Air, pollution and the atmosphere
Clean, dry air is mostly nitrogen and oxygen with a little carbon dioxide and noble gases. Burning fuels adds pollutants — carbon monoxide, oxides of nitrogen and sulfur, and particulates — and managing them is now a core part of the syllabus.
Key facts
| Topic | Maintaining Air Quality |
| Air | ~78% nitrogen, ~21% oxygen |
| Key pollutants | CO, NOₓ, SO₂, particulates |
| Fix | catalytic converters, cleaner fuels |
What air is made of
Clean, dry air is about 78% nitrogen and 21% oxygen, with small amounts of carbon dioxide, argon and other gases. Carbon dioxide, though minor, matters because it is a greenhouse gas tied to climate change.
The main pollutants
Carbon monoxide comes from incomplete combustion and is toxic. Oxides of nitrogen (NOₓ) form in hot engines and cause acid rain and breathing problems. Sulfur dioxide comes from burning sulfur-containing fuels and also causes acid rain. Particulates (soot) harm the lungs and dirty surfaces.Effects
These pollutants drive acid rain (which damages buildings, lakes and forests), respiratory illness, and — for carbon dioxide and methane — the enhanced greenhouse effect. Linking each pollutant to its source and its effect is the heart of this topic.
Reducing pollution
Catalytic converters in vehicles convert harmful gases into less harmful ones — carbon monoxide and oxides of nitrogen into carbon dioxide and nitrogen. Other measures include removing sulfur from fuels, using cleaner or renewable energy, and improving efficiency. Sustainability is a section heading in K324, so expect to evaluate such measures, not just list them.Frequently asked questions
What is clean air made of?
About 78% nitrogen and 21% oxygen, with small amounts of carbon dioxide, argon and other gases.
What are the main air pollutants?
Carbon monoxide (incomplete combustion), oxides of nitrogen (hot engines), sulfur dioxide (sulfur-containing fuels) and particulates (soot).
What does a catalytic converter do?
It converts harmful exhaust gases — carbon monoxide and oxides of nitrogen — into less harmful carbon dioxide and nitrogen.
Why is air quality emphasised in K324?
Sustainability is a core section of the syllabus, so you should be able to evaluate measures that reduce pollution, not just name pollutants.
G3 Chemistry, made clear
LearnUp teaches K324 Chemistry topic by topic, with practical drills and exam-format questions. Explore the programme on BrainBuzz.
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