IB ESS HL 8.3 Urban Air Pollution Questions

Practise IB ESS HL 8.3 by analysing pollutant cycles and evaluating photochemical smog, acid deposition and coordinated urban responses.

Exam points

Classify primary and secondary pollutants, then use PM2.5/NOx charts to explain urban emission peaks.
Trace fuel-combustion NOx/SOx through acid formation to nitric or sulfuric acid.
Read acid-deposition maps to link pH patterns with soil leaching, vegetation and freshwater damage.
Evaluate activity changes, emission controls or restoration, including international air-quality standards.
Explain ozone formation from NOx/VOCs in sunlight and how inversions, weak winds or topography trap smog.
Distinguish direct ozone harm to health, crops and materials from indirect healthcare and economic costs.

Covered syllabus points

8.3.1—Urban air pollutants 8.3.2—Primary pollutant sources 8.3.3—Fossil fuel combustion 8.3.4—Management strategies 8.3.5—Acid rain formation 8.3.6—Acid rain impacts 8.3.7—Acid rain management 8.3.8 (HL)—Photochemical smog 8.3.9 (HL)—Smog intensification factors 8.3.10 (HL)—Tropospheric ozone direct impacts 8.3.11 (HL)—Tropospheric ozone indirect impacts

[Maximum number: 10]

Figure 3: Concentration of atmospheric pollutants associated with photochemical smog

Figure:Concentration of atmospheric pollutants associated with photochemical smog

(a)

Identify one primary pollutant from the pollutants shown in the photochemical-smog pollutant chart shown above.

[ 1 ]

(b)

Outline why the pollutant named in Question 3 (a)(i) is referred to as a primary pollutant.

[ 1 ]

(c)

Outline one reason why there is an increase in nitrogen oxides and hydrocarbons early in the day.

[ 1 ]

(d)

Explain the changes in ozone concentration over the period shown in the photochemical-smog pollutant chart shown above.

[ 3 ]

(e)

State one environmental impact of the accumulation of ozone shown in the photochemical-smog pollutant chart shown above.

[ 1 ]

(f)

Outline two local conditions that may increase the severity of photochemical smog.

[ 2 ]

(g)

Outline the role of catalytic converters in reducing photochemical smog.

[ 1 ]

[Maximum number: 9]

Figure 3(a): Average hourly variation in ozone on wet and dry days in Guarujá, Brazil

Figure 3(b): Average hourly variation in NOx on wet and dry days in Guarujá, Brazil

Figure 3(c): Average hourly variation in SO2 on wet and dry days in Guarujá, Brazil

(a)

Identify the time of day that ozone is at its lowest concentration on a wet day in Figure 3(a).

[ 1 ]

(b)

Outline two reasons for the trend of hourly ozone concentrations shown in Figure 3(a).

[ 2 ]

(c)

Describe one impact of high $\mathrm{SO}_{2}$ concentrations on forest systems.

[ 1 ]

(d)

Outline one possible source of the pollutant shown in Figure 3(b).

[ 1 ]

(e)

Outline why $\mathrm{SO}_{2}$ levels are lower on wet days than on dry days, as shown in Figure 3(c).

[ 1 ]

$\mathrm{SO}_{2}$ dissolves in water / is removed from the atmosphere when it rains/forms acid rain;

(f)

Evaluate a strategy to manage the effects of one pollutant named in Figure 3(b) or Figure 3(c).

[ 3 ]

Example $\mathrm{NO}_{x} / \mathrm{SO}_{2}$ : replacing use of fossil fuels with alternative energy sources;
Advantage: it eliminates emission of pollutants altogether;
Disadvantage: it would involve major social changes that may be unpopular;
Appraisal: could be successful in a society that has strong ecocentric principles;
Example NOx: use of catalytic converters to trap emissions;
Advantage: would enable continued use of fossil fuels appropriate to popular technology;
Disadvantage: allows continued emission of other pollutants e.g. CO2/hydrocarbons;
Appraisal: would be relatively easy to introduce and enforce in a society;
Example $\mathrm{NO}_{x} / \mathrm{SO}_{2}$ : clean-up of acidified aquatic ecosystems using lime;
Advantage: relatively easy to apply / no requirement for popular cooperation;
Disadvantage: expensive and short term solution;
Appraisal: in the long run it would be better to remove root cause

Note: Allow 1 max for each valid e.g./advantage/disadvantage/appraisal up to 3 max.
Accept other valid strategies.

[Maximum number: 4]

With reference to named examples, distinguish between a primary and secondary pollutant.

primary pollutant is one which is active on emission / directly impacts the environment;
eg $\mathrm{CO}_{2}$ is released from burning fossil fuels and actively contributes to global warming / CFCs are released from aerosols and actively contribute to ozone depletion;
a secondary pollutant is one formed from a primary pollutant through physical/chemical change;
eg $\mathrm{CO}_{2}$ combines with sea water to form carbonic acid that leads to impacts on calciferous shelled organisms or corals / $\mathrm{NO}_{\mathrm{x}}$ combines with water to form acid precipitation / $\mathrm{NO}_{2}$ forms PAN/ozone (that contributes to photochemical smog);

Award [2 max] if no examples are given.
Examples of primary pollutants need to include their direct impact (eg $\mathrm{NO}_{x}$ can be either primary or secondary without such specification) and examples of secondary need to include the process leading to their polluting impact.
Award [1 max] for example of primary, and [1 max] for example of secondary.

[Maximum number: 1]

Figure 3(a): Average hourly variation in ozone on wet and dry days in Guarujá, Brazil

Figure 3(b): Average hourly variation in NOx on wet and dry days in Guarujá, Brazil

Figure 3(c): Average hourly variation in SO2 on wet and dry days in Guarujá, Brazil

Outline one possible source of the pollutant shown in Figure 3(b).

[Maximum number: 2]

Figure Ozone concentration by altitude in the atmosphere

Figure Percentage change in tropospheric ozone exposure 2010-2019

Outline two possible ways countries can reduce their tropospheric ozone exposure, as shown in Figure 2(b).

[Maximum number: 3]

Figure 2: Atmospheric sources and processes related to acid deposition

Figure:Atmospheric sources and processes related to acid deposition

Figure 2 shows some of the sources and processes that lead to acid deposition.

(a)

Burning fossil fuels produces gases often called $\mathrm{SO}_{\mathrm{x}}$ and $\mathrm{NO}_{\mathrm{x}}$ . State the names of the two acids usually produced when $\mathrm{SO}_{\mathrm{x}}$ and $\mathrm{NO}_{\mathrm{x}}$ dissolve in water.

[ 1 ]

(b)

Figure:European transport emissions of SOx and NOx from 1990 to 2007

Figure 3 shows the changes in European transport emissions of SOx and NOx between 1990 and 2007.

[ 2 ]

(i)

Compare and contrast the trends in transport emissions for SOx and NOx, shown in Figure 3.

[ 2 ]

[Maximum number: 1]

Figure 3(a): Average hourly variation in ozone on wet and dry days in Guarujá, Brazil

Figure 3(b): Average hourly variation in NOx on wet and dry days in Guarujá, Brazil

Figure 3(c): Average hourly variation in SO2 on wet and dry days in Guarujá, Brazil

Describe one impact of high $\mathrm{SO}_{2}$ concentrations on forest systems.

[Maximum number: 1]

Figure 2: Mean monthly regional changes due to the 2020 COVID-19 lockdowns in (a) NOx emissions and (b) tropospheric ozone concentrations

$\mathrm{NO}_{x}$ also contributes to acid deposition. State one method that could be used to restore an ecosystem damaged by acid deposition.

[Maximum number: 4]

Outline four factors that contribute to an increase in tropospheric ozone.

[Maximum number: 2]

Figure 2: Mean monthly regional changes due to the 2020 COVID-19 lockdowns in (a) NOx emissions and (b) tropospheric ozone concentrations

Tropospheric ozone is a major component of photochemical smog. Outline two conditions that contribute to high levels of photochemical smog in an area.

[Maximum number: 1]

Figure Ozone concentration by altitude in the atmosphere

Figure Percentage change in tropospheric ozone exposure 2010-2019

State one possible impact of increased ground-level ozone concentration on human health.

[Maximum number: 7]

Explain how urban air pollution could lead to significant economic losses.

All question bank results loaded

Covered syllabus points

Question 1

Question (a)

Question (b)

Question (c)

Question (d)

Question (e)

Question (f)

Question (g)

Question 2

Question (a)

Question (b)

Question (c)

Question (d)

Question (e)

Question (f)

Question 3

Question 4

Question 5

Question 6

Question (a)

Question (b)

Question (i)

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12