Lesson 7 of 11
Ozone depletion
Show on a big screenOld fridges once used a gas called CFC. What did that gas do, high in the sky?
Step 1 of 4
- Ozone sits in a thin layer, high in the air.
- The layer blocks most of the Sun's harmful UV rays.
- CFCs — gases once used in old fridges and some fire-fighting tanks — rise into this layer.
- CFCs break down ozone. A thinner layer lets more UV reach the ground.
Stop the at year 20. Drag the years.
Loading lab…
CFC gas thinned the layer. That layer blocks ultraviolet (UV) rays. UV is light from the Sun that we cannot see.
New words
- Ozone — a form of oxygen, O₃. It forms a thin layer high in the air.
- CFCs — gases once used in old fridges and some fire-fighting tanks. They break down ozone.
The rule
The layer blocks most of the Sun's harmful ultraviolet rays. CFC gases rise into this layer. They break ozone molecules apart, thinning the layer. A thinner layer blocks less UV.
Too much UV harms plants and animals. In people it can cause skin cancer. That is why a thinning layer worried scientists.
A 1987 agreement kept CFC output from growing past its 1986 level. New fridges use other gases. Scientists expect the layer to recover slowly, over decades.
Try the lab to finish this lesson.