The document discusses the ozone layer, how it protects Earth from UV radiation, and how it has been depleted by man-made chemicals like CFCs. It describes the discovery of the ozone layer and the Antarctic ozone hole. The Montreal Protocol was created in 1987 to phase out the production of ozone-depleting substances and has been amended over time to accelerate this process. The consequences of ozone depletion include increased skin cancer and other health issues as well as harm to ecosystems.

1. Fortaleza, Joji Bryan
Manongdo, Marc Julian
Mercado, Chino Karmelo
Pilotin, Pamela Anne

2. Ozone Layer
 It is a layer in Earth's atmosphere which
contains relatively high concentrations
of ozone (O3).
 The ozone layer resides in the stratosphere
and surrounds the entire Earth.
 It was discovered in 1913 by the French
physicists Charles Fabry and Henri Buisson.

3.  Ozone is constantly produced from O2
molecules because of its reaction with UV
light.
 O2 molecules are more scattered because
the stratosphere has less air.
 Stratospheric ozone protects us from excess
UV but ozone in the lower atmosphere is
an air pollutant with harmful effects on the
respiratory systems of animals and will burn
sensitive plants.

5.  UV-B radiation (280- to 315- nanometer (nm)
wavelength) from the Sun is partially absorbed
in this layer. As a result, the amount of UV-B
reaching Earth’s surface is greatly reduced.
 UV-A (315- to 400-nm wavelength) and other
solar radiation are not strongly absorbed by the
ozone layer.

6. Ozone Depletion
 The ozone layer can be depleted by free
radical catalysts:
 nitric oxide (NO)
 nitrous oxide (N2O)
 hydroxyl (OH)
 atomic chlorine(Cl)
 atomic bromine (Br)

7.  Concentrations of chlorine and bromine
have increased in recent years due to the
release of large quantities of man-made
organohalogen compounds, especially
chlorofluorocarbons (CFCs) and
bromofluorocarbons (BFCs).
 CFCs and BFCs are capable of surviving the
rise to the stratosphere due to their
stability, where Cl and Br radicals are
liberated by the action of ultraviolet light.

8.  The Chlorofluorocarbons are expelled into the
atmosphere by:
 Refrigeration
 Aerosol spray cans
 Air conditioning
 Foam insulation
 Cleaning agents
 Packing material
 CFCs were used in consumer products because
they were chemically stable and non-toxic, thus
it took decades before it was known to destroy
the ozone layer.

9.  Each radical is then free to initiate and
catalyze a chain reaction capable of
breaking down over 100,000 ozone
molecules.
 The breakdown of ozone in the stratosphere
results in the ozone molecules being unable
to absorb ultraviolet radiation.
 Consequently, unabsorbed and dangerous
UVB radiation is able to reach the Earth’s
surface.

10.  Though it is known that ozone is naturally
decomposed to O2, the presence of Cl atoms
in the stratosphere serves as a catalyst to the
breakdown of ozone thus making the rate of
decomposition faster.

11. The Ozone Hole
 The ozone "hole" is really a reduction in
concentrations of ozone high above the
earth in the stratosphere.
 It is defined geographically as the area
wherein the total ozone amount is less than
220 Dobson Units.
 The ozone hole has steadily grown in size
(up to 27 million sq. km.) and length of
existence (from August through early
December) over the past two decades.

12.  Each spring in the stratosphere over Antarctica
(Spring in the southern hemisphere is from
September through November.), atmospheric
ozone is rapidly destroyed by chemical processes.
 As winter arrives, a vortex of winds develops
around the pole and isolates the polar
stratosphere. When temperatures drop below -
78°C (-109°F), thin clouds form of ice, nitric
acid, and sulphuric acid mixtures. Chemical
reactions on the surfaces of ice crystals in the
clouds release active forms of CFCs. Ozone
depletion begins, and the ozone “hole” appears.

13.  Over the course of two to three
months, approximately 50% of the total
column amount of ozone in the atmosphere
disappears.
 At some levels, the losses approach 90%.
This has come to be called the Antarctic
ozone hole.
 In spring, temperatures begin to rise, the ice
evaporates, and the ozone layer starts to
recover.

14. Consequences of Ozone Depletion
 Every time 1% of the ozone layer is
depleted, 2% more UV-B is able to reach the
surface of the planet
 Human exposure to UV-B increases the risk of
the following diseases:
 Skin cancer particularly in Caucasians
 Cataracts
 Increased rates of malaria and other
infectious diseases.
 Suppressed immune system

15.  The environment will also be negatively
affected by ozone depletion.
 Physiological and developmental processes
of plants are affected by UVB radiation.
 Effects on animals will also be severe, and
are very difficult to foresee.
 Exposure to solar UVB radiation has been
shown to affect both orientation
mechanisms and motility in
phytoplankton, resulting in reduced survival
rates for these organisms.

16.  Solar UVB radiation has been found to cause
damage to early developmental stages of
fish, shrimp, crab, amphibians and other
animals. The most severe effects are
decreased reproductive capacity and
impaired larval development.
 Other ecosystems such as forests and
deserts will also be harmed
 Wind patterns could change, resulting in
climatic changes throughout the world.

17.  Increases in solar UV radiation could affect
terrestrial and aquatic biogeochemical
cycles, thus altering both sources and sinks
of greenhouse and chemically-important
trace gases e.g., carbon dioxide
(CO2), carbon monoxide (CO), carbonyl
sulfide (COS) and possibly other
gases, including ozone. These potential
changes would contribute to biosphere-
atmosphere feedbacks that attenuate or
reinforce the atmospheric buildup of these
gases.

18.  Synthetic polymers, naturally occurring
biopolymers, as well as some other materials
of commercial interest are adversely affected
by solar UV radiation. Any increase in solar
UVB levels will therefore accelerate their
breakdown, limiting the length of time for
which they are useful outdoors.
 Ozone depletion will also magnify the
effects of global warming.

19. The Montreal Protocol
 In 1985, the Vienna Convention established
mechanisms for international co-operation in
research into the ozone layer and the effects
of ozone depleting chemicals (ODCs).
 The first discovery of the Antarctic ozone hole
happened in 1985.
 The Montreal Protocol on Substances that
Deplete the Ozone Layer was negotiated and
signed by 24 countries and by the European
Economic Community in September 1987.

20.  The Protocol called for the Parties to phase
down the use of CFCs, halons and other
man-made ODCs.
 After a series of rigorous meetings and
negotiations, the Montreal Protocol on
Substances that Deplete the Ozone Layer
was finally agreed upon on 16 September
1987 at the Headquarters of the
International Civil Aviation Organization in
Montreal.

21.  The Montreal Protocol stipulates that the
production and consumption of compounds
that deplete ozone in the stratosphere--
chlorofluorocarbons (CFCs), halons, carbon
tetrachloride, and methyl chloroform--are to
be phased out by 2000 (2005 for methyl
chloroform). Scientific theory and evidence
suggest that, once emitted to the
atmosphere, these compounds could
significantly deplete the stratospheric ozone
layer that shields the planet from damaging
UV-B radiation.

22.  The Montreal Protocol on Substances that
Deplete the Ozone Layer is one of the first
international environmental agreements
that includes trade sanctions to achieve the
stated goals of a treaty. It also offers major
incentives for non-signatory nations to sign
the agreement. The treaty negotiators
justified the sanctions because depletion of
the ozone layer is an environmental problem
most effectively addressed on the global
level.

23.  Furthermore, without the trade
sanctions, there would be economic
incentives for non-signatories to increase
production, damaging the competitiveness
of the industries in the signatory nations as
well as decreasing the search for less
damaging CFC alternatives.
 At meetings in London (1990), Copenhagen
(1992), Vienna (1995), Montreal (1997) and
Beijing (1999) amendments were adopted
that were designed to speed up the phasing
out of ozone-depleting substances.

24. Summary of Montreal Protocol Control Measures
 ODS Developed Countries Developing Countries
 CFCs Phased out end of 1995 a Total phase out by 2010
 Halons Phased out end of 1993 Total phase out by 2010
 CCl4 Phased out end of 1995 a Total phase out by 2010
 Methyl chloroform Phased out end of 1995 a Total phase out by 2015
 HCFCs Freeze from 1996 b Freeze in 2016
35% reduction by 2004 Total phase out by 2040
65% reduction by 2010
90% reduction by 2015
Total phase out by 2020 c

25.  HBFCs Phased out end of 1995 Phased out end of 1995
 Methyl bromide Freeze in 1995 Freeze in 2002 at average
at 1991 base level d 1995-1998 base level
25% reduction by 1999 20% reduction by 2005 e
50% reduction by 2000 Total phase out by 2015
70% reduction by 2001
Total phase out by 2005
 a With the exception of a very small number of internationally agreed essential uses
that are considered critical to human health and/or laboratory and analytical
procedures.
b Based on 1989 HCFC consumption with an extra allowance (ODP weighted) equal to
2.8% of 1989 CFC consumption.
c Up to 0.5% of base level consumption can be used until 2030 for servicing existing
equipment.
d All reductions include an exemption for pre-shipment and quarantine uses.
e Review in 2003 to decide on interim further reductions beyond 2005.

27. Becoming Ozone Friendly
 All parts of our daily lives have been touched by
ozone-depleting substances. Prior to the
1980s, CFCs and other ozone-depleting substances
were pervasive in modern life. But thanks to the
work of individuals, businesses, organizations, and
governments around the world, substitutes that
are safer for the ozone layer continue to be
developed for many ozone-depleting substances.
The phase out of ozone-depleting substances has
also made a substantial contribution toward the
reduction in greenhouse gas emissions since their
global warming potential is very high.

28. Then: Ozone-depleting substances were all around us.
Now: More ozone-friendly products, better
processes, and new equipment are in use.
Computers
 Then: Solvents containing CFCs and methyl
chloroform were used to clean circuit boards
during their production.
 Now: Some companies have eliminated the need
to clean circuit boards during their production.
Others use water or have temporarily switched to
HCFCs.

29. Polystyrene Cups and Packing Peanuts
 Then: Some polystyrene cups and foam packing
“peanuts” were made using CFCs.
 Now: These products are made with materials
that do not deplete the ozone layer.
Aerosol Cans
 Then: CFCs were the propellant used in various
spray cans.
 Now: Pumps and alternative propellants using
hydrocarbons are being used.

30. Central Air Conditioners
 Then: CFCs were used as the coolant in
household air conditioners.
 Now: HCFCs and HFCs have replaced CFCs.
Degreasers
 Then: CFCs or methyl chloroform were used in
many solvents for degreasing.
 Now: Water-soluble compounds and hydrocar-
bon degreasers that do not deplete the ozone
layer are available for many applications.

31. Refrigerators
 Then: CFCs were used in refrigerator coolants and
foam insulation.
 Now: HFCs have replaced CFCs, and substitutes
are on the horizon that will have reduced
greenhouse gas impacts.
Car Air Conditioners
 Then: CFCs were used as the coolant in
automobile air conditioners.
 Now: HFCs have replaced CFCs.
Fire Extinguishers

32. Fire Extinguishers
 Then: Halons were commonly used in hand-held
fire extinguishers.
 Now: Conventional dry chemicals, which don’t
deplete the ozone layer, and water have replaced
halons. HFCs are also used.
Furniture
 Then: Foam-blowing agents containing CFCs
were used in furniture making.
 Now: Water-blown foam is being used.

34. Safety against UV
 Ultra-violet light (UV) is defined as
electromagnetic radiation in the spectral
region between 180 and 400 nanometers
(nm). Immediate or prolonged exposure to
UV light can result in painful eye injury, skin
burn, premature skin aging, or skin cancer.
Individuals who work with or in areas where
UV sources are used are at risk for UV
exposure if the appropriate shielding and
protective equipment are not used.

35. Some Sources
 Welding operations
 Biological laboratories where gels are visualized
 Areas in which germicidal UV lights are
used, including biological safety cabinets
 Libraries where UV light may be used to
examine documents
 Science laboratories where Mineralights are
used to cause fluorescence
 Mercury vapour lamps with broken or missing
envelopes

36.  The symptoms of UV overexposure to the skin
are well known and characteristically called
sunburn. However, the symptoms of
overexposure to the eyes are not widely
known. Symptoms are:
 a burning and painful sensation in the eye
 a sensitivity to light
 the sensation of a foreign object in the
eye, sometimes described as sand in the eye
 tearing

37. Protection
 The purpose of the UV Light Safety Program
is to ensure that the safeguards necessary to
limit exposure have been implemented.
 The key to effectively reducing UV exposure
is to properly shield the source and to
require that users wear the appropriate
personal protection. Personal protection
that is appropriate includes welder’s
masks, goggles and face shields.

38.  Protection from ultraviolet (UV) radiation is
important all year round, not just during the
summer or at the beach. UV rays from the sun
can reach you on cloudy and hazy days, as
well as bright and sunny days. UV rays also
reflect off of surfaces like
water, cement, sand, and snow. Indoor
tanning (using a tanning bed, booth, or
sunlamp to get tan) exposes users to UV
radiation.
 The hours between 10 a.m. and 4 p.m.
daylight savings time are the most hazardous

39. Safety Measures
 Seek shade, especially during midday
hours.
 Wear clothing to protect exposed skin.
 Wear a hat with a wide brim to shade the
face, head, ears, and neck.
 Wear sunglasses that wrap around and
block as close to 100% of both UVA and UVB
rays as possible.
 Avoid indoor tanning.

40.  Use sunscreen with sun protective factor
(SPF) 15 or higher, and both UVA and UVB
protection.
 Some make-up and lip balms contain some
of the same chemicals used in sunscreens. If
they do not have at least SPF 15, don't use
them by themselves.
 To reduce the harm from UV radiation, the
most important thing is to minimize direct
exposure of the skin and the eyes to
sunlight.