Introduction to Air Pollution
Introduced| English |
|---|
| Air pollution/eə pəˈluːʃn/ |
| fossil fuels/ˈfɒsl ˈfjuːəlz/ |
| primary/ˈpraɪməri/ |
| secondary/ˈsekəndəri/ |
| ozone/ˈəʊzəʊn/ |
What is in dirty air
- Air pollution 空气污染 is harmful stuff added to the air.
- It can be gases, tiny particles, or droplets.
- Most of it comes from burning fossil fuels 化石燃料.
- Cars, power plants, and factories are the biggest sources.
Primary pollutants
- A primary 一次 pollutant is released directly into the air.
- Carbon monoxide pours out of a car's exhaust.
- Sulfur dioxide leaves a coal power plant's smokestack.
- Soot and dust particles come straight from fires and engines.
Air pollution is…
Air pollution is any harmful substance added to the air — gases, particles, or droplets.
Secondary pollutants
- A secondary 二次 pollutant is not emitted directly.
- It forms in the air when primary pollutants react.
- Ground-level ozone 臭氧 forms when sunlight hits car exhaust.
- Acid rain forms when sulfur and nitrogen gases react with water.
Primary or secondary pollutant?
Sort each pollutant by whether it is emitted directly or forms later in the air.
A primary pollutant is one that…
A primary pollutant comes straight from the source — like CO from a tailpipe or SO2 from a smokestack.
A ____ pollutant forms in the air when primary pollutants react, like ozone in smog.
A secondary pollutant is not emitted directly — it forms in the atmosphere, like ground-level ozone.
Why the split matters
- Primary pollutants can be cut at the source — cleaner engines, scrubbers.
- Secondary pollutants need us to cut the primary ones that make them.
- You cannot filter ozone from a tailpipe — it isn't there yet.
- So controlling air pollution means understanding where each one comes from.
Burning fossil fuels is a major source of air pollution.
Cars, power plants, and factories burning fossil fuels are the biggest sources of air pollution.
Select all primary pollutants (emitted directly).
CO, SO2, and soot are emitted directly. Ground-level ozone is secondary — it forms in the air.
The key distinction: primary = emitted directly (you can trap it at the smokestack or tailpipe). Secondary = forms in the atmosphere from primary pollutants reacting, often with sunlight. Ground-level ozone is the classic secondary pollutant — no engine emits ozone; it's built in the air from exhaust plus sunlight.
A city morning:
- Rush-hour traffic pours out primary pollutants — carbon monoxide, nitrogen oxides, soot.
- As the sun climbs, its light drives those nitrogen oxides and vapours to react, building up secondary ground-level ozone.
- By midday the "smog" hanging over the city is largely a pollutant that no single tailpipe ever emitted.
Air pollution is harmful gases, particles, and droplets added to the air, mostly from burning fossil fuels. A primary pollutant is emitted directly (carbon monoxide, sulfur dioxide, soot). A secondary pollutant forms in the air when primary ones react — like ground-level ozone in smog. The split guides how we control each.