers are organic esters of low volatile nature. They can migrate to food stuffs as a result of leaching. Plasticizers are also carcinogenic.
Antioxidants and Stabilizers are inorganic and organic chemicals to protect against thermal decomposition during manufacturing process.
Toxic metals like cadmium and lead when used in manufacturing of plastic bags also leach out and contaminate the food stuffs. Cadmium when absorbed in the low doses can cause vomiting and heart enlargement. Lead exposure in long term may cause degeneration of brain tissues.
Plastic bags if not disposed properly may find their way into the drainage system resulting into choking of drains, creating unhygienic environment and causing water borne diseases. Recycled /coloured plastic bags may contain certain chemicals, which can leach to the ground and contaminate soil and sub-soil water. Units not equipped with environmentally sound techniques for recycling may create environmental problems due to toxic fumes generated during reprocessing. Some of the plastic bags which contain leftover food or which get mixed up with other garbage are eaten by animals resulting in harmful effects. Because of the non-biodegradable and impervious nature of plastics, if disposed in the soil, they could arrest the recharging of ground water aquifers. Further, to improve the properties of plastic products and to inhibit degradation reactions, additives and plasticisers, fillers, flame retardants and pigments are generally used, these may have health impacts.
Thin plastic bags have little value and their segregation is difficult. If the thickness of plastic bags is increased, it would make plastic bags expensive and check their usage. The plastic Manufacture Association and rag pickers could also be involved in the waste collection and disposal system.
Littering of Plastic carry bags, water bottles, plastic pouches have been a challenge for municipal solid waste management. In the country, 17 States / Union Territories have imposed complete ban on manufacture, stock, sale and use of plastic carrybags, through directions/notifications and executive orders. Further, use of plastic carry bags has been partially banned in some pilgrimage centres, tourist and historical places located in the States of Andhra Pradesh, Arunachal Pradesh, Assam, Goa, Gujarat, Karnataka, Odisha, Tamil Nadu, West Bengal, Uttar Pradesh and Uttarakhand.The Government has notified Plastic Waste Management Rules, 2016, which, inter-alia, regulate manufacture, sale, distribution and use of plastic carry bags including carry bags of compostable plastic, and plastic sheets for packaging or wrapping applications. The use of carry bags made from conventional plastic with thickness less than 50 micron is prohibited. The use of plastic for packaging gutkha, tobacco and pan masala is also prohibited.
The use of jute or cloth bag as alternatives to plastic paper bag should be popularized and prompted through fiscal incentives; however, it needs to be noted that paper bag involve cutting of trees and their use is limited. Ideally bio-degradable plastic bags alone should be used and research work is on to develop biodegradable plastics.Source: PIB
What is Ozone?
Ozone is a form of oxygen. But unlike oxygen, ozone is a poisonous gas. Each ozone molecule is made of three oxygen atoms, so its chemical formula is 03. Ozone is formed when ultraviolet radiation causes oxygen molecules (02) in the upper layers of the atmosphere to split apart. If a freed oxygen atom (O) bumps into an oxygen molecule (02), the three oxygen atoms re-form as ozone (03 ).
Good and bad ozone
In the stratosphere (the layer that is about 15 - 50 kms above the earth's surface), where ozone exists naturally, it prevents the sun's ultraviolet rays from reaching the earth and thereby protects life.
In the atmospheric layer closest to the earth's surface, due to pollution by vehicles, nitrogen oxides and Hydrocarbons levels increase. In the presence of sunlight, these chemicals form ozone. This ozone can cause health problems like coughing, throat irritation, aggravation of asthma, bronchitis etc. It can also damage crops. While ozone in the stratosphere benefits life on Earth by blocking ultraviolet radiation from the Sun, ozone in the lower atmosphere can trigger health problems.
What is ozone depletion?
Chlorofluorocarbons (CFCs) are the primary Ozone depleting chemicals. They are used as refrigerants in refrigerators, air conditioners etc. They contain Chlorine.
Ozone depletion process
How ozone depletion affects us?
When the ozone layer gets depleted, the UV radiation of the sun striking the earth gets increased. This can cause genetic damage, skin cancer (melanoma and non-melanoma), premature aging of skin, cataracts and other eye damage and can also lead to immune system suppression. It can also have adverse effects on marine environment.
Source : Treaties, United Nations Environment Programme
What is Pollution
Pollution is the release of harmful environmental contaminants, or the substances so released. Generally the process needs to result from human activity to be regarded as pollution. Any human activity is liable to be regarded as pollution, if it results in negative effects later on.
Sources of pollution
Types of pollution
Traditional forms of pollution include air pollution, water pollution, and radioactive contamination while a broader interpretation of the word has led to the ideas of ship pollution, light pollution, and noise pollution.
Noise, by definition, is unwanted sound. It is now increasingly understood that pollution from noise is an important component of air pollution.
Noise travels through air and hence it is measured in ambient air quality level. Noise is measured in decibels. Experts believe that continuous noise levels in excess of 90 decibels can cause loss of hearing and irreversible changes in nervous systems. The World Health Organization (WHO) has fixed 45 decibels as the safe noise level for a city. Metropolitan areas in India usually register an average more than 90 decibels; Mumbai is rated the third noisiest city in the world, with New Delhi following closely.
Noise not only causes irritation or annoyance but also constricts the arteries, and increases the flow of adrenaline and forces the heart to work faster. Continuous noise causes an increase in the cholesterol level resulting in permanent constriction of blood vessels, making one prone to heart attacks and strokes. Health experts are of the opinion that excessive noise can also lead to neurosis and nervous breakdown.
Waste and Water Pollution
When toxic substances enter lakes, streams, rivers, oceans, and other water bodies, they get dissolved or lie suspended in water or get deposited on the bed. This results in the pollution of water whereby the quality of the water deteriorates, affecting aquatic ecosystems. Pollutants can also seep down and affect the groundwater deposits.
The effects of water pollution are not only devastating to people but also to animals, fish, and birds. Polluted water is unsuitable for drinking, recreation, agriculture, and industry. It diminishes the aesthetic quality of lakes and rivers.
Air pollution is the contamination of air by the discharge of harmful substances. Air pollution can cause health problems and it can also damage the environment and property. It has caused thinning of the protective ozone layer of the atmosphere, which is leading to climate change.
Industries, vehicles, increase in the population, and urbanization are some of the major factors responsible for air pollution. Air pollution results from a variety of causes, not all of which are within human control. Dust storms in desert areas and smoke from forest fires and grass fires contribute to chemical and particulate pollution of the air.
Listed below are the major air pollutants and their sources.
Carbon monoxide (CO) is a colourless, odourless gas that is produced by the incomplete burning of carbon-based fuels including petrol, diesel, and wood. It is also produced from the combustion of natural and synthetic products such as cigarettes. It lowers the amount of oxygen that enters our blood . It can slow our reflexes and make us confused and sleepy.
Carbon dioxide (CO2) is the principle greenhouse gas emitted as a result of human activities such as the burning of coal, oil, and natural gases.
Chloroflorocarbons (CFC) are gases that are released mainly from air-conditioning systems and refrigeration. When released into the air, CFCs rise to the stratosphere, where they come in contact with few other gases, which leads to a reduction of the ozone layer that protects the earth from the harmful ultraviolet rays of the sun.
Lead is present in petrol, diesel, lead batteries, paints, hair dye products, etc. Lead affects children in particular. It can cause nervous system damage and digestive problems and, in some cases, cause cancer.
Ozone occur naturally in the upper layers of the atmosphere. This important gas shields the earth from the harmful ultraviolet rays of the sun. However, at the ground level, it is a pollutant with highly toxic effects. Vehicles and industries are the major source of ground-level ozone emissions. Ozone makes our eyes itch, burn, and water. It lowers our resistance to colds and pneumonia.
Nitrogen oxide (NOx) causes smog and acid rain. It is produced from burning fuels including petrol, diesel, and coal. Nitrogen oxides can make children susceptible to respiratory diseases in winters.
Suspended particulate matter (SPM) consists of solids in the air in the form of smoke, dust, and vapour that can remain suspended for extended periods and is also the main source of haze which reduces visibility. The finer of these particles, when breathed in can lodge in our lungs and cause lung damage and respiratory problems.
Sulphur dioxide (SO2) is a gas produced from burning coal, mainly in thermal power plants. Some industrial processes, such as production of paper and smelting of metals, produce sulphur dioxide. It is a major contributor to smog and acid rain. Sulfur dioxide can lead to lung diseases.
There are many different sources of chemical pollution, including:
However, the chemicals that are probably of most concern for everyone are the persistent pollutants: those substances that enter marine food chains and are eventually passed along the chain to the marine top predators in increasing amounts. Persistent pollutants include pesticides, such as DDT, and industrial chemicals, most famously the PCBs.
"Acid rain" is a broad term referring to a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. The precursors, or chemical forerunners, of acid rain formation result from both natural sources, such as volcanoes and decaying vegetation, and man-made sources, primarily emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) resulting from fossil fuel combustion. Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. The result is a mild solution of sulfuric acid and nitric acid. When sulfur dioxide and nitrogen oxides are released from power plants and other sources, prevailing winds blow these compounds across state and national borders, sometimes over hundreds of miles.
Effects of Acid Rain
Acid rain causes acidification of lakes and streams and contributes to the damage of trees at high elevations (for example, red spruce trees above 2,000 feet) and many sensitive forest soils. In addition, acid rain accelerates the decay of building materials and paints, including irreplaceable buildings, statues, and sculptures that are part of our nation's cultural heritage. Prior to falling to the earth, sulfur dioxide (SO2) and nitrogen oxide (NOx) gases and their particulate matter derivatives—sulfates and nitrates—contribute to visibility degradation and harm public health.
There are several ways to reduce acid rain—more properly called acid deposition—ranging from societal changes to individual action. It is critical that acid deposition be reduced, not only in India, but also throughout the world to preserve the integrity of natural habitats, as well as to reduce damage to man-made structures.
Last Modified : 3/2/2020
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