Friday, 5 May 2017

An Overview on Air Pollution and its Effects on Humanity

Air is one of the most important constituents of man’s environment. An average human being requires about 12kg of air each day, which is nearly 12 to 15 times greater than the amount of food consumed. Air pollution can be defined as the presence in the outdoor or indoor   atmosphere of one or more gaseous or particulate   contaminants in quantities, characteristics and of   duration such as to be injurious to human, plant or  animal life or to property, or which unreasonably  interferes with the comfortable enjoyment of life and  property). The World Health Organization (WHO) defines air pollution as limited to situations in which the outer ambient atmosphere contains materials in concentrations   which are harmful to man and his environment.

A substance in the air that can   cause harm to humans and the environment is known as an air pollutant and air  pollutants are expressed as a ppm or ug/m3 which is subjected to change to variations  of temperature and pressure. These pollutants   can either be primary or secondary pollutants. Primary pollutants remain in the same form as when they are  released from a source directly into the atmosphere like sulphur dioxide while secondary pollutants occur  as a result of chemical reaction between two or more pollutants.  

Sources of air pollution refer to the various locations, activities or factors which are responsible for the releasing of pollutants into the atmosphere. These sources can be  classified into two major categories which are: Anthropogenic sources (human activity), which include pipeline explosion, gas flaring, chemical fertilizer industry, industrial emission, refuse burning etc. and Natural sources which includes  Methane, emitted by the digestion of food by  animals - for example cattle,  radon gas from radioactive decay within the  Earth's crust, from natural smoke and carbon monoxide from wildfires, vegetation in some regions emits environmentally  significant amounts of volatile organic compunds on warmer days  and volcanic activity which produce sulphur, chlorine and ash particulates.

Air pollution is a problem that is directly related to the number of people living in
an area and the kinds of activities they engaged in. In a place where the population is low and their energy usage is also low, the impact of people in creating pollution is minimal. However where the population is high, the area urbanized and industrialized with high energy usage large quantities of pollutants are released into the environment. It is clearly obvious that the greater the concentration of people in one area, the greater the amount of pollution and the greater the sophistication of a society the more intricate and poignant its pollution.

The World Health Organization states that 2.4  million people die each year from causes directly  attributable to air pollution, with 1.5 million of these  deaths attributable to indoor air pollution. The health effects caused by air pollution may include difficulty in breathing, wheezing, coughing and aggravation of existing respiratory and cardiac conditions. Individual reactions to air pollutants depend on the type of pollutant a person is exposed to, the degree of exposure, the individual's health status and genetics.

Air pollution control is more effective when point source dispersion modeling is applied in its analysis.  This includes; Line Source Dispersion; used for airport  and roadway air dispersion modeling, Area Source Dispersion; used for forest fires or dust storms and Photo-chemical models. Air pollution can also be prevented through:

• Carpool: This will help to reduce the number of vehicles on the already congested roads.
• Energy saving: Use of minimum amount of natural gas and even electricity. Whenever  possible, avoid the use of air conditioner and use a  fan instead.
• Always buy recycled products.
• Reuse things such as paper and plastic bags, paper etc. This will contribute a lot towards reducing the effects of air pollution and global warming.
• Avoid the use of firecrackers.
• Go in for water-based paints instead of varnishes.

The following items are commonly used as pollution control devices by industry or transportation devices. They can either destroy contaminants or remove them from an exhaust stream before it is emitted into the atmosphere.

Particulate control:
• Mechanical collectors (dust cyclones, multicyclones)
• Electrostatic precipitators.
• Bag houses designed to handle heavy dust loads, a dust collector consists of a blower, dust filter, a filter-cleaning system and a dust receptacle or dust removal system (distinguished from air cleaners which utilize disposable filters to remove the dust).

• Particulate scrubbers.
Scrubbers: Baffle spray scrubber, Cyclonic spray scrubber, Ejector venturi scrubber, mechanically aided scrubber, Spray tower, Wet scrubber
NOx control: Low NOx burners, Selective Catalytic Reduction (SCR), Selective Non-Catalytic, Reduction (SNCR) NOx scrubbers, Exhaust gas recirculation, Catalytic converter (also for VOC control).
VOC abatement: Adsorption systems, such as   activated carbon, Flares, Thermal oxidizers, Catalytic converters, Biofilters, Absorption (scrubbing), Cryogenic condensers, Vapor recovery systems
Acid Gas / SO2 control: Wet scrubbers, Dry scrubbers, Flue gas desulfurization
Mercury control: Sorbent Injection Technology, Electro-Catalytic Oxidation (ECO), K-Fuel Dioxin and Furan control

In conclusion, we as citizens all have a part to play in attaining a sustainable environment that is pollution free. We have to admit that every time we inhale contaminated air, our body system will pay for it directly or indirectly. We may manage to live old despite all odds but what happens to the children in the coming generation?

Written by Iloyi Tomiwa. 

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