Describe the role of stratospheric ozone.

Identify one method to reduce ozone-depleting substances.

Describe the formation of tropospheric ozone.

Evaluate one management strategy for urban air pollution.

Apart from global warming and ozone-depletion, state one pollution problem that may affect a number of countries.

absorbs (incoming) UV radiation;
UV radiation energy breaks bonds in O₂ and O₃ in the ozone layer and heats the atmosphere;
less UV radiation reaches the Earth’s surface/protects life from damaging effects of UV;

[2 max]

Any one of the following:
find substitutes for Ozone Depleting Substances (ODS);
ban ODSs;
international agreements, eg Montreal Protocol;
develop new technology, eg pump action aerosols;

[1 max]

oxides (eg NOx) from fossil fuel combustion;
react in sunlight with oxygen from air;

[2]

Strategies include: ban fossil fuel vehicles from urban areas, increase public transport, have pedestrian only areas;
eg increasing public transport;
reduces the number of vehicles on the road, so less emissions;
some cost to local government/investment in infrastructure;
long term gain from reduced fossil fuel emission is preferable to short-term costs;

Award [1] for pro, [1] for con, and [1] for concluding statement.

[3 max]

acid rain/deposition;
eutrophication;
oil spills;
nuclear accident/spill (eg Fukashima);
pesticides/plastics in international waterways/oceans;

Accept any other reasonable examples.
Do not accept global warming or ozone depletion.

[1 max]

Marks awarded varied widely. A significant number of responses only covered one marking point. There were also a number of no responses. There was sometimes confusion between the role of stratospheric ozone with tropospheric ozone and also with the greenhouse effect.

A large number of candidates answered this question adequately. A common error was to confuse ozone depleting substances with greenhouse gases emitted from combustion of fossil fuels.

This question was generally poorly answered. Candidates appeared to have little knowledge of the precursors and conditions required for formation of tropospheric ozone. There were a significant number of no responses to this question.

This question was well answered with most candidates achieving some marks. A common mistake was to list a number of strategies without any evaluation.

Responses were mixed to this question. Many answers were too vague e.g. water pollution or air pollution instead of being more specific such as acid deposition or eutrophication.