TOEFL ITP Reading set 026
Reading Comprehension practice — read the passage and choose the best answer.
การฟื้นตัวของโอโซนในสตราโตสเฟียร์
- Line numbers appear every 5 lines.
- Answer all 10 questions, then choose ตรวจคำตอบ to see the Thai translation, score summary, and explanation.
- Use Previous / Next to open the previous or next practice set.
Stratospheric ozone, a thin layer of O3 molecules high above
Earth's surface, absorbs much of the Sun's harmful ultraviolet
radiation before it reaches living tissues below. Without that
filter, rates of skin damage and certain eye injuries would rise.
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In the late twentieth century, scientists detected a seasonal
thinning over Antarctica—popularly called the ozone hole—linked
to chlorine and bromine released from chlorofluorocarbons and
related industrial gases. Once those compounds drift upward,
solar ultraviolet light frees reactive halogen atoms that
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catalyze ozone destruction, especially on polar stratospheric
clouds that form in the cold polar night. The discovery spurred
the Montreal Protocol, a landmark international agreement that
phased out production of the worst ozone-depleting substances
and later tightened controls on substitutes that still posed
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smaller risks to the protective layer.
Decades of satellite and balloon measurements now show that the
decline has largely stopped and that Antarctic springtime ozone
is beginning a slow recovery. Models attribute most of the
improvement to falling stratospheric chlorine loading rather than
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to short-term weather noise. Recovery is not uniform, however:
volcanic aerosols and unusually cold winters can still deepen
temporary losses, and illegal or poorly regulated emissions of
banned chemicals occasionally appear in monitoring data. At
mid-latitudes, column ozone has risen more modestly, so public
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health messaging still emphasizes sunscreen and shade during peak
UV hours for outdoor workers and students alike.
Researchers also note that climate change complicates the
timeline. Greenhouse gases cool the stratosphere even as they
warm the surface, and a colder polar stratosphere can favor the
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icy clouds that accelerate ozone loss. Policy makers therefore
treat ozone recovery as a success story that remains unfinished:
continued compliance, careful tracking of new chemicals, and
coordination with climate policy are all required if the
protective shield is to approach pre-1980 levels later this
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century.