CC604-ENVIRONMNET AND WATER POLLUTION

DEPARTMENT : CIVIL ENGINEERING DEPARTMENT

LECTURER : PN. ZARINA SUHAILA

TOPICS : PHENOMENA OF OZONE DEPLETION

NAME : MOHAMAD SYAFIQ B. MOHAMAD HABIT (16DKA11F1081)

MUHAMMAD DANIAL B OTHMAN (16DKA11F1177)

MUHAMAD IZWANUDDIN BIN ABDULLAH (16DKA11F1157)

MUHAMMAD HANAFI BIN HASSIM (16DKA11F1083) NURUL FATTAH MAIMUNAH (16DKA11F1148) BT LOKMAN HAKIM

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CONTENT

No Title Page

1 Definition of Air Pollution 2

2 Effect of Air Pollution to Ozone 3-4

3 Where is ozone found in the atmosphere? 5-6

4 Cause of Ozone Depletion 7

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Definition of air pollution

The condition in which air is contaminated by foreign substances, or the substances themselves. Air pollution consists of gaseous, liquid, or solid substances that, when present in sufficient concentration, for a sufficient time, and under certain conditions, tend to interfere with human comfort, health or welfare, and cause environmental damage. Air pollution causes acid rain, ozone depletion, photochemical smog, and other such phenomena.

Definition of ozone layer

Belt of ozone gas 15 to 50 kilometers above the earth's surface where ozone is present in concentrations of a few parts per million.This layer blocks (absorbs) ultraviolet part of the solar radiation (which causes skin cancer) from reaching the earth's surface. Ozone depleting substances thin this layer resulting in large areas (called ozone Holes) having half or less ozone than normal to appear. In 1985, the UK researchers in Antarctica discovered thinning of ozone layer has been occurring since 1979. By 1988 it was established that the layer was thinning fast over the entire globe. Also called ozone shield.

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Effects of air pollution to ozone

A layer of ozone gas (O3) surronds the Earth about 40km above the ground. This ozone absorbs harmful UV radiation from the Sun, preventing it from reaching the ground.

Since 1976, there has been an alarming decrease in the amount of ozone in the upper layer of the atmosphere (stratosphere) over the South Pole.

What is causing the depletion of ozone in the stratosphere?

It is caused by chlorofluorocarbons (CFC). They are compounds containing the elements carbon, fluorine and chlorine.CFCs are widely used as propellants for aerosols and as coolants in refrigerators and air conditioners.

They are also used in the manufacture of packing foam.

They are very unreactive and can remain in the atmosphere for a very long time. Over years, they slowly diffuse through the air and up to the stratosphere, where they react with ozone and destroy the ozone layer.

What are the effects of ozone depletion?

The thinning of the ozone layer results in an increased exposure to UV rays from the Sun.In humans, this can cause diseases like skin cancer and cataract and may also result in a reduced resistance to diseases. Humans are also indirectly affected. Too much UV rays will damage plant tissues and destroy crops, thus reducing food production.

Other than that, Ozone in the air we breathe can harm our health—typically on hot, sunny days when ozone can reach unhealthy levels. Even relatively low levels of ozone can cause health effects.  People with lung disease, children, older adults, and people who are active outdoors may be particularly sensitive to ozone. 

Children are at greatest risk from exposure to ozone because their lungs are still developing and they are more likely to be active outdoors when ozone levels are high, which increases their exposure.  Children are also more likely than adults to have asthma.

Breathing ozone can trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. Ground level ozone also can reduce lung function and inflame the linings of the lungs. Repeated exposure may permanently scar lung tissue.

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Ozone can:

Make it more difficult to breathe deeply and vigorously. Cause shortness of breath and pain when taking a deep breath. Cause coughing and sore or scratchy throat. Inflame and damage the airways. Aggravate lung diseases such as asthma, emphysema, and chronic bronchitis. Increase the frequency of asthma attacks. Make the lungs more susceptible to infection. Continue to damage the lungs even when the symptoms have disappeared.

These effects may lead to increased school absences, medication use, visits to doctors and emergency rooms, and hospital admissions. Research also indicates that ozone exposure may increase the risk of premature death from heart or lung disease.

Ozone is particularly likely to reach unhealthy levels on hot sunny days in urban environments. It is a major part of urban smog.  Ozone can also be transported long distances by wind.  For this reason, even rural areas can experience high ozone levels

The consequences of this change are adverse as the harmful radiations reach to the surface of the earth, strongly influencing the crops yield and vegetation. These radiations are major cause of skin cancer that has long exposure to Ultra Violet (UV) radiation

Also, planktons - basic source of food for marine life - would be killed, and this will affect the entire ecosystem. Strong UV rays have also been known for deforming fish larva. In the end, all these would result in widespread hunger.

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Where is ozone found in the atmosphere?

Ozone is mainly found in two regions of the Earth's atmosphere. Most ozone (about 90%) resides in a layer that begins between 6 and 10 miles (10 and 17 kilometers) above the Earth's surface and extends up to about 30 miles (50 kilometers). This region of the atmosphere is called the stratosphere. The ozone in this region is commonly known as the ozone layer. The remaining ozone is in the lower region of the atmosphere, which is commonly called the troposphere. The figure (above) shows an example of how ozone is distributed in the atmosphere

Upper ozone layer

-The ozone molecules in the upper atmosphere is called (stratosphere). -50 kilometers (6 and 10 miles above the earth surface -Stratospheric ozone (sometimes referred to as "good ozone") plays a beneficial role by

absorbing most of the biologically damaging ultraviolet sunlight (called UV-B), allowing only a small amount to reach the Earth's surface

Lower ozone layer

-The lower atmosphere is called (troposphere). -Ozone troposphere plays a key role in the temperature structure of the Earth's

atmosphere. Without the filtering action of the ozone layer, more of the Sun's UV-B radiation would penetrate the atmosphere and would reach the Earth's surface. Many experimental studies of plants and animals and clinical studies of humans have shown the harmful effects of excessive exposure to UV-B radiation.

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Ozone layer at atmosphere

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Cause of Ozone Depletion

The ozone layer is a portion of the atmosphere that absorbs ultraviolet radiation. Ozone is the molecule responsible for this. Its structure consists of three oxygen atoms, or O3, which is one more than the normal oxygen molecule (O2) found in air. The concentration of ozone in the atmosphere is naturally low, and over time, the ozone layer has become even smaller. Several studies were conducted to find out why the ozone layer was shrinking. Most have concluded that the causes of ozone depletion should include the introduction of chemicals into the atmosphere.

Chlorofluorocarbons (CFCs)

One group of chemicals responsible for the depletion of the ozone layer is the chlorofluorocarbons. It is believed that this group of chemicals is responsible for about 80% of the damage to the ozone layer. This chemical was uses in coolants for air conditioners and refrigerators manufactured before 1995.

Hydrofluorocarbons (HCFCs)

CFCs were replaced by another group of chemicals called hydrofluorocarbons. Thee chemicals were less destructive to the ozone layer, but they still reduced the concentration of ozone in the atmosphere. HCFCs are very potent greenhouse gases.

Halons

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Another group of chemicals which affect the ozone layer is the halons. This type of chemical was commonly used in some types of fire extinguishers.

Methyl Chloroform

Methyl chloroform is another chemical that damages the ozone layer. It is commonly used for industrial applications including vapor degreasing and chemical processing.

Carbon Tetrachloride

Some types of solvents and certain compounds in fire extinguishers may contain carbon tetrachloride. This chemical negatively affects ozone.

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