Dirty Air

Why it matters

The smoke from a truck and the smoke from a chimney quietly poison the air we breathe. But a row of trees and a simple filter can help clean it up again.

Predict first

Which of these is making the air DIRTIER rather than cleaner?

Vehicle exhaust adds carbon monoxide, smoke and other harmful gases, so it pollutes the air. Trees, converters and cleaner fuels protect it.

• Planting more trees along the road
• Black smoke pouring from a vehicle exhaust — correct
• Fitting a catalytic converter to a car
• Switching a bus to cleaner CNG fuel

What you do

Sort each one into things that POLLUTE the air or things that PROTECT the air.

Check yourself

Which pollutants dissolve in rain to cause acid rain that even eats away marble?

Sulphur dioxide and nitrogen oxides dissolve in rain to form acids. This acid rain damages marble buildings, such as the 'marble cancer' seen on the Taj Mahal.

Why is carbon monoxide such a dangerous air pollutant?

Carbon monoxide binds tightly to the blood so the blood can no longer carry enough oxygen, which is why it is poisonous.

What harm do CFCs from old fridges and air conditioners do?

CFCs rise up and break down ozone, thinning the ozone layer that normally shields us from the Sun's harmful ultraviolet rays.

• Sulphur dioxide and oxides of nitrogen — correct
• Oxygen and nitrogen
• Carbon dioxide and water vapour alone
• CFCs
• It is poisonous because it binds to the blood and stops it carrying oxygen — correct
• It makes the air smell bad but is otherwise harmless
• It turns rain acidic
• It thins the ozone layer
• They thin the ozone layer that blocks harmful UV rays — correct
• They make the air smell of chlorine but do no real harm
• They cause acid rain
• They add extra oxygen to the air