Air pollution arises when particulates, chemicals or biological materials are introduced into the atmosphere tocause disease, physical unease or death to humans, crops or damage our natural environment .
The extent to which this pollutant deteriorates our health, crops and environment is alarming; we do hope we have a zero air pollutant someday. The principal agents of air pollution are explained below with health hazard they cause.
Particulate Matter
They are the total particulate matter suspended in the air, with additional subcategories of particles smaller than 10 μm in diameter and particles smaller than 2.5 μm in diameter. These particulate matters can exist in solid or liquid form, and includes smoke, dust, aerosols, metallic oxides, and pollen. They have their sources from factories, combustion, construction, agricultural activities, motor vehicles, and wood burning. Inhalation of enough particulate matter over time increases the risk of chronic respiratory disease.
Lead (Pb)
The largest source of Pb in the atmosphere has been from leaded gasoline combustion, but with the gradual elimination worldwide of lead in gasoline, air Pb levels have decreased considerably. Other airborne sources include combustion of solid waste, coal, and oils, emissions from iron and steel production and lead smelters, and tobacco smoke (source of lead in tobacco is Pb-210). Exposure to Pb can affect the blood, kidneys, and nervous, immune, cardiovascular, and reproductive systems.
Sulfur dioxide (SO2)
This compound is colourless, but has a suffocating, pungent odour. The primary source of SO2 is the combustion of sulfur-containing fuels (e.g., oil and coal). Exposure to SO2 can cause the irritation of lung tissues and can damage health and materials.
Nitrogen oxides (NO and NO2)
NO2 is a reddish-brown gas with a sharp odour. This gas is sourced primarily from the vehicle traffic, and it plays a role in the formation of tropospheric ozone. Large concentrations can reduce visibility and increase the risk of acute and chronic respiratory disease.
Carbon monoxide (CO)
Carbon monoxide is an odourless, colourless gas, formed from the incomplete combustion of fuels. Thus, the largest sources of CO today are motor vehicles, motor bikes and generators. Inhalation of CO reduces the amount of oxygen in the bloodstream (it competes with the oxygen in the blood stream), and high concentrations can lead to headaches, dizziness, unconsciousness, and death.
Ozone (O3)
Tropospheric (“low-level”) ozone is a secondary pollutant formed when sunlight causes photochemical reactions involving nitrogen oxides and volatile organic compounds. Automobiles are the largest source of volatile organic compound necessary for these reactions. Ozone concentrations tend to peak in the afternoon, and can cause eye irritation, aggravation of respiratory diseases, and damage to plants and animals.
If Ozone is a pollutant in the atmosphere, why do we have the ozone layer which absorbs direct harmful rays coming from the sun?
ReplyDelete