AirPollutants Emissions Essay

AirPollutants Emissions (% of total)
Natural Emissions
(% of total)
HumanProduced
1) Particulates 89 11
2) Sulfur Oxides (SOx) 50 50
3) Carbon monoxide (CO) 91 9
4) Nitrogen dioxide (NO2) Nearly All
5) Ozone (O3) A secondary pollutant derived from reaction with sunlight, NO2 and oxygen (O2)
6) Hydrocarbon (HC) 84 16
6.4.1.2. Type II Sorces of Air Pollution
The two major air pollution sources falling under this classification are
i) Stationary sources. ii) Mobile sources.
as shown in Figure 6.3.
Figure 6.3 Type II Classification of Air Pollution Sources
i) The stationary sources are those that have a relatively fixed location. These include.
(a) Point sources  Are stationary sources that emit air pollutants from one or more controllable points, such as smoke stacks of power plants.
(b) Fugitive sources Are stationary sources that generate air pollutants from open areas exposed to wind processes. Examples are dirt roads, construction sites, farm lands, storage piles, surface mines and other exposed areas from which particulates may be removed by wind.
(c) Area sources Are locations from which air pollutants are emitted from a welldefined area within which are several sources. e.g. small urban communities or area of intense industrialization within urban complexes or agricultural areas sprayed with herbicides and pesticides.
ii) Mobile Sources Are emitters of air pollutants that move from place to place while giving out emissions. e.g. auto mobiles, air crafts, ships and trains.
This type of classification of sources of air pollution is useful in air pollution modeling studies.
6.4.2. Classification of Air Pollutants
All air pollutants may be classified according to origin, chemical composition and state of matter as shown in Figure 6.4.
Figure 6.4 Classification of Air Pollutants based on Origin, Chemical Composition and State of Matter
A] Origin
(i) Primary pollutants  Are those emitted directly to the atmosphere and found there in the form in which they were emitted.
(ii) Secondary pollutants Are those formed in the atmosphere by chemical reaction in the presence of sunlight i.e. photochemical reaction or by hydrolysis or oxidation.
B] Chemical Composition
(i) Organic Organic compounds are those which contain C and H (may also contain elements such as oxygen, N, P, and S] Hydro carbons [ hexane, benzene, ethylene ] etc. contain only H and C while Aldehydes and Ketones [e.g. formaldehyde and acetone] contain C, H and O.
Organic pollutants may be natural or synthetic.
(ia) Natural organic pollutants are of biological origin e.g. pollens, microscopic algae, bacteria, viruses and the like that are alive or have just recently died. They are specifically called biological air pollutants.
(ib) Synthetic organic pollutants are those from manufactured products of nonbiological origin.
(ii) Inorganic materials found in contaminated atmosphere include carbon monoxides (CO), Carbon dioxide (CO2), Carbonates (CO3), Sulfur Oxides (SOx), Nitrogen Oxides (NOx), Ozone (O3), Hydrogen Fluoride (HF), and Hydrogen Chloride (HCl)
Chemical composition based classification of gaseous pollutants, as primary and secondary pollutants, is presented at Table 6.3