What does the ozone layer in the stratosphere do that protects people at ground level?
Environmental impacts · EPA 608 Core. The correct answer, and the reasoning behind it.
How CFCs and HCFCs destroy stratospheric ozone, and what that does to health and the environment.
The question
What does the ozone layer in the stratosphere do that protects people at ground level?
- It filters smog and dust out of the air
- It traps heat near the surface to keep the earth warm at night
- It produces the oxygen that people breathe
- It absorbs much of the sun's ultraviolet radiationCorrect answer
Why “It absorbs much of the sun's ultraviolet radiation” is correct
Stratospheric ozone absorbs much of the ultraviolet (UV) radiation coming from the sun. When chlorine thins that layer, more UV reaches the surface, which is why ozone depletion is a health and environmental problem.
Source: EPA: Test Topics
Why the other answers are wrong
- It filters smog and dust out of the air — Smog and dust are lower-atmosphere pollution; the ozone layer does not filter them.
- It traps heat near the surface to keep the earth warm at night — Trapping heat is the greenhouse effect, a separate issue from ozone shielding.
- It produces the oxygen that people breathe — Breathable oxygen comes mainly from plants and plankton, not the ozone layer.
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