Back to: Jss1 Basic Science (BST)
Topic: Air POllution
WEEK: 7 & 8
All living things need to breathe in order to stay alive. We breathe the air that is in the air around us. So, if poisonous gases are in the air around us, they would kill us. Some of the most common air pollutants are sulphur dioxide, nitrogen dioxide, carbon monoxide, ozone, volatile organic compounds (VOCs), and airborne particles.
Meaning of Air Pollution
Air pollution is caused by putting harmful things into the air, which can make people and other living things sick or kill them.
Constituents of Air
Air is made up of 78% nitrogen, 21% oxygen, 0.9% oxide gases, and 0.1% gases that don’t react with anything. When this balance is upset, it causes problems that are very big.
Causes of air pollution
The major causes of air pollution are:
- Cars and factories give off gaseous oxides, such as nitrogen (II) oxide and carbon (II). These gases cause the ozone layer (the top layer of the atmosphere) to thin out, which makes the whole world warmer.
- Smog is another pollutant that comes from coal and fossil fuels that are used in homes and businesses. These pollutants hurt plants and buildings. They speed up the oxidation of iron and make it rust faster.
- The use of pesticides, insecticides, and fertilisers has caused a lot of ammonia to get into the air.
- Mining, the process of getting minerals out of the ground, sends dust and chemicals into the air, which makes the air dirty. Paper mills, steel mills, iron mills, cement plants, and asphalt plants all release aerosols, particulates, gases, and vapours into the air. Gases like ammonia, sulphur dioxide, hydrogen chloride, and hydrogen sulphide are put into the air by these mills and plants, which makes the air dirty.
Air pollution control
Air pollution is very dangerous to living things because almost all of them breathe it directly without filtering it first like water. So, using catalytic converters in cars, not burning used items, letting cars run for long periods of time while stopped, and other eco-friendly actions are important. Controlling air pollution can be done in two ways: by stopping particulate emissions and by stopping gaseous emissions. The word “particulate” refers to small pieces of matter like smoke, soot, and dust that are released by factories, farms, and other places. Industrial products like sulphur dioxide, carbon monoxide, and oxides of nitrogen are also released as gaseous emissions during different manufacturing processes.
- Particulate control: Most methods for controlling particles work on the same basic idea. Physical processes, such as moving the solid particles through a settling chamber, are used to separate them from the gases they are in. Gases from a manufacturing process flow through a long, wide pipe called a “settling chamber. As these gases move through the pipe more slowly, the solid particles fall to the bottom. Then they can be taken out of the pipe’s bottom.
- A cyclone collector: this is another device that can be used to get rid of particles in stack gases. The gases are placed in a round, turning container. Acid and oxide emissions can be completely cleaned up and controlled with the right equipment.
- Gaseous Emissions: Acid and oxide emissions can be completely cleaned up and controlled with the right equipment. Solid particles in the gas are pushed away from the centre of rotation by centrifugal forces, which are forces that move things away from the centre of rotation. They stay there for a short time before falling to the bottom of the container. The particles are then taken out of the gas, which comes out of the top of the container.
- Adsorption is another way to control gaseous emissions. Activated charcoal is charcoal that has been ground up into a very fine powder. In this form, charcoal can “adsorb,” or stick to, other chemicals. Unwanted gases are absorbed by activated charcoal on the inside of a smokestack when they flow over it. As with scrubbers, the charcoal is sometimes taken out of the smokestack and replaced with a new layer of charcoal.