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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