World is facing severe problem of environmental degradation due to rapid increase in population and economic development that weakens the environmental resource.
Environment pollution is worldwide issue and it has adverse impact on the health of human populations (Fereidoun et al, 2007). Universal environmental pollution, including greenhouse gas emissions and acid deposition, as well as water pollution and waste management is deliberated as global public health problems, which should be examined from manifold perspectives such as social, economic, legislation, and environmental engineering systems, as well as lifestyle habits helping health promotion and reinforcing environmental systems to repel adulteration (Loux, 2011). It is observed that the problems of environmental pollution is intense in the developing world, where traditional sources of pollution such as industrial emissions, poor sanitation, insufficient waste management, polluted water supplies and exposures to indoor air pollution from biomass fuels affect humans (Samet, 2001). Recently, modern pollutants have emerged which are associated with traffic congestion and the use of modern chemicals in the home, in food, for water treatment and for pest control.
Air Pollution has emerged as growing global issue among environmentalists and researchers especially in developed countries since the decade of 1960 (Kan, 2009). It affects human and animal lives, natural ecosystems and the man-made environment. The main pollutants found in the air people breathe include, particulate matter, PAHs, lead, ground-level ozone, heavy metals, sulphur dioxide, benzene, carbon monoxide and nitrogen dioxide (European Public Health Alliance, 2009). Air pollution in urban areas has numerous health impact such as a shorter lifespan for city inhabitants (Progressive Insurance, 2005).
Air pollution is also responsible for climate change due to the enhanced greenhouse effect, acid rain, and the depletion of the ozone layer that constitute important global environmental problems. Mishra stated that fast growth in urban population, increasing industrialization, and rising demands for energy and motor vehicles are the deteriorating air pollution levels (2003). He further said that other factors, such as poor environmental ruling, less efficient technology of production, jammed roads, and age and poor maintenance of automobiles also increase pollution level. It is established that air pollution is caused of ill health and death by natural and man-made sources. Major man-made sources of ambient air pollution include tobacco smoke, combustion of solid fuels for cooking, heating, home cleaning agents, insecticides industries, automobiles, power generation, poor environmental regulation, less efficient technology of production, congested roads, and age and poor maintenance of cars and other automobiles. The natural sources include furnaces and waste disposals, forest and agricultural fires (European Public Health Alliance, 2009). Air pollution occurs both outdoors and indoors and is caused by human activities and natural mechanisms. Outdoor air pollution is described as the discharge of numerous air pollutants in to the atmosphere, in concentrations that threaten the health of living organisms or upset the function of the environment as a system leading to human health damages in various ways. Indoor air pollution is defined as the amount of chemical, biological and physical contaminants in the air inside a building. Indoor air pollution is more dangerous as compared to outdoor air pollution. Some of indoor air pollutant sources in houses including building materials, pressed wood products and furniture, central heating and cooling systems, several personal care or household cleaning products, painting colours, solvents, heating or cooking appliances (stoves, wood and gas burning fireplaces, gas heaters), tobacco smoke, office machines and other products used in daily activities (EPA, 2007).
Consequences of Air Pollution:
Air pollution cause many health issues. It is found that CO2 is a good transmitter of sunlight, but it also partially restricts infrared radiation going back from the earth into space, which produces the greenhouse effect that prevents a drastic cooling of the Earth during the night. Increasing the amount of CO2 in the atmosphere strengthens this effect and is expected to result in a warming of the Earth's surface.
Air pollution has harmful impact on plant life. Sulphur di oxide is considered as most harmful pollutant (Rao, 1989).
Effect of pollutant on plants (Source: Rao, 1989)

Air pollution monitoring is very necessary to control pollution. These techniques collect data by scientists to enable them to make informed decisions to manage overall quality of environment.
Air pollution monitoring and source categorization (Source: Bhola, et, al., 2010)
Water pollution: Water pollution is also a matter of concern for human life. Polluted water comprises of Industrial discharged wastes, sewage water, rain water pollution (Ashraf et al, 2010). Water can also be polluted by agriculture or households cause damage to human health or the environment. (European Public Health Alliance, 2009). This water pollution adversely impacts the health and quality of soils and vegetation (Carter, 1985). Pollutants in water include a wide range of chemicals, pathogens, and physical chemistry or sensory changes. Many of the chemical substances are toxic or even carcinogenic. Pathogens can obviously produce waterborne diseases in either human or animal hosts. The effects of water pollution are major cause of death for humans at global scale. Furthermore, water pollution affects oceans, lakes, rivers, and drinking water (Scipeeps, 2009). A drinking water contained a fluoride content ranging from 5.26 to 26.32 milligrams per litre and this is too high as compared to the World Health Organization�s standard of 0.6 to 1.7 milligram per litre (Rizvi, 2000). It has been found that Paper and pulp mills consume large amount of water and discharge liquid and solid waste products into the environment. The liquid waste is usually high in biological oxygen demand, suspended solids, and chlorinated organic compounds such as dioxins (World Bank, 1999).
Types of water pollution:

Treatment of water pollution: There are many ways by which water pollution can be treated such as industrial treatment, denitrification, septic tank, and ozone waste water treatment. Before raw sewage can be carefully released back into the environment, it must be treated properly in a water treatment plant. In a water treatment plant, sewage goes through a number of chambers and chemical processes to reduce the amount and toxicity of the waste. Denitrification is an ecological approach to avert the leaching of nitrates in soil, and stops ground water pollution with nutrients. Septic tanks treat sewage at the place where it is located and used to treat sewage from an individual building. Untreated sewage from a property flows into the septic tank and the solids are separated from the liquid. Environmentalists use Biological processes to degrade the solid matter. Another method to treat water pollution is well known Ozone wastewater treatment. An ozone generator break down pollutants in the water source. The generators convert oxygen into ozone using Ultraviolet radiation and Electric discharge field. There are numerous advantages of ozone to treat wastewater such as this technique kills bacteria successfully, oxidizes substances such as iron and sulphur. There are some drawbacks of adopting ozone to treat wastewater such as it requires energy in the form of electricity, cost money and cannot work when the power is lost and cannot remove dissolved minerals and salts.
Water pollution treatment
Land/ Solid waste Pollution: This type of pollution also shake environment. Inadequate management of solid waste is one of the main causes of environmental pollution (Kimani, 2007). Land pollution is one of the main forms of environmental calamity in current situation (Khan, 2004). Causes of Land Pollution include Mining and quarrying, Sewage waste, Household Garbage and Industrial Waste. Consequences of Land Pollutants are dangerous such as extermination of wild life. In land pollution, acid rain kills trees and other plants and vegetation that provides food and shelter is destroyed. It can seriously disturb the balance of nature, and, in extreme cases, can cause human mortalities. Pesticides can damage crops; kill vegetation and poison birds, animals, and fish. Most pesticides kill or damage life forms other than those intended. To prevent Land Pollution, it is advised that more and more land should be brought under farming. Trees should be planted everywhere. Waste matter should be disposed immediately and avoid drilling the Land for more underground water. People must avoid using more chemical fertilizers and Pesticides.
Noise pollution, soil pollution and light pollution also harm the environment at an alarming rate. Causes of Noise Pollution include aircraft noise, noise of cars, buses, and trucks, vehicle horns, loudspeakers, and industry noise, as well as high-intensity sonar effects which are extremely harmful for the environment, noise from construction and civil engineering works. Extreme noise pollution occurs due to technical advancement and the motor vehicle, which is responsible for about ninety percent of all undesirable noise internationally. Effects of Noise Pollution are Hearing Loss, High Blood Pressure, Stress, Sleep Disturbance, Colour Blindness. To Avoid Noise Pollution, the Government should ensure the new machines that should be noise proof. Air ports must be away from residential area. Do not sound horn symbol is to be in school roads. Soil pollution is described as the impurity of soil of a particular region. Soil pollution mainly is a result of penetration of damaging pesticides and insecticides, which deteriorate the soil quality, thus making it contaminated and unfit for use later. Main causes of soil pollution include Industrial wastes such as harmful gases and chemicals, agricultural pesticides, fertilizers and insecticides, ignorance towards soil management and related systems, unfavourable and harmful irrigation practices, improper septic system and management and maintenance of the same, leakages from sanitary sewage, acid rains, when fumes released from industries get mixed with rains, fuel leakages from automobiles, that get washed away due to rain and seep into the nearby soil, improper waste management techniques, which are characterized by release of sewage into the large dumping grounds and nearby streams or rivers.
Light pollution is described as excessive and incorrect artificial light (Mizon, 2002). It is caused due to extreme use of artificial lights by humans. The powerful artificial light which are used to brightens offices, factories, sports stadium, street, parks and sometime even housing complexes obscure the night sky.
The four components of light pollution are often combined and may intersect:
Plethora of environmental studies have shown that environmental pollutants have various adversarial health effects. The most important harmful effects are prenatal disorders, infant mortality, respiratory disorders, allergy, malignancies, cardiovascular disorders, and increase in stress oxidative, endothelial dysfunction, mental disorders, and various other harmful effects. Though, short-term effects of environmental pollutants are usually underlined, wide range of hazards of air pollution from early life and their possible implication on chronic non-communicable diseases of adulthood should be underscored. Many studies have demonstrated that environmental particulate exposure has been linked to increased risk of morbidity and mortality from many diseases, organ disturbances, cancers, and other chronic diseases (Kargarfard, 2011). Consequently, experts advised to take immediate action and control the pollution. Otherwise, the waste products from consumption, heating, agriculture, mining, manufacturing, transportation, and other human activities will damage the environment.
Causes of deforestation: There are several causes of current deforestation such as dishonesty of government institutions, the unfair distribution of wealth and power, population growth and overpopulation, and urbanization. Globalization is also major cause of deforestation, though there are cases in which the impacts of globalization have supported localized forest recuperate.
Causes of desertification: Desertification occurs due to numerous factors, primarily anthropogenic causes, which began in the Holocene era and continues today. The primary reasons for desertification are overgrazing, over-cultivation, increased fire frequency, water impoundment, deforestation, over drafting of groundwater, increased soil salinity, and global climate change.
Multilevel set of causes of Desertification (Source: Camilla Toulmin, 1993)
Impact of environmental degradation (Source: Chalecki, 2003)
To summarize, Pollution is due to harmful substances or products into the environment. There are several types of pollutions in the environment such as Water Pollution, Air Pollution, Soil Pollution, land pollution. Environmental degradation is the collapse of the earth or worsening of the environment through consumption of assets such as air, water and soil, the destruction of environments and the annihilation of wildlife.