Air Pollution
Primary 6 · Science and Elementary Technology
Air Pollution
Lesson 2 of 4
14 min
Let's begin
Think about one ordinary day. Breakfast is cooked on a smoky firewood fire. On the way to school a bus puffs out black smoke. A neighbour is burning a pile of rubbish, a lorry raises dust on a dirt road, and a man is smoking at the bus stop.
That is five sources of air pollution before the first lesson has even started. Where does the dirt in our air come from?
Air pollution happens in two places: indoors, in homes and kitchens (called household air pollution), and outdoors, in streets, towns and the countryside.
| Source | What it puts into the air |
|---|---|
| Cooking with firewood and charcoal, especially on a three-stone fire in a kitchen without a chimney or window | Smoke, soot and carbon monoxide, right where people breathe. In countries where many families cook with solid fuels like wood and charcoal, indoor pollution is one of the biggest dangers to health. |
| Vehicle emissions from cars, buses, lorries and motos, especially old engines that are badly looked after | Black smoke, soot, carbon monoxide, nitrogen oxides and carbon dioxide. Busy Kigali roads at rush hour are the worst. |
| Industrial emissions from factories, brick kilns, cement works and mills | Smoke, fumes, dust and sulphur dioxide from tall chimneys. |
| Bush burning: setting fire to grass and crop leftovers to clear land | Thick smoke and soot that can spread over whole hillsides. |
| Burning rubbish, especially plastic | Poisonous fumes and black smoke. |
| Cigarette smoking | Tobacco smoke that harms the smoker and everyone nearby (second-hand smoke). |
| Dust from dirt roads, building sites and quarries | Dust that irritates eyes and lungs. |
| Natural sources | Gases and ash from volcanoes such as Nyiragongo, just across the border from Rubavu, and smoke from wildfires. |
In one Rwandan town, the air along the main road is smoky only between 7 and 9 in the morning and between 5 and 7 in the evening. Which source is it?
Matching the where and the when of the pollution to the source is how scientists track it down.
Rwanda has banned plastic bags since 2008, Kigali holds regular car-free days, vehicles are checked at inspection centres, and families are encouraged to cook with cleaner stoves and gas.
Tip
Where there is burning, there is pollution
Firewood, charcoal, petrol, diesel, rubbish, grass and cigarettes all have one thing in common: something is being burned.
Try each one first, then tap Show answer to check.
Name two sources of indoor air pollution in a home.
Answer: Any two of: cooking with firewood or charcoal, smoking inside, burning charcoal to keep warm, a kerosene lamp.
Why is black smoke from an old lorry a sign of a problem?
Answer: The engine is burning its fuel badly, so it releases extra soot and harmful gases. It needs repair.
Is a volcano a natural or a human source of air pollution?
Answer: A natural source.
Why is burning plastic worse than burning dry leaves?
Answer: Plastic gives off poisonous fumes as well as smoke.
What you learned today
Sources and credits
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
Quick check
Which of these is a natural source of air pollution?
