1. Air Quality Revision

2. The Atmosphere The Earth is surrounded by an atmosphere made up of:
78% Nitrogen
21% Oxygen
1% Argon
Plus Carbon Dioxide and water vapour

3. Pollutants
Human activity adds CO, CO2, carbon, NOx and SO2 to the atmosphere.
Some of these are harmful to humans or harmful to the environment.

4. Combustion Reactions
When fuels burn carbon and hydrogen in the fuel react with oxygen to produce carbon dioxide and water. + + +

5. Combustion Reactions Burning fossil fuels also produces;
Carbon Monoxide CO
(from incomplete oxidation of carbon)
Sulfur Dioxide SO2
(from sulfur in the fuel)
Nitrogen Monoxide NO
Nitrogen Dioxide NO2
(from nitrogen in the air inside an engine)
Remember that the number of atoms before and after the reaction must be the same.
This means that the tonnes of fuel we burn end up in the atmosphere.

6. Where do pollutants go?
Particulate carbon is deposited on surfaces making them dirty.
Sulfur dioxide and nitrogen dioxide react with water and oxygen to make acid rain.
Carbon dioxide is used by plants in photosynthesis.
Carbon dioxide dissolves in rain water and sea water.

7. Reducing Pollution Power Stations Use less electricity.
Remove the sulfur from gas and oil.
Remove SO2 and carbon power station flues.
Cars
Lean burn engines.
Low sulfur fuels.
Catalytic Converters.
Emissions testing and legal limits.
Public Transport.

8. Analysing Data
Understand that individual cases do not provide convincing evidence.
Understand why it is necessary to repeat a study to confirm it.
Understand that a change in one factor at the same time as another is a ‘correlation’.
However, a correlation does not mean one factor changing causes the other to change.