Pollution

The contamination of air, water, or soil by substances that are harmful to living organisms. Pollution can occur naturally, for example through volcanic eruptions, or as the result of human activities, such as the spilling of oil or disposal of industrial waste. Light from cities and towns at night that interferes with astronomical observations is known as light pollution. It can also disturb natural rhythms of growth in plants and other organisms. Continuous noise that is loud enough to be annoying or physically harmful is known as noise pollution. Heat from hot water that is discharged from a factory into a river or lake, where it can kill or endanger aquatic life, is known as thermal pollution.


Water Pollution

Water Pollution, contamination of water by foreign matter such as micro-organisms, chemicals, industrial or other wastes, or sewage. Such matter deteriorates the quality of the water and renders it unfit for its intended uses.
Water is a major constituent of every organism and thus the most important resource to man. The pollution of water makes some rivers and lake unsafe to drink or use. Water shortage could cause devastating effects on human existance. Major water pollutants come from industries rather than domestic use. In the U.S.A water pollution has reached a higher level than any other part of the world infact not a single river in the States of America is safe to drink from!
Our life has now been simplified and as a result made it more leisure. Our improved way of living has introduce systems such as the municipal, industrial and agricultural systems. Though these systems are of advantage and therefore important to us for the continuity of healthy living they have side effects on us too.
Sewage, Infectious agents,Exotic organic chemicals such as pesticides, Inorganic minerals and chemical compounds, are all considered to be major water pollutants. Excess mineral salts from farm lands are washed away by rain water or rivers. These salts cause an artificial enrichment of salt levels in the water, this inturns provide a suitable environment for the growth of microoraganism particularly the blue algea resulting to what is know as eutrophication . These algeas flourish and cover the water surface, since they respire anaerobically they require oxygen. Their existance results to oxygen depletion in the water and a subsequent most of the aquatic plants and animals in such water die off. These dead organisms are then decomposed causing a further decrease in oxygen levels. The process of eutrophication can produce aesthetic problems such as bad tastes and odours and other chemical changes such as precipitation of calcium carbonate in hard waters. .
Sewage and other oxygen demanding wastes contribute to oxygen depletion as well.and unsightly green scums of algae, as well as dense growth of rooted plants, oxygen depletion in the deeper waters and bottom sediments of lakes, and other chemical changes such as precipitation of calcium carbonate in hard waters.
Another problem caused by water pollution, which is of growing concern in recent years, is acid rain, which has left many lakes in northern and eastern Europe and north-eastern North America totally devoid of life.
Oilspills though do not oftenly occur cause massive pollution the little while they do. Oil spills largely affect aquatic birds and since oil prevents oxygen from diffusing into the water, it also affects aquatic plants and animals.
All of the above are chemical pollutants, items such as glass and plastics bottles and bags thrown into water bodies are also considered as pollutants.
ACTION TAKEN!
Countries such as U.S.A and other developed worlds laws have been set to regulate the realise of industrial water into sewers and rivers. Proper control of water pollution has not been reached, however options are available in controlling industrial waste water. Control can take place at the point of generation within the plant; wastewater can be pretreated for discharge to municipal treatment systems; or wastewater can be treated completely at the plant and either reused or discharged directly into receiving waters.Under the current pollution law it is an offense to discharge water that has been used for any industrial purpose, into a sewer or directly into a river without the consent of the appropriate water authority. Wastes from commercial feeders are contained and disposed of on land; their main threat to natural waters, therefore, is via run-off and leaching. Control may involve settling basins for liquids, limited biological treatment in aerobic or anaerobic lagoons, and a variety of other methods. In practise this may reduce pollution but does not stop it!

Air Pollution
The presence in the atmospheric environment of natural and artificial substances that affect human health or well-being, or the well-being of any other specific organism. Pragmatically, air pollution also applies to situations where contaminants impact structures and artifacts or esthetic sensibilities (such as visibility or smell). Most artificial impurities are injected into the atmosphere at or near the Earth's surface. The lower atmosphere (troposphere) cleanses itself of some of these pollutants in a few hours or days as the larger particles settle to the surface and soluble gases and particles encounter precipitation or are removed through contact with surface objects. Unfortunately, removal of some pollutants (for example, sulfates and nitrates) by precipitation and dry deposition results in acid deposition, which may cause serious environmental damage. Also, mixing of the pollutants into the upper atmosphere may dilute the concentrations near the Earth's surface, but can cause long-term changes in the chemistry of the upper atmosphere, including the ozone layer.

Effects

The major concern with air pollution relates to its effects on humans. Since most people spend most of their time indoors, there has been increased interest in air-pollution concentrations in homes, workplaces, and shopping areas. Much of the early information on health effects came from occupational health studies completed prior to the implementation of general air-quality standards.

Air pollution principally injures the respiratory system, and health effects can be studied through three approaches, clinical, epidemiological, and toxicological. Clinical studies use human subjects in controlled laboratory conditions, epidemiological studies assess human subjects (health records) in real-world conditions, and toxicological studies are conducted on animals or simple cellular systems. Of course, epidemiological studies are the most closely related to actual conditions, but they are the most difficult to interpret because of the lack of control and the subsequent problems with statistical analysis. Another difficulty arises because of differences in response among different people. For example, elderly asthmatics are likely to be more strongly affected by sulfur dioxide than the teenage members of a hiking club. See also Epidemiology.

Damage to vegetation by air pollution is of many kinds. Sulfur dioxide may damage field crops such as alfalfa and trees such as pines, especially during the growing season (Fig. 1). Both hydrogen fluoride (HF) and nitrogen dioxide (NO2) in high concentrations have been shown to be harmful to citrus trees and ornamental plants, which are of economic, importance in central Florida. Ozone and ethylene are other contaminants that cause damage to certain kinds of vegetation.

Air pollution can affect the dynamics of the atmosphere through changes in longwave and shortwave radiation processes. Particles can absorb or reflect incoming short-wave solar radiation, keeping it from the Earth's surface during the day. Greenhouse gases can absorb long-wave radiation emitted by the Earth's surface and atmosphere.

Carbon dioxide, methane, fluorocarbons, nitrous oxides, ozone, and water vapor are important greenhouse gases. These represent a class of gases that selectively absorb long-wave radiation. This effect warms the temperature of the Earth's atmosphere and surface higher than would be found in the absence of an atmosphere (the greenhouse effect). Because the amount of greenhouse gases in the atmosphere is rising, there is a possibility that the temperature of the atmosphere will gradually rise, possibly resulting in a general warming of the global climate over a time period of several generations. See also Greenhouse effect.

Researchers are also concerned with pollution of the stratosphere (10–50 km or 6–30 mi above the Earth's surface) by aircraft and by broad surface sources. The stratosphere is important, because it contains the ozone layer, which absorbs part of the Sun's short-wave radiation and keeps it from reaching the surface. If the ozone layer is significantly depleted, an increase in skin cancer in humans is expected. Each 1% loss of ozone is estimated to increase the skin cancer rate 3–6%. See also Stratosphere.

Visibility is reduced as concentrations of aerosols or particles increase. The particles do not just affect visibility by themselves but also act as condensation nuclei for cloud or haze formation. In each of the three serious air-pollution episodes discussed above, smog (smoke and fog) were present with greatly reduced visibility.

Soil Pollution
DEFINITION:
Soil pollution is defined as the build-up in soils of persistent toxic compounds, chemicals, salts, radioactive materials, or disease causing agents, which have adverse effects on plant growth and animal health.

The wars that hit the earth are probably the immediate cause of soil pollution. Not talking in the sense of how many people died but in that it is through this period that many countries found the necessity to improve their living standards. After the world war two, many countries suffered from food shortage and this facilitated the intoruction of fertilizers and other agricultural chemicals. Although KNP [ Potassium, Nitrogen, Phosphorus] fertilisers has not led to soil pollution, the application of trace elements has.
Pesticides such as DDT [dichlorodiphenyltrichloroethane]a colourless chemical pesticide, which is a potent nerve poison in insects was first widely used to combat diseases such as yellow fever and malaria. It was later used to control and/ or eradicate disease carrying and crop eating insects. DDT was later on discovered to cause endagerement of species in the same food chain as the
controlled insects, particularly birds. DDT prevents the shelling of bird eggs and in humans causes health threats.
In yet another famous war of Vietnam in 1970's was introduced another Chemical substance which had a more adverse effect than that of DDT, Dioxin a chemical impurity resulting from the production of the auxin 2,4,5T. Dioxin is a toxic chemical and was used as a defoliant by the American army. Dioxin was a major constituent of argent orange which was applied on trees which would then fall off reaviling enemy camps. After the war it was found that the chemical cause congenital deformalities and mental effects to the children born to the American soldiers and in the area over which it was applied. In minute amount dioxin has the ability to cause cancer,chloracne, miscarriage, and fetal abnormalities.
Glass industries have also been responsible of soil pollution. The glass industries uses Arsenic to eliminate a green colour caused by impurities of iron compounds. because arsenic is a violent poison, yet it is widely used and therefore is a frequent contaminant. James Marsh, supplies a simple method for detecting traces of arsenic so minute that they would escape discovery in ordinary analysis. Arsenic is sometimes added to lead to harden it and is also used in the manufacture of such military poison gases as lewisite and adamsite. Until the introduction of penicillin, arsenic was of great importance in the treatment of syphilis. In other medicinal uses, it has been displaced by sulpha drugs or antibiotics. Lead arsenate, calcium arsenate, and Paris green are used extensively as insecticides. Pollution of land by heavy metals is a result of the mining of ores to extract metals such as tin, silver, nickel, lead, iron, chromium and copper. Most of these metals occur naturally as ions in the soils. Though some metals, such as copper, iron, and zinc , are necessary for plant growth. It is the high concentration if these ions that renders the land unsuitable for plant growth. Soil pollution is widely linked to chemical substances but irrigation. is somehow linked to it as well.
CONTROL
Soil pollution has been slightly controlled by putting regulations on the use of DDT and introduction of alternatives to it. However the task of eliminating completely soil pollution is not easy, third some third world countries still utilize pollutants such as DDT as pesticides. Mining cannot be stopped because we are in constant need for mineral ores for different applications

Noise pollution
The undesireable sound heard which irritates the human beings is sound pollution.

Hiv and Aids

Many people (not just kids, but adults, too) don't really understand how HIV and AIDS are related, even though they hear these two words used together all the time.

HIV stands for human immunodeficiency (say: ih-myoo-nuh-dih-fih-shun-see) virus. AIDS stands for acquired immunodeficiency syndrome. HIV is actually the virus that causes the disease AIDS.
HIV Hurts the Immune System

People who are HIV positive have been tested and found to have signs of the human immunodeficiency virus in their blood. HIV destroys part of the immune (say: ih-myoon) system. Specifically, it affects a type of white blood cell called the T lymphocyte (say: lim-fuh-site), or T cell. T cells are one type of "fighter" cell in the blood that help the body fight off all kinds of germs and diseases.

After HIV enters the body, it piggybacks onto a T cell and works its way inside of that cell. Once inside, the virus completely takes over the T cell and uses it as a virus-making factory to make a lot of copies of itself. The newly made viruses then leave the T cell and go on to infect and destroy other healthy T cells as they continue to multiply inside the body. After the virus invades the T cells, they can no longer properly fight infections.

Someone who is infected with the virus is called HIV positive. But it may take years for the virus to damage enough T cells for that person to get sick and develop AIDS. And thanks to new medications, someone infected with HIV can stay relatively healthy and symptom-free for many years. But these medications are very expensive and not available to everyone in the world.

Although the HIV-positive person may feel fine, the virus is silently reproducing itself and destroying T cells. And during this time, the person is still contagious (say: kon-tay-jus), which means he or she is able to give the disease to others.

When the person's immune system has weakened and more of the blood's T cells have been destroyed by the virus, the person can no longer fight off infections. This is when he or she gets very sick. A doctor diagnoses a person with AIDS when the person has a very low number of T cells and shows signs of a serious infection.
How Many People Have HIV and AIDS?

Since the discovery of the virus more than 20 years ago, millions of people throughout the world have been infected with HIV. Most are adults, but there are kids and teens who have HIV, too. In the world today, AIDS remains an epidemic (say: eh-puh-deh-mik), which means that it affects a large number of people and continues to spread rapidly.

Right now, about 40 million people in the world are living with HIV infection or AIDS. This estimate includes 37 million adults and 2.5 million children. In the United States alone, more than 1 million people are living with HIV.
How Is HIV Spread?

HIV infection isn't like a cold or the flu. A person cannot get HIV by hugging or holding the hand of, sharing a school bus or classroom with, or visiting the home of someone who has HIV. HIV is passed only through direct contact with another person's body fluids, such as blood. The majority of people in North America get infected with HIV by:

* having sexual contact with a person who has HIV
* sharing needles or syringes (used to inject illegal drugs) with a person who has HIV

Other ways of getting HIV can occur when:

* an infected pregnant woman passes it to her unborn child. (This can be prevented by treating the mother and child around the time the baby is delivered.) Because of the risk to an untreated baby, every pregnant woman should be tested for HIV.
* a person has a blood transfusion (say: trans-fyoo-zhun) from a fairly large volume of blood. But in North America today, all donated blood is tested for HIV, so the risk of getting HIV is less than one in a million.

What Are the Symptoms of HIV and AIDS?

Most people don't feel any different after they are infected with HIV. In fact, infected people often do not experience symptoms for years. Some people develop flu-like symptoms a few days to a few weeks after being infected, but these symptoms usually go away after several days.

An HIV-positive person will eventually begin to feel sick. The person might begin to have swollen lymph nodes, weight loss, fevers that come and go, infections in the mouth, diarrhea, or he or she might feel tired for no reason all of the time. Eventually, the virus can infect all of the body's organs, including the brain, making it hard for the person to think and remember things.

When a person's T cell count gets very low, the immune system is so weak that many different diseases and infections by other germs can develop. These can be life threatening. For example, people with AIDS often develop pneumonia (say: nu-mo-nyah), which causes bad coughing and breathing problems. Other infections can affect the eyes, the organs of the digestive system, the kidneys, the lungs, and the brain. Some people develop rare kinds of cancers of the skin or immune system.

Most of the children who have HIV got it because their mothers were infected and passed the virus to them before they were born. Babies born with HIV infection may not show any symptoms at first, but the progression of AIDS is often faster in babies than in adults. Doctors need to watch them closely. Kids who have HIV or AIDS learn more slowly than healthy kids and tend to start walking and talking later.
How Are HIV and AIDS Diagnosed?

A person can be infected with HIV without even knowing it. So doctors recommend that anyone who thinks he or she may have been exposed to the virus get tested - even if the chance of having been infected seems small. Doctors test a person's blood to find out if he or she is infected with HIV.

People who are HIV positive need to have more blood tests every so often. The doctor will want to check on how many T cells the person has. The lower the T cell count, the weaker the immune system and the greater the risk that someone will get very sick.
How Are HIV and AIDS Treated?

Right now there is no cure for HIV or AIDS, but new medicines can help people live longer lives. Scientists are also researching vaccines that may one day help to prevent HIV infection, but it's a very tough assignment, and no one knows when these vaccines might become available. It's up to everyone to prevent AIDS by avoiding the behaviors that lead to HIV infection.
Can HIV and AIDS Be Prevented?

People can help stop the spread of HIV by avoiding sexual contact with infected people and by not sharing needles or syringes.

Health care workers (such as doctors, nurses, and dentists) help prevent the spread of HIV by wearing plastic gloves when working on a patient. Hospitals have strict procedures for handling samples of blood and other body fluids to prevent others from coming in contact with HIV.
Living With HIV and AIDS

New drugs make it possible for people who are HIV positive to live for years without getting AIDS. They can work or go to school, make friends, hang out, and do most of the things other people can do. They will have to take certain medicines every day and see their doctors pretty often, and they may get sick more than other people do because their immune systems are more fragile.

Even though they may look OK, people who are HIV positive may sometimes feel scared, angry, unhappy, or depressed. They may feel afraid that the people at work or school could find out and start treating them differently. It is important for all of us to remember that usual social contact, like eating lunch or playing games, with people who are HIV positive does not bring any risk of infection.

When HIV infection gets worse or turns into the disease called AIDS, life really changes. The person may need to spend a lot of time in bed or in the hospital because of serious illnesses. He or she may feel very tired or weak most of the time. The person also might lose weight.
Hope for an HIV-Free Future

Maybe one day, with time and research, a cure for HIV infection will be found and AIDS will no longer exist. Until then, the smartest thing to do is to know the facts and not put yourself at risk.

Health

Health is well being psychologically,emotionally,socially and physically.If these conditions are met we can say that a person is healthy.
According to WHO " Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity."