1. Sulphur Dioxide (SO2)
When it is in gas form, it is a toxic gas with a pungent, irritating and rotten smell.
Sulphur dioxide is used:
a. As a precursor to sulfuric acid.
* The major use of sulfuric acid is in the manufacturing of phosphate fertilizers.
b. As a preservative.
* Used as a preservative in dried fruits as it maintains colorful appearance of fruit and prevents rotting.
c. In winemaking.
* Serves as an antibiotic and antioxidant which protects the wine from spoilage by bacteria and oxidation.
d. As a reducing agent.
* In water, it decolorize substance. Reduces bleach for papers and clothes.
* In sewage management, it is used to treat chlorinated wastewater prior to being released.
e. As a refrigerant.
f. As a reagent and solvent in chemical laboratories.
As you can see, sulphur dioxide is widely used. Naturally, sulphur dioxide is released into the atmosphere after volcanic eruptions. But mass emissions from factories are worrisome because it contributes to air pollution.
Sulphur dioxide emissions are a precursor to acid rain. This causes the acidification of lakes and streams and speeds up the corrosion of buildings. Breathing in sulphur dioxide causes respiratory irritation and in weaker people, respiratory diseases. It can also cause difficulty in breathing. It also damages trees and crops.
Click on LINK to read more.
2. Nitrogen Dioxide (NO2)
This reddish-brown toxic gas has a sharp, biting odour.
Sources that contribute nitrogen dioxide are internal combustion engines, thermal power stations, pulp mills, butane gas heaters and stoves.
Nitrogen dioxide can irritate the lungs and lower resistance to respiratory infections such as influenza.
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3. Ground Level Ozone (O3)
Ground level ozone is the main component of smog. This ground level ozone and the atmospheric ozone are of the same chemical components. Ground level ozone is created by chemical reactions of nitrogen and volatile organic compounds (VOC). On very hot days combined with an urban environment (with lots of emissions from cars, factories, etc), ozone can reach very unhealthy levels. People with lung disease, sensitive people, children, old people and people who spend a great deal of time outdoors can be sensitive to this ozone.
Not only humans are affected by this, even animals and trees and vegetation can be harmed by ozone.
To read more about ozone, click on LINK.
4. Carbon Monoxide (CO)
In urban areas, carbon monoxide comes mainly from vehicles. Even poorly maintained generators produce carbon monoxide. Natural fires (forest and bush fires) and man-made fires (such as burning of crop residues, and sugar-cane fire clearing) contributes to the carbon monoxide production.
Carbon monoxide can cause harm to the health by reducing oxygen delivery to the body's organs (heart and brain) and also tissues. At very extreme levels, carbon monoxide can cause death.
5. Particulate Matter with a Diameter Below 10 Micrometers (PM10)
These are tiny pieces of solid or liquid particles which are suspended in the Earth's atmosphere. Some of these particles are natural as they originate from volcanoes, dust storms, forest and grassland fires, living vegetation and sea spray. Some are man-made as they are produced by the burning of fossil fuels in vehicles, power plants and the industrial sectors.
Small particles can stay in the atmosphere for weeks as they are small and light.
The manmade particulate matter affects the human health and also the climate of the Earth. These particulates can penetrate deep into the lungs and blood streams unfiltered and can cause DNA mutations, heart attacks and premature death. Lung cancer is the major concern. The WHO and IARC have labeled these particulates as a GROUP 1 CARCINOGEN. For a complete list of these particulates, click on LINK.
For more information on particulate matter click on LINK.
Below is the Malaysia's API Index measurement:
Air Pollution Level
|0 - 50||Good|
|51 - 100||Moderate|
|101 - 200||Unhealthy|
|201 - 300||Very unhealthy|
|301 - 500||Hazardous|
* taken from Air Pollution