Reading Comprehension

PT146 · S4 · P4 · Q25 Chlorofluorocarbons and the Ozone

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By 1970 it was well established that ultraviolet light from the sun contributes to skin cancer.

Topic

The effects of chlorofluorocarbons (CFCs) on ozone depletion and the resulting public policy response.

Framework

Problem / Solution

Main Point

Molina and Rowland discovered that CFCs deplete the ozone layer, which protects us from cancer-causing ultraviolet radiation, prompting international policy change to control these pollutants. (Paragraph 2) This is wrapped up in Paragraph 4, where it summarizes the outcome:

P1: Importance of the Ozone Layer

By 1970, it was understood that ultraviolet radiation from the sun can cause skin cancer, but thankfully Earth's ozone layer filters out much of this harmful radiation.

P2: Discovery of the Ozone Problem

Scientists Molina and Rowland revealed that man-made chemicals called CFCs, found in products like aerosols and refrigerants, break down in the upper atmosphere and release chlorine, which destroys ozone. A single chlorine atom can wipe out thousands of ozone molecules.

P3: The Lasting Threat and Call to Action

Their research showed that even if we stopped using CFCs immediately, the chemicals already present would keep damaging ozone for many years. Molina and Rowland pushed for urgent public policies to address this environmental danger, leading to political attention and involvement in research committees.

25.

Which one of the following statements is most strongly supported by the information in the passage?

  1. Little or no ozone destruction

    Too Strong: little or no

    We are being told that chlorine is terribly damaging to ozone in the stratosphere. We're never told it's the only thing that destroys ozone in the stratosphere. This is playing the age old trick of acting like "Only Thing Mentioned = Only Thing". We're actually told in the 2nd sentence of the 2nd paragraph that in its natural state, the ozone layer was "natural production and destruction in rough equilibrium". So there are other things that destroy ozone, but they are offset by natural production of more ozone.

    12% picked this

  2. Skin cancers occur primarily because

    Too Strong: primarily

    We are told in the first sentence that UV radiation contributes to skin cancer. We're never told it's the #1 source skin cancer. This is acting like like "the only cause of skin cancer Mentioned = the #1 cause of skin cancer".

    4% picked this

  3. Few chemicals besides CFCs can

    Too Strong: few

    We are told that CFC's can break down and result in the release of chlorine in the upper atmosphere. We're never told it's one of the only things that can result in chlorine in the upper atmosphere. Just because the passage only mentions CFC's releasing chlorine doesn't mean we get to act like CFC's are "one of only a few things" that release chlorine.

    5% picked this

  4. Correct

    Regulating the use of CFCs

    Why this is right

    Regulating the use of CFC's contributes to keeping the ozone layer as a functional shield against incoming UV light from the sun. UV light from the sun contributes to skin cancer. So this is giving us a little causal chain: Regulate ? stronger ? less UV ? less skin CFC's ozone layer gets thru cancer When we say "A causes B, which causes C", then we can say that A directly caused B and indirectly caused C.

    Skill tested: Inference · how this choice captures the passage's function is the move to repeat next time.

    77% picked this

  5. The upward flow of CFCs

    Too Strong: mainly

    We were told that the hole in the ozone layer was discovered in Antarctica, but that doesn't mean that's where the upward flow of CFC's mainly happens. The atmosphere may be thicker by the equator and thinner by the poles, which could account for why the hole first showed up near the South Pole. We are told in the 2nd paragraph, studying two freon gases - types of CFCs - they observed that, when released into the lower atmosphere, these gases slowly diffuse upward into the stratosphere. Nothing in that "diffuse upward" detail is saying anything about "mainly in Antarctica".

    3% picked this

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