Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants. Pollution is often classed as point source or nonpoint source pollution. In 2015, pollution killed 9 million people in the world. Major forms of pollution include Air pollution, light pollution, littering, noise pollution, plastic pollution, soil contamination, radioactive contamination, thermal pollution, visual pollution, water pollution. An environmental hazard is a substance, a state, or an event that has the potential to threaten the surrounding natural environment / or adversely affect people's health, including n]] and natural disasters such as storms and earthquakes. Any single or combination of toxic chemical, biological, or physical agents in the environment, resulting from human activities or natural processes, that may impact the health of exposed subjects, including pollutants such as heavy metals, pesticides, biological contaminants, toxic waste, industrial and home chemicals. Human-made hazards while not immediately health-threatening may turn out detrimental to man's well-being eventually, because deterioration in the environment can produce secondary, unwanted negative effects on the human ecosphere. The effects of water pollution may not be immediately visible because of a sewage system that helps drain off toxic substances. If those substances turn out to be persistent (e.g. persistent organic pollutants), however, they will literally be fed back to their producers via the food chain: plankton -> edible fish -> humans. In that respect, a considerable number of environmental hazards listed below are man-made (anthropogenic) hazards. Hazards can be categorized in four types: 1. Chemical 2. Physical (mechanical, etc.) 3. Biological 4. Psychosocial Hazards

1. 1
ENVIRONMENTAL HAZARD
BY
CHANDAN GUPTA

2. 2
Radioactive Pollution
Radiations are classified into two types, they are:
 Non-ionizing radiations
 Ionizing radiations
1. Non-ionizing radiations: Electromagnetic waves of a longer wavelength which are near
ultraviolet rays to radio waves areknown as non-ionizing radiations. These radiationshave
enough amount of energy to excite molecules and atoms of the medium via which they
travel. They make atoms to vibrate faster and but does not have enough amount of energy
to ionize them.
2. Ionizing radiations: These radiations are electromagnetic radiations that have high
energy like gamma rays, x-rays, and short wavelength ultraviolet radiations. These rays of
energy like alpha, beta, and gamma are generated in radioactive decay have the ability to
ionize molecules and atoms via which they travel. They also have ability to change
molecules and atoms into charged ions. Radioactive decay is a process from which alpha,
beta, and gamma radiations are generated.
Radioactive pollution and sources of radioactive pollution:
Living organisms are exposed to distinct types of radiations without a break and these radiations
are known as background radiations. Harmful effects can be caused by living organisms if
radioactive radiations enhance above a particular limit. These harmful and hazardous radiations
which are released by radioactive elements are known as radioactive pollution. Below diagram
explains about sources of radioactive pollution.
Fig1: Sources Radioactive Pollution

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1. Natural sources of radiation: Natural sources of radiation are mentioned below:
 In natural sources of radioactive pollution, atomic radioactive minerals are one among
them.
 Cosmic rays possess high energy ionizing electromagnetic radiation.
 Another sourceofradioactive radiation is naturally occurringradioisotopes.Radioisotopes
are found in soil in small quantity.
 Radioactive elements like radium, thorium, uranium, isotopes of potassium and carbon
occur in lithosphere.
2. Anthropogenic sources of radiation: Human activities mentioned below include in
sources of radioactive pollution:
 Nuclear tests
 Nuclear reactors
 Diagnostic medical applications
 Nuclear Wastes
 Nuclear explosions
 Nuclear metal processing
Effects of ionizing radiation:
If a humanbodyis exposedto any type ofradiation like alphaparticles, betaparticles, gamma rays,
and x-rays then it can lethal and harmful. Biological effects of radiation on human type are of two
types and those are:
 Genetic
 Non-genetic or body damage
1. Genetic damage: Chromosomes and genes get altered in genetic damage. In this damage,
effects can be seen in offsprings as deformations. Breaks in genetic material i.e. DNA, a
molecule having genetic data is known as mutation.
2. Non-genetic damage: In non-genetic damage, the effect gets visible immediately in form
of burns, birth defects, and a type of leukemia, tumors, miscarriages, fertility difficulties,
and cancer of one or more organs.

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Type of radiation Effect on body
Alpha particles An alpha particle cannot enter the skin but if
their sources are present inside the body
then they can damage lungs and bones.
Beta particles Beta particles can go inside the skin but
cannot damage tissues. They have the ability
to damage to eyes and skin.
X-rays X-rays have ability to pass through tissues
and travel far. They cannot travel through
bones. They can damage cells.
Gamma radiation They have an ability to easily enter the body
and pass through it. Cell structure can get
damage because of them.
Table1: effects of radioactive radiation on living organisms
Effects of radiation and doses of radiation:
Biological damage which happens because of radiation depends on below-mentioned factors:
 Whether radiation is arising from outside the human or from inside human body
 Type of penetration power i.e. ionizing radiation
 Intensity of radiation
 Time of exposure

5. 5
Thermal Pollution
Major effects of thermal pollution
Few major effects of thermal pollution are explained below:
 Contamination of water
 Depleted level of oxygen in natural water
 Thermal shock which results in increase in temperature in water bodies
 Decreased solubility of oxygen
 Adverse effect on water plants
 Adverse effect on water animals
 Unexpected migration of water animals
 Unfavorable effect on water biodiversity
 Effect on population of water animals
 Disturbance in biological activities of water animals
Causes of pollution
Below diagram explains the important causes of thermal pollution and those are:
Fig1: Chief Causes of Thermal Pollution

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Management of Thermal Pollution
 Theoretically speaking, an engine once works at one hundred percent capability it releases
heat at its full level and it’s cooled by water that eventually returns into water bodies
inflicting pollution. Therefore, we have a tendency to can’t recommend operation of
Associate in Nursing engine below its full capability and however through maximizing the
potency of warmth engine this menace of pollution is reduced slighter and this can be its
solely answer.
 Moreover, for the effective management of pollution by a thermal method, whereas
manufacturing power mechanical friction in rotating components ought to be reduced,
energy ought to be consumed to a minimum level and use of civil atomic energy ought to
be promoted because it releases less dioxide.
Sources of Thermal Pollution
The various causes of pollution are as follows:
 Coal-fired Power Plants: Few thermal power plants avail coal as fuel. Power plants which
use coal represent the key supply of the pollution.
 Industrial Effluents: Industries producing electricity require a great deal of cooling water
for warmth removal. Alternative industries like textile, pulp, paper, and sugar business
conjointly release heat in water, however to a lesser extent.
 Atomic power Plants: Nuclear power plants release an oversized quantity of unused heat
and traces of virulent radio nuclear into close water streams.
 Domestic Sewage:Domestic sewerageis commonlydischargedinto rivers,canals, andlakes
without waste treatment. The municipal water sewerage ordinarily contains a higher tem-
perature than receiving water. With the rise in temperature of the receiving water the
dissolved atomic number 8 content (DO) decreases and therefore the demand of oxygen
will increase and anaerobic conditions occur.
Controlling Thermal Pollution
Control of pollution is important as its prejudicious effects on an aquatic system could also be
prejudiciouswithin the future. Viablesolutions to chronic thermal discharge into water bodiesare
explained below:
 Cooling Ponds: Cooling ponds or reservoirs represent the best technique of dominant
thermal discharges. This is often the best and most cost-effective technique which helps in
losing the heat ofthe water to a substantial low temperature. However,the technique alone
is a smaller amount fascinating and inefficient in terms which tell about air-water contact.
 Cooling Towers: Availing water sources of water for cooling functions, with consequent
come back to the water body once going through the condenser is called as the cooling
method. So as to form the cooling method more practical, cooling towers are made to
regulate the temperature of water. Well, cooling towers are availed to dissipate the
recovered waste heat thus on eliminate the issues of pollution.
 Artificial Lake: These lakes are artificial bodies of water which supply attainable various to
once through cooling. The warmth is eventually dissipated through vaporization. These
artificial lakes have to be compelled to be rejuvenated ceaselessly. A variety of ways is
prompt and developed for changing the liquid waste discharged from power plants into
helpful heat resources for maximizing the advantages.

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Along with this, below are the preventive measures to control thermal pollution:
 Using less electricity
 Using better-applied sciences
 Holding back the water for good
 Planting more trees on banks of water bodies
 Spreading awareness among people
 Recycling used water
 Cogeneration
 Suitable arrangements in urban areas
Below diagram explains about cumulative emission of carbon dioxide by distinct countries from
1750 – 2006:
Fig2: Cumulative Carbon Dioxide Emission

8. 8
Noise Pollution
The sound is mechanical energy from a vibrating source. The unpleasant and unwanted sound is called
as noise.
Sources of noise pollution: The main sources of noise pollution are various modes of
transportation, industrial operations, construction activities and celebrations, electric home
appliances.
Causes of noise pollution: It exists mostly in densely populated areas like cities and industrial
complexes, railway stations, bus stations, air ports, television, radio, and even kitchen gadgets generate
noise. Sound levels are measured in units called decibels. Conservation produces sound at about 40
decibels and so on. The limit that humans can accept is about 110 decibels without pain and damage.
Effect of noise: Noise causes the following effects:
 Interferes with man’s communication
 Healing damage
 Physiological and psychological changes
Control of noise pollution: The noise pollution can be controlled by the following:
 Reduction in sources of noise
 Proper oiling will reduce the noise from the machinery
 Planting more tree which has broad leaves
The figure is the diagrammatic representation of the effects of noise pollution:
Fig2: effects of noise pollution