1. Clean air?

2. Clean air?
The earth is surrounded by a mixture of gases called the atmosphere.
The atmosphere is made up of…
1.4%
20.6%
78%

3. It wasn’t always like this…
4.5 billion years ago.

4. 4.5 billion years ago…
Earth was a very violent place
It was just a ball of molten (hot) rock and minerals.
Very volcanic, which released gases into the atmosphere
The atmosphere was mainly
Carbon dioxide
Water vapour
Nitrogen

5. 4 billion years ago.

6. 4 billion years ago…
The earth is cooling down
Water vapour from the atmosphere condenses into oceans
The atmosphere was mainly
Carbon dioxide
Nitrogen

7. 3 billion years ago.

8. 3 billion years ago…
The first plant life appears
Algae appear on the water, and start to photosynthesise (make their food from sunlight)
This makes oxygen which goes into the air
The atmosphere was mainly
Nitrogen
Carbon dioxide
Oxygen

9. 2 billion years ago.

10. 2 billion years ago…
Proper plants evolved
There is more photosynthesis happening
This uses up more of the carbon dioxide and makes more oxygen which goes into the air
The atmosphere was mainly
Nitrogen
Oxygen
Carbon dioxide

11. Today!

12. Today…
Plants use up carbon dioxide from the atmosphere and add oxygen
People and animals use up oxygen and make carbon dioxide
People are cutting down trees a lot more – what do you think this will mean for the amount of carbon dioxide and oxygen?
The atmosphere is now
Nitrogen (79%)
Oxygen (20%)
Carbon dioxide and other gases (1%)

13. Complete the table using the information on the screen:
Time
Main Events
Atmosphere
4.5 billion years ago
Earth formed.
Violent volcanic eruptions.
Carbon dioxide
Water vapour
Nitrogen
4 billion years ago
Earth cools
Water condenses to form oceans.
2.5 billion years ago
Algae grow and begin to carry out photosynthesis.
Oxygen
2 billion years ago
Plants grow – pollute air with oxygen and remove carbon dioxide.
today
Humans can live on Earth
Nitrogen (79%)
Oxygen (20%)
Carbon dioxide and other gases (1%)

14. There are four main types of air pollution:
Carbon dioxide
Carbon dioxide comes from burning fuels.
It is a greenhouse gas and could be helping the earth to heat up (global warming).

15. Carbon monoxide
Carbon monoxide is made when fuels don’t burn properly.
It is a poisonous gas, and stops the body from being able to carry oxygen properly.

16. Nitrous oxides
Nitrous oxides are made when fuels burn at a very high temperature like in a car engine. They also help fuels to burn better, which is why racers use NOS in their cars!
They cause acid rain and smog, and can damage your lungs, especially if you have asthma. They are also greenhouse gases and damage the ozone layer.

17. Sulphur dioxide
Sulphur dioxide is made when fuels like coal, petrol and diesel burn. These fuels all contain some sulphur, which gets turned into sulphur dioxide.
It causes acid rain.

18. environmental impacts
pollutant
comes from?
environmental impacts
carbon monoxide
fuels not burning completely
poisonous gas, stops oxygen being carried round the body properly
nitrous oxides
fuels burning at a very high temperature like in an engine
acid rain, smog, asthma
sulphur dioxide
burning fossil fuels that have sulphur in them
acid rain
carbon dioxide
burning fossil fuels
greenhouse gas, heats up the earth

19. Catalytic convertors can help reduce pollution from cars by changing dangerous gases into harmless ones…

20. So why is clean air so important?
When making computers, it is very important the air is clean, because the electronic chips are so small.
Any dirt or dust could stop the equipment working properly.

21. People working with microchips have to use a clean room and wear special suits.

22. In an operating theatre the air has to be very clean – why?

23. Modern operating theatres are very clean – the air is usually cleaned with lots of filters. This helps to make sure there is no dirt or bacteria that could infect the patient.