Air pollution control sources may be accomplished by two fundamental approaches, which are categorized as control by dilution in the atmosphere by dispersion, or control at the source designed to reduce the air pollution emitted to the bared minimum.
Control by Dilution in the Atmosphere by Dispersion:
The most positive way to abate air pollution is to prevent it. However, if it does exist, smoke stacks are used to help reduced ground level concentration of pollutants by giving natural atmospheric turbulence an opportunity to dilute the pollutant before it reaches ground level receptors in harmful concentrations.
This approach controls emissions to some degree and may help obtain desired air quality, since the atmosphere has tremendous powers to dilute, disperse and destroy a large variety of substances that are discharged into it.
Control at Source:
Control at source may be accomplished by controlling the pollutant from coming into existence or by destroying, altering or trapping it before it reaches the atmosphere.
It is possible to determine a more satisfactory location for an industry that is causing unacceptable air pollution in its present location.
It is another method of control at source. A source may be shut down for a period of time if air pollution levels threaten public health.
Fuel or Energy substitution:
Fuel or energy substitution may be accomplished by replacing soft coal with hard coal, residual oil, distillate oil or natural gas. Fuel can be treated before combustion by desulfurising coal and fuel oil or by refining coal or natural gas to liquefied natural gas (LNG) or to liquid petroleum gas (LPG) which is free from sulphur.
When used, it will conserve energy as well as reduce pollution.
Good Operating Practices:
Equipment’s must be properly designed, installed, operated and maintained to minimize the emission of pollutants; for example, the introduction of excess liquid sulphur in the burner at a sulphuric acid plant, without enough excess air, may result in undue emission of sulphur dioxides.
Air Pollution Control Devices or Techniques:
The installation and operation of air pollution control devices or techniques are designed to destroy, mask, counteract or collect pollutants.
Control devices are generally designed to control either gaseous pollutants or particulate pollutants, since a few devices are efficient in the control of both.