Experts Warn Against Too Much Exposure to Direct Sunlight - Effects of CFCs on Earth’s Ozone Shield - An Historic Treaty

Sep 29, 2026

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Advisories warn that excessive direct sunlight exposure can be harmful due to ultraviolet radiation. The text explains how chlorofluorocarbons (CFCs) break down in the upper atmosphere, destroying ozone, which normally absorbs UV and protects life on Earth. It summarizes evidence for ozone depletion, public and regulatory responses including U.S. and international CFC bans, and the health risks such as increased skin cancer. It concludes with the Montreal Protocol aiming to reduce CFC use and protect ozone levels.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages13

Reading Time33 min

AccessFree to download

Experts Warn Against Too Much Exposure to Direct Sunlight

How the ozone shield protects life

How CFCs destroy ozone

Banning CFCs and international action

An Historic Treaty

NationsAct ToSave0zoneShield # Experts Warn AgainstToo Much Exposure toDirect Sunlight Summer sunbathers should protect themselves from the sun's damaging uftraviolet rays. Far above the highest clouds,near thecold edge of space,something terrible ishappening.And if it is not stopped,itcould forever change life on Earth. forced to live in buildings or under-ground areas protected from outside light. CFC's By the early 1970's,scientists hadplenty of evidence that something waseating away at Earth's ozone shield.Butthey did not know what.At first they sus-pected natural causes such as changes insolar radiation.But as more informationcame in,especially from Earth satellites,the evidence pointed to man-made gasescalled chlorofluorocarbons(CFC's). What is happening is that somethingis destroying Earth's ozone shield.Theozone shield is a layer of gas surroundingEarth near the top of the atmosphere.Ozone is a rare form of oxygen that isformed when the sun's rays react withoxygen molecules high in the atmos-phere.Unlike ordinary oxygen,ozone hasthe ability to absorb the sun's ultravioletrays.Ultraviolet rays cannot be seen bythe human eye.But they cause sunburnand various forms of skin cancer. In the 1950's,60's,and 70's,CFC'swere a common ingredient in aerosolspray cans.They were also widely usedas coolants(chemicals used to lowertemperatures)in refrigerators and airconditioners.Each time a little bit of CFCgas was used-as when someone sprayedan aerosol can,for instance-CFC's es-caped into the atmosphere and rose slowlyupward.After 10 or 15 years,concentra-tions of CFC's reached the upper atmos-phere and mixed with the ozone shield. Without the ozone shield,scientists saythe full force of the sun's ultraviolet rayswould shower over Earth,killing mostplant life and thus causing animals andhumans to eventually die of hunger.Sucha blast of ultraviolet radiation could alsolead to an epidemic of skin cancer andother diseases.Any humans who sur-vived this onslaught would likely be P Once in the ozone shield,the CFC'sare broken down by the sun's rays to formchlorine and oxygen atoms.From labo-ratory experiments,scientists know thatchlorine atoms act much like chemicalsharks,attacking ozone atoms andbreaking them down.A single chlorineatom can destroy thousands of ozoneatoms at one time and can continue todestroy them for as long as 100 years. "For every chlorine atom you re-lease,"says a scientist,“100,000 mol-ecules o ozone are removed from theatmosphere." Banning CFC's In 1978,the U.S.became the first na-tion to ban CFC's in aerosol cans.Can-ada and several European countries soonfollowed with bans of their own.Butduring the 1970's,the rest of the worldactually increased CFCproduction.Thisled to further destruction of the ozoneshield-and to an increase in the amountof damaging ultraviolet radiation reach- ing the Earth's surface. According to the Environmental Pro-tection Agency(EPA),each 1 percentdrop in the ozone results in a 2 to 3 per-cent rise in the amount of ultraviolet lightreaching the Earth’s surface.This couldresult in as much as a 5 percent rise incases of skin cancer,says the EPA. In 1985,British scientists working inAntarctica discovered that the ozoneshield over that frozen continent may bedeteriorating faster than anyone realized.The scientists discovered that during Ant-arctic's spring,a giant hole formed inthe ozone shield directly over the SouthPole,depleting the ozone by as much as50 percent.Furthermore,this hole seemedto expand each year.Today it reaches asfar as populated areas of South America. # An Historic Treaty The world's growing concern about 薪DPR三 what was happening to the ozone shieldhas led to an historic treaty.The treaty,the first multination agreement dealingwith air pollution,was signed last Sep-tember in Montreal,Canada,by repre-sentatives of 31 nations.The treaty callsfor a 50 percent reduction in CFC use by1999.The ten-year time period will givemanufacturers ti

FAQs

What is the ozone shield and why does it matter?

The ozone shield is a gas layer near the top of Earth’s atmosphere that absorbs the sun’s ultraviolet rays. Without it, UV reaches the surface and harms living things, including causing skin cancer.

How do CFCs contribute to ozone depletion?

CFCs rise into the upper atmosphere and mix with the ozone shield. Sunlight breaks them down into chlorine atoms, which destroy ozone molecules for long periods.

What did the Montreal treaty require and when would it take effect?

The treaty calls for a 50 percent reduction in CFC use by 1999. It was set to go into effect on January 1, 1989, once most CFC-producing nations ratified it.

Sep 29, 2026

Uploaded by Ivy