WHAT YOU HAVE TO KNOW ABOUT...''POLLUTION AND CONTROL''

Pollution is the introduction of contaminants into the natural environment that cause adverse change.[1] 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 non point source pollution.

1 Ancient cultures
Air pollution has always accompanied civilizations. Pollution started from prehistoric times when man created the first fires. According to a 1983 article in the journal Science, "soot found on ceilings of prehistoric caves provides ample evidence of the high levels of pollution that was associated with inadequate ventilation of open fires.” Metal forging appears to be a key turning point in the creation of significant air pollution levels outside the home. Core samples of glaciersin Greenland indicate increases in pollution associated with Greek, Roman and Chinese metal production, but at that time the pollution was comparatively small and could be handled by nature.


2 Forms of pollution

• Air pollution:
 the release of chemicals and particulates into the atmosphere. Common gaseous pollutants include carbon monoxide, sulfur dioxide, chlorofluorocarbons (CFCs) and nitrogen ox- ides produced by industry and motor vehicles. Photochemical ozone and smog are created as nitrogen oxides and hydrocarbons react to sunlight. Particulate matter, or fine dust is characterized by their micro metre size PM10 to PM₂.₅.
• Light pollution:
 includes light trespass, over- illumination and astronomical interference.
 • Littering:
 the criminal throwing of inappropriate man-made objects, unremoved, onto public and private properties.
• Noise pollution:
which encompasses roadway noise, aircraft noise, industrial noise as well as high- intensity sonar.
• Soil contamination
 occurs when chemicals are released by spill or underground leakage. Among the most significant soil contaminants are hydrocarbons, heavy metals, herbicides, pesticides and chlorinated hydrocarbons.
 • Radioactive contamination,
 resulting from 20th century activities in atomic physics, such as nuclear power generation and nuclear weapons research, manufacture and deployment. (See alpha emitters and actinides in the environment.)
 • Thermal pollution,
 is a temperature change in natural water bodies caused by human influence, such as use of water as coolant in a power plant.
 • Visual pollution, 
which can refer to the presence of overhead power lines, motorway billboards, scarred landforms (as from strip mining), open storage of trash, municipal solid waste or space debris.
 • Water pollution,
 by the discharge of waste water from commercial and industrial waste (intentionally or through spills) into surface waters; discharges of untreated domestic sewage, and chemical contaminants, such as chlorine, from treated sewage; re- lease of waste and contaminants into surface run off flowing to surface waters (including urban run off and agricultural run off, which may contain chemical fertilizers and pesticides); waste disposal and leaching into groundwater; eutrophication and littering.
 • Plastic pollution:
 involves the accumulation of plastic products in the environment that adversely affects wildlife, wildlife habitat, or humans.

3 Pollutants
A pollutant is a waste material that pollutes air, water or soil. Three factors determine the severity of a pollutant: its chemical nature,the concentration and the persistence.

4 Sources and causes
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.


5 Effects
5.1 Human health
Adverse air quality can kill many organisms including
humans. Ozone pollution can cause respiratory disease, cardiovascular disease, throat inflammation, chest pain, and congestion. Water pollution causes approximately 14,000 deaths per day, mostly due to contamination of drinking water by untreated sewage in developing countries. The WHO estimated in 2007 that air pollution causes half a million deaths per year in India. oily exposed to diseases induced by air pollution. Those with heart or lung disorders are at additional risk. Children and infants are also at serious risk. Lead and other heavy metals have been shown to cause neurological problems. Chemical and radioactive substances can cause cancer and as well as birth defects.


5.2 Environment
Pollution has been found to be present widely in the environment. There are a number of effects of this:
• Biomagnification describes situations where toxins (suchasheavymetals)maypassthroughtrophiclev- els, becoming exponentially more concentrated in the process.
 • Carbon dioxide emissions cause ocean acidification, the on going decrease in the pH of the Earth’soceans as CO2 becomes dissolved.
 • The emission of greenhouse gases leads to global warming which affects ecosystems in many ways. • Invasive species can out compete native species and reduce biodiversity. Invasive plants can contribute debris and biomolecules (allelopathy) that can alter soil and chemical compositions of an environment, often reducing native species competitiveness.
 • Nitrogenoxides are removed from the air by rainand fertilise land which can change the species compo- sition of ecosystems.
 • Smog and haze can reduce the amount of sunlight received by plants to carry out photosynthesis and leads to the production of tropospheric ozone which damages plants.
 • Soil can become infertile and unsuitable for plants. This will affect other organisms in the food web. • Sulfur dioxide and nitrogen oxides can cause acid rain which lowers the pH value of soil.

6  Pollution control
Pollution control is a term used in environmental management. It means the control of emissions and effluents into air, water or soil. Without pollution control, the waste products from consumption, heating, agriculture, mining, manufacturing,transportation and other human activities, whether they accumulate or disperse, will degrade the environment. In the hierarchy of controls, pollution prevention and waste minimization are more desirable than pollution control. In the field of land development, low impact development is a similar technique for the prevention of urban runoff.

6.1 Practices
 • recycling • reusing • Waste minimisation • mitigating • preventing • compost

6.2 Pollution control devices
• Dust collection systems • Baghouses • Cyclones • Electrostatic precipitators • Scrubbers • Baffle spray scrubber • Cyclonic spray scrubber • Ejector venturi scrubber • Mechanically aided scrubber • Spray tower • Wet scrubber • Sewage treatment • Sedimentation (Primary treatment) • Activated sludge biotreaters (Secondary treat- ment; also used for industrial wastewater) • Aerated lagoons • Constructed wetlands (also used for urban runoff) • Industrial wastewater treatment • API oil-water separators[25][48] • Biofilters • Dissolved air flotation (DAF) • Powdered activated carbon treatment • Ultrafiltration • Vapor recovery systems • Phytoremediation