Air Quality RevisionAir Quality Revision

The AtmosphereThe Atmosphere

The Earth is surrounded by an The Earth is surrounded by an atmosphere made up of:atmosphere made up of:– 78% Nitrogen78% Nitrogen– 21% Oxygen21% Oxygen– 1% Argon1% Argon– Plus Carbon Dioxide and water Plus Carbon Dioxide and water

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PollutantsPollutants

Human activity adds CO, COHuman activity adds CO, CO22, , carbon, NOcarbon, NOxx and SO and SO22 to the to the atmosphere.atmosphere.

Some of these are harmful to Some of these are harmful to humans or harmful to the humans or harmful to the environment.environment.

Combustion ReactionsCombustion Reactions

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

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Combustion ReactionsCombustion Reactions

Burning fossil fuels also produces;Burning fossil fuels also produces;– Carbon MonoxideCarbon Monoxide COCO(from incomplete oxidation of carbon)(from incomplete oxidation of carbon)– Sulfur Dioxide Sulfur Dioxide SOSO22

(from sulfur in the fuel)(from sulfur in the fuel)– Nitrogen MonoxideNitrogen Monoxide NONO– Nitrogen DioxideNitrogen Dioxide NONO22

(from nitrogen in the air inside an engine)(from nitrogen in the air inside an engine)

Remember that the number of atoms before Remember that the number of atoms before and after the reaction must be the same.and after the reaction must be the same.

This means that the tonnes of fuel we burn This means that the tonnes of fuel we burn end up in the atmosphere.end up in the atmosphere.

Where do pollutants Where do pollutants go?go? Particulate carbon is deposited on Particulate carbon is deposited on

surfaces making them dirty.surfaces making them dirty. Sulfur dioxide and nitrogen dioxide Sulfur dioxide and nitrogen dioxide

react with water and oxygen to make react with water and oxygen to make acid rain.acid rain.

Carbon dioxide is used by plants in Carbon dioxide is used by plants in photosynthesis.photosynthesis.

Carbon dioxide dissolves in rain water Carbon dioxide dissolves in rain water and sea water.and sea water.

Reducing PollutionReducing Pollution

Power StationsPower Stations Use less electricity.Use less electricity. Remove the sulfur from gas and oil.Remove the sulfur from gas and oil. Remove SORemove SO22 and carbon power station and carbon power station

flues.flues.CarsCars Lean burn engines.Lean burn engines. Low sulfur fuels.Low sulfur fuels. Catalytic Converters.Catalytic Converters. Emissions testing and legal limits.Emissions testing and legal limits. Public Transport.Public Transport.

Analysing DataAnalysing Data

Understand that individual cases do Understand that individual cases do not provide convincing evidence.not provide convincing evidence.

Understand why it is necessary to Understand why it is necessary to repeat a study to confirm it.repeat a study to confirm it.

Understand that a change in one Understand that a change in one factor at the same time as another is a factor at the same time as another is a ‘correlation’.‘correlation’.

However, a correlation does not mean However, a correlation does not mean one factor changing causes the other one factor changing causes the other to change.to change.