With reference to Figure 9, explain why the highest levels of NO_x are found in the centre of London.

Evaluate one strategy to reduce NO_x emissions from transport.

Identify two potential impacts of improved air quality on London and its population.

1. burning/combustion of fossil fuels releases NO_x;
2. hence higher number of cars produces more NO_x;
3. greater use of public transport/buses generates more NO_x / use of diesel engines in buses produce more NO_x;
4. traffic congestion means that cars generate more NO_x;
5. tall buildings trap pollutants due to lack of air flow, resulting in higher levels of pollutants/NO_x;
6. large number of buildings/offices so more delivery trucks bringing supplies producing more NO_x;
7. there are fewer trees in central London that would trap NO_x and help lower NO_x levels;

Notes: Figure 2a states electricity is generated outside the city.
Do not accept there are more industry/factories in central London that generate NO_x.
Do not accept only ‘there are few green spaces/trees’, link needs to be made to trapping air pollutants/cleaning the air.

Examples of strategies include (N.B. no marks for stating strategy): use of congestion charges/higher tax for using cars, increase/shift to hybrid/electric cars, use of catalytic converters, increase public transportation / increase bicycles/free bicycle scheme, carpooling, shift to cleaner fuel sources for public transportation, stricter emissions controls on car exhaust, shift to solar powered cars/vehicles.

Conclusion [1 max] needs to consider both sides of the argument for credit. For Example 1, above, “while higher taxes may decrease the number of cars entering the city, this simply moves the problem into other zones around the centre, and therefore it is not an effective strategy.” 

Notes: Conclusion is not mandatory and [3] marks can be achieved through consideration of both advantages and disadvantages.
Do not award a mark for stating only strategy.
Accept other reasonable responses.

1. reduction in number of deaths due to air pollution / increase in life expectancy;
2. reduction in asthma/chronic bronchitis/respiratory ailments/lung disease/reduction in heart disease;
3. reduction in eye irritation/eye disease;
4. reduction in health care costs;
5. reduced heat island effect;
6. reduced damage to buildings/monuments;
7. reduced costs due to damage to monuments;
8. reduction in damage to plant tissue / increase in photosynthesis/plant growth/primary productivity;
9. increase in species diversity as high pollution levels have a detrimental effect on some species;
10. improves visibility in absence of smog/particulate pollution;

Notes: Doesn’t need to be one impact for London and one for population.
Do not credit only ‘improved health/reduction in diseases / reduction in photochemical smog / affects plants / better vegetation’.
Do not credit ‘less pollution would lead to greater tourism and increased revenues’.

Most candidates achieved at least one mark here for recognising that the high density of transportation in London contributed to the higher levels of NOx. Many responses only provided one or two reasons rather than the three required to achieve the three marks for this question.

Most students were able to give an appropriate strategy but in a significant number of responses there was no evaluation.

There were some very good responses to this question with many candidates achieving full marks. Common error was to give vague responses e.g. improves health or reduces disease.