This document provides information on various types of environmental pollution including water pollution, air pollution, soil pollution, noise pollution, and others. It discusses causes and sources of different types of pollution as well as control measures that can be implemented. Some key points include: - Water, air, soil, and land can all become polluted from various natural and human-made sources. Control measures aim to prevent discharge of pollutants and set standards to protect health and environments. - Sources of air pollution include vehicle emissions, industrial activities, agriculture, and more. Prevention methods control gaseous and particulate pollutants through combustion, absorption, adsorption, and other technologies. - Soil pollution can be reduced

1. EDUCATION HOLE PRESENTS
ENGINEERING CHEMISTRY
Unit-III

2. Environmental Pollution.......................................................................................................... 3
Causes of pollution...........................................................................................................................3
Control measures for water pollution...............................................................................................4
Water quality use designations ............................................................................................................................4
Recreational activities include..............................................................................................................................5
Aquatic life habitats..............................................................................................................................................5
Water pollution control criteria............................................................................................................................5
Control measures for thermal pollution ...........................................................................................6
Air pollution ............................................................................................................................ 6
Sources of Air Pollution.........................................................................................................................................7
Prevention And Control of Air Pollution ...............................................................................................................7
Soil Pollution ........................................................................................................................... 8
Control of Marine pollution..............................................................................................................9
Land pollution ....................................................................................................................... 11
Causes of Land Pollution ................................................................................................................ 11
Solutions for Land Pollution................................................................................................................................12
Noise pollution ...................................................................................................................... 12
Climate change .............................................................................................................................. 12
Greenhouse effect.......................................................................................................................... 13
Global warming..................................................................................................................... 13
Acid rain......................................................................................................................................... 14
The Effects of Acid Rain ......................................................................................................................................14
Ozone layer formation........................................................................................................................................15
Ozone layer depletion.........................................................................................................................................15
Impact of water and air borne diseases on human health .............................................................. 16
Waterborne diseases..........................................................................................................................................16
Air borne diseases.......................................................................................................................... 16
Toxic wastes................................................................................................................................... 17
Carcinogens ................................................................................................................................... 17
Nuclear hazards ............................................................................................................................. 18
Natural Radiation................................................................................................................................................18
Man-Made Radiation..........................................................................................................................................18

3. Environmental Pollution
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.
Although environmental pollution can be caused by natural events such as forest fires and active
volcanoes, use of the word pollution generally implies that the contaminants have an
anthropogenic source that is, a source created by human activities. Pollution has accompanied
humankind ever since groups of people first congregated and remained for a long time in any one
place. Indeed, ancient human settlements are frequently recognized by their pollutants shell
mounds and rubble heaps, for instance. Pollution was not a serious problem as long as there was
enough space available for each individual or group. However, with the establishment of
permanent settlements by great numbers of people, pollution became a problem, and it has
remained one ever since.
Causes of pollution
Air pollution comes from both natural and human-made (anthropogenic) sources. However,
globally human-made pollutants from combustion, construction, mining, agriculture and warfare
are increasingly significant in the air pollution equation. Motor vehicle emissions are one of the
leading causes of air pollution. China, United States, Russia, India Mexico, and Japan are the
world leaders in air pollution emissions. Principal stationary pollution sources include chemical
plants, coal-fired power plants, oil refineries, petrochemical plants, nuclear waste disposal
activity, incinerators, large livestock farms (dairy cows, pigs, poultry, etc.), PVC factories,
metals production factories, plastics factories, and other heavy industry. Agricultural air
pollution comes from contemporary practices which include clear felling and burning of natural
vegetation as well as spraying of pesticides and herbicides.
About 400 million metric tons of hazardous wastes are generated each year. The United States
alone produces about 250 million metric tons. Americans constitute less than 5% of the world's
population, but produce roughly 25% of the world’s CO2, and generate approximately 30% of
world’s waste. In 2007, China has overtaken the United States as the world's biggest producer of
CO2, while still far behind based on per capita pollution - ranked 78th among the world's nations.
In February 2007, a report by the Intergovernmental Panel on Climate Change (IPCC),
representing the work of 2,500 scientists, economists, and policymakers from more than 120

4. countries, said that humans have been the primary cause of global warming since 1950. Humans
have ways to cut greenhouse gas emissions and avoid the consequences of global warming, a
major climate report concluded. But to change the climate, the transition from fossil fuels like
coal and oil needs to occur within decades, according to the final report this year from the UN's
Intergovernmental Panel on Climate Change (IPCC). Some of the more common soil
contaminants are chlorinated hydrocarbons (CFH), heavy metals (such as chromium, cadmium–
found in rechargeable batteries, and lead–found in lead paint, aviation fuel and still in some
countries, gasoline), MTBE, zinc, arsenic and benzene. In 2001 a series of press reports
culminating in a book called Fateful Harvest unveiled a widespread practice of recycling
industrial byproducts into fertilizer, resulting in the contamination of the soil with various
metals. Ordinary municipal landfills are the source of many chemical substances entering the soil
environment (and often groundwater), emanating from the wide variety of refuse accepted,
especially substances illegally discarded there, or from pre-1970 landfills that may have been
subject to little control in the U.S. or EU. There have also been some unusual releases of
polychlorinated dibenzodioxins, commonly called dioxins for simplicity, such as TCDD.
Control measures for water pollution
Water pollution refers to the qualitative state of impurity or uncleanliness in hydrologic waters of
a certain region, such as a watershed. It results from an occurrence or process which causes a
reduction in the utility of the earth’s waters, especially as related to human health and
environmental effects. The pollution process stresses the loss of purity through contamination,
which further implies intrusion by or contact with an outside source as the cause. The term
tainted is applied to extremely low levels of water pollution, as in their initial corruption and
decay. Defilement is the result of pollution and suggests violation or desecration.
Water quality use designations
The ultimate goal in the control of water pollution would be zero discharge of pollutants to water
bodies; however, complete achievement of this objective is usually not cost effective. The
preferred approach is to set limitations on waste disposal discharges for the reasonable protection
of human health and the environment. Although these standards may vary widely in different
jurisdictions, use designations for specific bodies of water are commonly the basis, as briefly
addressed below.
Water supplies include:
• public water supply: waters which with conventional treatment will be suitable for human
consumption
• agricultural supply: waters suitable for irrigation and livestock watering without
treatment

5. • Industrial/commercial supply: waters suitable for industrial and commercial uses with or
without treatment.
Recreational activities include
• bathing waters: waters which during certain seasons are suitable for swimming as
approved for water quality along with protective conditions and facilities
• primary contact: waters which during certain seasons are suitable for full body contact
recreation such as swimming, canoeing and underwater diving with minimal threat to
public health as a result of water quality
• secondary contact: waters which during certain seasons are suitable for partial body
contact recreation such as, but not limited to, wading, with minimal threat to public
health as a result of water quality.
Public water resources are categorized as water bodies which lie within park systems, wetland,
wildlife areas, wild, scenic and recreational rivers and publicly owned lakes, and waters of
exceptional recreational or ecological significance.
Aquatic life habitats
Typical designations will vary according to climates, but relate to conditions in water bodies for
supporting and maintaining certain aquatic organisms, especially various species of fish. For
example, use designations in a temperate climate as subdivided in regulations for the State of
Ohio Environmental Protection Agency (EPA) are listed below without detailed descriptions:
• warmwater
• limited warmwater
• exceptional warmwater
• modified warmwater
• seasonal salmonid
• coldwater
• limited resource water.
Water pollution control criteria
Natural waters and wastewaters are characterized in terms of their physical, chemical and
biological composition. The principal physical properties and the chemical and biological
constituents of wastewater and their sources are a lengthy list, reported in a textbook by Metcalf
and Eddy (1991). Analytical methods for these determinations are given in a widely used manual
entitled Standard Methods for the Examination of Water and Waste Water by the American
Public Health Association (1995).

6. Control measures for thermal pollution
The following methods can be adapted to control high temperature caused by thermal discharges:
1. Cooling towers: Use of water from water systems for cooling systems for cooling
purposes, with subsequent return to the water way after passage through a condenser, is
called cooling process. Cooling towers transfer heat from hot water to the atmosphere by
evaporation. Cooling towers are of two types:
(i) Wet cooling tower: Hot water coming out from the condenser (reactor) is allowed to
spray over baffles. Cool air, with high velocity, is passed from sides, which takes away
the heat and cools the water.
(ii) Dry cooling tower: Here, hot water is allowed to flow in long spiral pipes. Cool air
with the help of a fan is passed over these hot pipes, which cools down hot water. This
cool water can be recycled.
2. Cooling ponds: Cooling ponds are the best way to cool thermal discharges. Heated
effluents on the surface of the water in cooling ponds maximise dissipation of heat to the
atmosphere and minimise the water area and volume. The warm water wedhe acts like a
cooling pond.
3. Spray ponds: The water coming out from condensers is allowed to pass into the ponds
through sprayers. Here water is sprayed through nozzles as fine droplets. Heat from the
fine droplets gets dissipated to the atmosphere.
4. Artificial lakes: Artificial lakes are man made water bodies that offer once-through
cooling. The heated effluents can be discharged into the lake at one end and water for
cooling purposes may be withdrawn from the other end. The heat is eventually dissipated
through evaporation.
Air pollution
Air pollution is the introduction of chemicals, particulates, biological materials, or other harmful
materials into the Earth's atmosphere, possibly causing disease, death to humans, damage to
other living organisms such as food crops, or the natural or built environment. The atmosphere is
a complex natural gaseous system that is essential to support life on planet Earth. Stratospheric
ozone depletion due to air pollution has long been recognized as a threat to human health as well
as to the Earth's ecosystems. Indoor air pollution (see Airlog) and urban air quality are listed as
two of the world’s worst toxic pollution problems in the 2008 Blacksmith Institute World's
Worst Polluted Places report.

7. Sources of Air Pollution
The pollution of air can be caused by natural processes or by human activities. The sources of air
pollution are classified into two groups:
1. Natural Sources
2. Man made sources
Natural Sources of Air Pollution: They are dust storms, forest fires, ash from smoking volcanoes,
decay of organic matters and pollen grains floating in air.
Manmade Sources of Air Pollution: They are population explosion, deforestation, urbanization
and industrialization, whose effects can be explained as follows:
1. Burning of fuels like wood, cow dung cakes, coal and kerosene in homes pollute the air.
2. Exhaust gases emitted by motor vehicles which pollute the air are the major source of air
pollution in big cities.
3. Industries pollute air by releasing various types of pollutants such as sulphur dioxide,
oxides of carbon, nitrogen oxide, chlorine, asbestos dust and cement dust.
4. Thermal power plants pollute air by emitting sulphur dioxide and fly-ash.
5. Nuclear power plants pollute air by releasing radioactive rays.
6. Use of fertilisers and pesticides in agriculture pollute the air.
7. Mining activities releases particulate matter into the air and pollutes it.
8. Indiscriminate cutting of trees and clearing of forests increases the amount of carbon
dioxide in the atmosphere and thereby pollutes it.
9. Use of chlorofluorocarbons in refrigeration, fire extinguishers and aerosol sprayers
pollutes air by depleting the ozone layer.
10. Smoking pollutes air by emitting carbon monoxide and nicotine.
Prevention And Control of Air Pollution
Different techniques are used for controlling air pollution caused by 'gaseous pollutants' and that
caused by 'particulate pollutants'.
• Methods of controlling gaseous pollutants: The air pollution caused by gaseous pollutants
like hydrocarbons, sulphurdioxide, ammonia, carbon monoxide, etc can be controlled by
using three different methods-Combustion, Absorption and Adsorption.
1. Combustion: This technique is applied when the pollutants are organic gases or vapours.
The organic air pollutants are subjected to 'flame combustion or catalytic combustion'

8. when they are converted to less harmful product carbon dioxide and a harmless product
water.
2. Absorption: In this method, the polluted air containing gaseous pollutants is passed
through a scrubber containing a suitable liquid absorbent. The liquid absorbs the harmful
gaseous pollutants present in air.
3. Adsorption: In this method, the polluted air is passed through porous solid adsorbents
kept in suitable containers. The gaseous pollutants are adsorbed at the surface of the
porous solid and clean air passes through.
• Methods of controlling particulate emissions: The air pollution caused by particulate
matter like dust, soot, ash, etc, can be controlled by using fabric filters, wet scrubbers,
electrostatic precipitators and certain mechanical devices.
1. Mechanical Devices: It works on the basis of following:
• Gravity: In this process, the particulate settle down by the action of gravitational force
and get removed.
• Sudden change in the direction of air flow: It brings about separation of particles due to
greater momentum.
2. Fabric Filters: The particulate matter is passed through a porous medium made of woven or
filled fabrics.
• The particulate present in the polluted air are filtered and gets collected in the fabric
filters , while the gases are discharged.
• The process of controlling air pollution by using fabric filters is called 'bag filtration'.
3. Wet Scrubbers: They are used to trap SO2, NH3 and metal fumes by passing the fumes
through water.
4. Electrostatic Precipitators: When the polluted air containing particulate pollutants is passed
through an electrostatic precipitator, it induces electric charge on the particles and then the
aerosol particles get precipitated on the electrodes.
Soil Pollution
The following measures may be suggested to control soil pollution:
1. Development of such pesticides should be encouraged, which may save crops from pests and
rodents but should not contaminate soil with toxic chemicals.

9. 2. Pesticides and fertilizers should be applied on croplands only in recommended dose,
prescribed by Indian Standard Institution experts. It will help in reducing the level of water and
soil pollution caused through these chemicals.
3. There should be sufficient duration between the harvesting of crops and time of last spray of
pesticides. This will help in reducing contamination of pesticides, directly to the crop. It will also
cause less contamination of chloride and other chemicals to the soil.
4. There must be arrangement for educating farmers regarding the proper use of pesticides and
fertilizers. Only those fertilizers could be used for growing crops, which are deficient in soils.
5. After every two or three years soils percentage should be analyzed, so that it can be observed
that what is the percentage of nutrients in the soils. This will help in maintaining the required
amount of nutrient in the soils.
6. Waste water from industries should not be used for irrigation without eliminating toxic
chemicals from the effluent. This will also reduce the concentration of unwanted substances in
the soil.
7. Garbage should not be disposed of on cultivated land without covering it with the soils.
8. Soil conservation practices should also be adopted so as to avoid loss of valuable nutrients
through soil erosion.
In addition to this, government should encourage research programmers examining the effects of
pesticides and fertilizers on soils and human beings. This will help in devising suitable measures
to control soil pollution and restore its fertility.
Control of Marine pollution
Oil spills are harmful to aquatic plants and animals, including fish, birds and people. Oil will
affect the roads and drinking water. Gasoline and oil contain carcinogenic substances known to
cause cancer. Marine oil pollution are man-made threats to the lakes and streams as quickly as
possible. These are issued to small recreational vessels leak larger, heavier oil in commercial
vessels. Manage these potentially dangerous leaks, it is essential to the waterways as quickly as
possible.
Prevention of oil pollution control, bilge-water disposal, fuel and oil spill cleanup, the Federal
Water Pollution Control Act of 1972 and the Oil Pollution Act 1990 prohibits any discharge of
oil at or near the navigable waters of the United States. This includes the discharge of the film,
sheen, discoloration, sludge or emulsion caused at or below the water surface. The discharge of
these species could lead to stiff civil penalties.

10. A quarter of the oil creates a ripple effect that is larger than 2 acres in diameter. One liter of fuel
pollute a million gallons of water. Gasoline and other petroleum negative impact on the marine
environment and should be included.
To prevent pollution of the sea, absorbent bilge pads to receive petroleum products, but no water.
When the bilge water is
Bilge Booms
- Reduces the tree with not saturated with oil they should be removed. If not properly disposed of
the main sources of marine pollution
they collect oil, antifreeze and transmission fluids.
If the bilge pump is activated, the liquid is pumped into the water.
Solution: a bilge bilge, the oil tank or sump fluctuations.
- Replace oil absorbent inserts under the engine
- Replace oil absorbent materials contaminated with highly saturated
- Keep your engine tuned: Check for leaking seals, gaskets and hoses.
- Change oil filters are often
- Do not allow oily bilge pump or displayed in or near water
Bilge sink rails not yet saturated. Bilge arms can float indefinitely. Bilge rails can be kept to the
public, free of dust and impervious to both rot and mildew. They come with loops a rope for easy
installation and confirm. Bilge rails is available in three sizes.
Problem: Motor Boat of the Oil Spill
Fuel is spilled while the gas engine. Sometimes there is a backsplash out of fuel, or a vent valve
in the overflow. Harmful to aquatic organisms such spills. If a leak is not a snake in the water.
Much better use of oil absorbent sweep to clear the spillage
Solution: oil-absorbing Sweep
If the use of fuel oil spilled into the water-absorbing Sweep. Oil
Absorbent Sweep purpose built hinges. A large absorbent surface made of a large spills, absorb
or surface sheen. This is a great way to clean oil spills in the water. Never use soap or detergent
oil distribution. The cleaners will bring roads and non-biodegradable. Detergents is a major
source of pollution.
Solution 2: Oil Absorbent Booms
Oil absorbent booms and perfect offshore oil industry based on strong mesh screens Bund
Encasing the outer skin, a highly sorbent polypropylene filler. A nylon rope and steel hardware
ensure long life and easy retrieval. Water repellent and oil-absorbent Booms are not yet saturated

11. sink. Oil absorbent arms are 5 “and 8″ in diameter with a length of 10 Ft or 20 Ft Cleaning up the
oil can be achieved by using sorbents, gels and foams.
Land pollution
When we talk about air or water pollution, the reactions garnered are stronger. This is because
we can see the effects caused by the pollutants and their extent very clearly. It is normal human
psychology to believe in what you see first hand. Our land on the other hand is living a
nightmare too. We may not be able to see the effects with clarity, but land is being polluted and
abused constantly and we are unable to calculate the damages incurred. Land Pollution has come
to become one of the serious concerns that we collectively battle.
Causes of Land Pollution
1. Deforestation and soil erosion: Deforestation carried out to create dry lands is one of the major
concerns. Land that is once converted into a dry or barren land, can never be made fertile again,
whatever the magnitude of measures to redeem it are. Land conversion, meaning the alteration
or modification of the original properties of the land to make it use-worthy for a specific purpose
is another major cause. This hampers the land immensely. Also there is a constant waste of land.
Unused available land over the years turns barren; this land then cannot be used. So in search of
more land, potent land is hunted and its indigenous state is compromised with.
2. Agricultural activities: With growing human population, demand for food has increased
considerably. Farmers often use highly toxic fertilizers and pesticides to get rid off insects, fungi
and bacteria from their crops. However with the overuse of these chemicals, they result in
contamination and poisoning of soil.
3. Mining activities: During extraction and mining activities, several land spaces are created
beneath the surface. We constant hear about land caving in; this is nothing but nature’s way of
filling the spaces left out after mining or extraction activity.
4. Overcrowded landfills: Each household produces tonnes of garbage each year. Garbage like
aluminum, plastic, paper, cloth, wood is collected and sent to the local recycling unit. Items that
can not be recycled become a part of the landfills that hampers the beauty of the city and cause
land pollution.
5. Industrialization: Due to increase in demand for food, shelter and house, more goods are
produced. This resulted in creation of more waste that needs to be disposed of. To meet the
demand of the growing population, more industries were developed which led to deforestation.
Research and development paved the way for modern fertilizers and chemicals that were highly
toxic and led to soil contamination.

12. Solutions for Land Pollution
o Make people aware about the concept of Reduce, Recycle and Reuse.
o Reduce the use of pesticides and fertilizers in agricultural activities.
o Avoid buying packages items as they will lead to garbage and end up in landfill
site.
o Ensure that you do not litter on the ground and do proper disposal of garbage.
o Buy biodegradable products.
o Do Organic gardening and eat organic food that will be grown without the use of
pesticides.
o Create dumping ground away from residential areas.
Noise pollution
Follow the below given steps for controlling and preventing noise pollution.
• Control of Noise pollution at Source
• Noise producing industries, railway stations, aerodrome, etc. should be located far away
from the residential areas.
• We should play various music systems such as stereos, television, etc. at low volume.
• We should not use loud speakers during night. Even during time they should be used at
low volumes.
• Various machines should be well maintained so that they produce less sound.
• It is observed that certain persons blow horns of their vehicles unnecessarily, or remove
silencers of the exhaust pipes of vehicles. Such practices produce lot of noise and should
be avoided.
• Laws should be framed so that the persons producing unnecessary noise are punished.
Control of Noise Pollution by obstructing the path of Noise
• By constructing soundproof buildings, the menace of sound pollution can be minimized.
• Plants also help in controlling noise pollution because they absorb high frequency sound
waves. Thus, planting trees along the roads help in controlling noise pollution.
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather
patterns over periods ranging from decades to millions of years. It may be a change in average
weather conditions, or in the distribution of weather around the average conditions (i.e., more or

13. fewer extreme weather events). Climate change is caused by factors such as biotic processes,
variations in solar radiation received by Earth, plate tectonics, and volcanic eruptions. Certain
human activities have also been identified as significant causes of recent climate change, often
referred to as "global warming".
Scientists actively work to understand past and future climate by using observations and
theoretical models. A climate record extending deep into the Earth's past has been assembled,
and continues to be built up, based on geological evidence from borehole temperature profiles,
cores removed from deep accumulations of ice, floral and faunal records, glacial and periglacial
processes, stable-isotope and other analyses of sediment layers, and records of past sea levels.
More recent data are provided by the instrumental record. General circulation models, based on
the physical sciences, are often used in theoretical approaches to match past climate data, make
future projections, and link causes and effects in climate change.
Greenhouse effect
Greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed
by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-
radiation is back towards the surface and the lower atmosphere, it results in an elevation of the
average surface temperature above what it would be in the absence of the gases. Solar radiation
at the frequencies of visible light largely passes through the atmosphere to warm the planetary
surface, which then emits this energy at the lower frequencies of infrared thermal radiation.
Infrared radiation is absorbed by greenhouse gases, which in turn re-radiate much of the energy
to the surface and lower atmosphere. The mechanism is named after the effect of solar radiation
passing through glass and warming a greenhouse, but the way it retains heat is fundamentally
different as a greenhouse works by reducing airflow, isolating the warm air inside the structure
so that heat is not lost by convection. If an ideal thermally conductive blackbody was the same
distance from the Sun as the Earth is, it would have a temperature of about 5.3 °C. However,
since the Earth reflects about 30% of the incoming sunlight, this idealized planet's effective
temperature (the temperature of a blackbody that would emit the same amount of radiation)
would be about −18 °C. The surface temperature of this hypothetical planet is 33 °C below
Earth's actual surface temperature of approximately 14 °C. The mechanism that produces this
difference between the actual surface temperature and the effective temperature is due to the
atmosphere and is known as the greenhouse effect
Global warming
Since the dawn of the Industrial Revolution in the early 1800s, the burning of fossil fuels like
coal, oil and gasoline have greatly increased the concentration of greenhouse gases in the

14. atmosphere, especially CO2, according to NASA. CO2 and other greenhouse gases act like a
blanket, absorbing IR radiation and preventing it from escaping into outer space. The net effect is
the gradual heating of Earth's atmosphere and surface, a process known as global warming.
Atmospheric CO2 levels have increased by more than 40 percent since the beginning of the
Industrial Revolution, from about 280 parts per million (ppm) in the 1800s to 400 ppm today.
The last time Earth's atmospheric levels of CO2 reached 400 ppm was during the Pliocene
Epoch, between 5 million and 3 million years ago, according to the University of California, San
Diego's Scripps Institution of Oceanography.
Acid rain
Acid rain is a result of air pollution. When any type of fuel is burnt, lots of different chemicals
are produced. The smoke that comes from a fire or the fumes that come out of a car exhaust don't
just contain the sooty grey particles that you can see - they also contains lots of invisible gases
that can be even more harmful to our environment. Power stations, factories and cars all burn
fuels and therefore they all produce polluting gases. Some of these gases (especially nitrogen
oxides and sulphur dioxide) react with the tiny droplets of water in clouds to form sulphuric and
nitric acids. The rain from these clouds then falls as very weak acid - which is why it is known as
"acid rain". Acidity is measured using a scale called the pH scale. This scale goes from 0 to 14. 0
is the most acidic and 14 is the most alkaline (opposite of acidic). Something with a pH value of
7, we call neutral, this means that it is neither acidic nor alkaline. Very strong acids will burn if
they touch your skin and can even destroy metals. Acid rain is much, much weaker than this,
never acidic enough to burn your skin. Rain is always slightly acidic because it mixes with
naturally occurring oxides in the air. Unpolluted rain would have a pH value of between 5 and 6.
When the air becomes more polluted with nitrogen oxides and sulphur dioxide the acidity can
increase to a pH value of 4. Some rain has even been recorded as being pH2.
The Effects of Acid Rain
Acid rain can be carried great distances in the atmosphere, not just between countries but also
from continent to continent. The acid can also take the form of snow, mists and dry dusts. The
rain sometimes falls many miles from the source of pollution but wherever it falls it can have a
serious effect on soil, trees, buildings and water. Forests all over the world are dying, fish are
dying. In Scandinavia there are dead lakes, which are crystal clear and contain no living
creatures or plant life. Many of Britain's freshwater fish are threatened, there have been reports
of deformed fish being hatched. This leads to fish-eating birds and animals being affected also. Is
acid rain responsible for all this? Scientists have been doing a lot of research into how acid rain
affects the environment.

15. Ozone layer formation
Over two billion years ago, early aquatic organisms called blue-green algae began using energy
from the Sun to convert molecules of water (H2O) and carbon dioxide (CO2) and recombine
them into organic compounds and molecular oxygen (O2). This solar energy conversion process
is known as photosynthesis. Some of the photosynthetically created oxygen began to accumulate
in the atmosphere, touching off a massive ecological disaster with respect to early existing
anaerobic organisms. As oxygen in the atmosphere increased, CO2 decreased. High in the
atmosphere, some oxygen (O2) molecules absorbed energy from the Sun's ultraviolet (UV) rays
and split to form single oxygen atoms. These atoms combined with molecular oxygen (O2) to
form ozone (O3) molecules, which are very effective at absorbing UV rays. The thin layer of
ozone that surrounds Earth acts as a shield, protecting the planet from irradiation by UV light.
The amount of ozone required to shield Earth from biologically lethal UV radiation, wavelengths
from 200 to 300 nanometers (nm), is believed to have been in existence 600 million years ago.
At this time, the oxygen level was approximately 10% of its present atmospheric concentration.
Prior to this period, life was restricted to the ocean. The presence of ozone enabled organisms to
develop and live on the land.
Ozone layer depletion
The ozone layer is a belt of naturally occurring ozone gas that sits 9.3 to 18.6 miles (15 to 30
kilometers) above Earth and serves as a shield from the harmful ultraviolet B radiation emitted
by the sun. Ozone is a highly reactive molecule that contains three oxygen atoms. It is constantly
being formed and broken down in the high atmosphere, 6.2 to 31 miles (10 to 50 kilometers)
above Earth, in the region called the stratosphere. Today, there is widespread concern that the
ozone layer is deteriorating due to the release of pollution containing the chemicals chlorine and
bromine. Such deterioration allows large amounts of ultraviolet B rays to reach Earth, which can
cause skin cancer and cataracts in humans and harm animals as well. Extra ultraviolet B radiation
reaching Earth also inhibits the reproductive cycle of phytoplankton, single-celled organisms
such as algae that make up the bottom rung of the food chain. Biologists fear that reductions in
phytoplankton populations will in turn lower the populations of other animals. Researchers also
have documented changes in the reproductive rates of young fish, shrimp, and crabs as well as
frogs and salamanders exposed to excess ultraviolet B. Chlorofluorocarbons (CFCs), chemicals
found mainly in spray aerosols heavily used by industrialized nations for much of the past 50
years, are the primary culprits in ozone layer breakdown. When CFCs reach the upper
atmosphere, they are exposed to ultraviolet rays, which causes them to break down into
substances that include chlorine. The chlorine reacts with the oxygen atoms in ozone and rips
apart the ozone molecule.

16. Impact of water and air borne diseases on human health
Waterborne diseases
• Droughts can cause increased concentrations of effluent pathogens, overwhelming water
treatment plants and contaminating surface water. Older water treatment plants are
particularly at risk.
• Changes in ocean and coastal ecosystems, including changes in pH, nutrient and
contaminant runoff, salinity, and water security, that can cause degradation of fresh
water, particularly in areas where much of the population uses untreated surface water for
daily consumption and activities.
• Increased frequency of intense extreme weather events can cause flooding of water and
sewage treatment facilities, increasing the risk of waterborne diseases.
• Indirectly, the lack of water can cause pressure on agricultural productivity, crop failure,
malnutrition, starvation, population displacement, and resource conflict.
• Changes can occur in the distribution and concentrations of chemical contaminants in
coastal and ocean waters through the release of contaminants previously locked in polar
ice she
Air borne diseases
Climatic factors such as absolute humidity have been associated with risk of lower respiratory
tract infection. Respiratory syncytial virus (RSV) is one of the most important viral respiratory
pathogens especially for infants. The epidemic activity of RSV infection is related to
meteorological conditions and thus to latitude: persistently high temperature and humidity results
in epidemic peaks in summer and early autumn, while in temperate climates RSV infection peaks
in the winter. A causal link with temperature seems inconsistent based on these climatic data, but
the RSV infection season in England and Wales has ended earlier and its duration has shortened
as the climate has become warmer. Seasonality has been documented for a number of other
respiratory infections including tuberculosis, and seasonal fluctuations of El Niño-southern
oscillation in California are associated with the impact of influenza epidemics (hospital
admissions or mortality profiles;) but a direct link to climate change has not been established.
Furthermore, increased use of cooling towers during heat waves might increase the risk for
exposure to Legionella spp, although appropriate public health measures should be able to
contain this risk.
On the basis of the articles reviewed here, it is not possible to draw conclusive
inferences about the link between airborne diseases and climate change, but it might shorten the
transmission season.

17. Toxic wastes
Toxic waste is waste material that can cause death, injury or birth defects to living creatures. It
spreads quite easily and can contaminate lakes, rivers, and the atmosphere. The term is often
used interchangeably with “hazardous waste”, or discarded material that can pose a long-term
risk to health or environment. Hazardous wastes are poisonous byproducts of manufacturing,
farming, city septic systems, construction, automotive garages, laboratories, hospitals and other
industries. The waste may be liquid, solid, or sludge and contain chemicals, heavy metals,
radiation, dangerous pathogens, or other toxins. Even households generate hazardous waste from
items such as batteries, used computer equipment, and leftover paints or pesticides. In the United
States, the Environmental Protection Agency (EPA) and the state departments oversee the rules
that regulate hazardous waste. The EPA requires that toxic waste be handled with special
precautions and be disposed of in designated facilities around the country. Also, many cities in
the United States have collection days where household toxic waste is gathered. Some materials
that may not be accepted at regular landfills are ammunition, commercially generated waste,
explosives/shock sensitive items, hypodermic needles/syringes, medical waste, radioactive
materials, and smoke detectors.
Carcinogens
A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in
causing cancer. This may be due to the ability to damage the genome or to the disruption of
cellular metabolic processes. Several radioactive substances are considered carcinogens, but their
carcinogenic activity is attributed to the radiation, for example gamma rays and alpha particles,
which they emit. Common examples of non-radioactive carcinogens are inhaled asbestos, certain
dioxins, and tobacco smoke. Although the public generally associates carcinogenicity with
synthetic chemicals, it is equally likely to arise in both natural and synthetic substances.
Carcinogens are not necessarily immediately toxic, thus their effect can be insidious. Cancer is
any disease in which normal cells are damaged and do not undergo programmed cell death as
fast as they divide via mitosis. Carcinogens may increase the risk of cancer by altering cellular
metabolism or damaging DNA directly in cells, which interferes with biological processes, and
induces the uncontrolled, malignant division, ultimately leading to the formation of tumors.
Usually, severe DNA damage leads to apoptosis, but if the programmed cell death pathway is
damaged, then the cell cannot prevent itself from becoming a cancer cell

18. Nuclear hazards
The world's nuclear fleet creates about 10,000 metric tons of high-level spent nuclear fuel each
year. High-level radioactive waste management concerns management and disposal of highly
radioactive materials created during production of nuclear power. The technical issues in
accomplishing this are daunting, due to the extremely long periods radioactive wastes remain
deadly to living organisms. Of particular concern are two long-lived fission products,
Technetium-99 (half-life 220,000 years) and Iodine-129 (half-life 15.7 million years), which
dominate spent nuclear fuel radioactivity after a few thousand years. The most troublesome
transuranic elements in spent fuel are Neptunium-237 (half-life two million years) and
Plutonium-239 (half-life 24,000 years). Consequently, high-level radioactive waste requires
sophisticated treatment and management to successfully isolate it from the biosphere. This
usually necessitates treatment, followed by a long-term management strategy involving
permanent storage, disposal or transformation of the waste into a non-toxic form.
Governments around the world are considering a range of waste management and disposal
options, usually involving deep-geologic placement, although there has been limited progress
toward implementing long-term waste management solutions. This is partly because the
timeframes in question when dealing with radioactive waste range from 10,000 to millions of
years, according to studies based on the effect of estimated radiation doses.
Natural Radiation
Natural radiation is a by-product of processes and materials created when the earth was formed.
The sun on which we all depend for heat and light produces very highly charged particles called
cosmic rays. We are exposed continuously to this radiation every day. Not many people realize
that we all have radiation sources within our bodies, usually in the form of potassium.
Radioactive potassium occurs naturally in the earth and is therefore present in trace amounts in
the food we eat and the water we drink. Additionally, radioactivity from uranium and thorium is
found in rocks and soil. For example, radon gas is a source of radiation that results from the
decay of uranium found in the earth. Radon gas has recently been identified as a concern because
it can penetrate through the foundation of homes. Recent studies show that radon gas contributes
more than half of our radiation exposure each year.
Man-Made Radiation
Our environment contains many sources of radiation. Some of these sources are natural in origin,
either originating from the sun or from radioactive materials that have resided in the earth since
its formation. Other sources are man-made. X-ray machines are used for dental and medical
purposes, television sets are used for entertainment and microwave ovens are used to cook foods.

19. Nuclear power plants use the energy of radiation to convert water to steam, which is then used to
generate electricity.