Case study: exhaust fumes in a city
A case study: exhaust fumes, smog and how a city can reduce air pollution. Read one part at a time and tap “I know this”. Then test yourself in the quiz.
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Read the case study
Every morning thousands of cars crawl into Johannesburg, most with only one person. By 09:00, after the rush hour, a brown layer of smog hangs over the city. The problem: too many cars with one person each.
| Year | Cars per day at an intersection |
|---|---|
| 1990 | 2 000 |
| 2010 | 6 000 |
| 2025 | 10 000 |
From 1990 to 2025 the number rose by 8 000: more cars, more fumes. When horse carts gave way to cars, air pollution increased.
Solutions
- The Gautrain and Rea Vaya buses in Gauteng: fewer people drive their own cars. A full bus carries the most people for its fumes.
- Government can build good public transport and safe cycle lanes; cities plant trees along busy roads and hold car-free days.
- Thick black smoke from an old car: the engine needs fixing. Don’t drive to a shop you could walk to; don’t leave the engine running while parked for long.
Remember this and test yourself
- Exhaust fumes are the gases and smoke that come out of a car’s exhaust pipe when its engine burns petrol or diesel; mixed with fog or trapped in still air, they form smog.
- Cities have dirtier air because there are many more vehicles; traffic jams cause extra pollution.
- Carbon monoxide is poisonous with no colour or smell: never run an engine in a closed garage.
- Help: bus or train, a lift club, cycling, electric cars.
- Smog worsens asthma and makes eyes burn and water.
Write these points in your book. Read them again the night before the test.
One person per car = lots of smoke per person. A full bus = little smoke per person.
Important words
First say what the word means, then turn the card over.
Match column A to column B
Tap a word in column A, then its meaning in column B. You can also start in column B.
True or false?
Read the question and the answer. Is the answer right? Tap True or False.
Now the real quiz!
The quiz has many more questions on this topic. Every question shows straight away whether you are right and explains why.
Take the quiz: Case study: exhaust fumes in a city- Read one part together and ask your child to tell it back in their own words.
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Follows CAPS for Grade 4 Social Sciences (History). Always check your teacher’s notes and textbook too.