Ozone layer depletion
From this we’ll
1. what is ozone layer, where does it occur and why is
2. The difference between good and bad ozone
3. effects of ozone layer
4. impact of it
Ozone (O3) is a highly-reactive from of oxygen.
Unlike oxygen (O2), ozone has a strong scent and
is blue in color.
Ozone exists within both the tropospheric and
stratospheric zones of the Earth’s atmosphere.
In the stratosphere the ozone layer is an essential
protector of life on earth as it absorbs harmful UV
radiation before it reaches the earth.
Where is it found???
Ozone is trioxygen (O3)
Ozone is found in both the troposphere (lower
atmosphere) and the stratosphere
In the stratosphere the ozone forms a “layer”, this
layer is important as it protects us from UV radiation
– ozone is responsible for filtering a very high
percentage of UV radiation
Good and bad ozone
The ozone is the stratosphere is GOOD ozone as it
filters the UV radiation
Ground level tropospheric ozone is BAD ozone as it
can exacerbate asthma and cause other respiratory
and associated health problems
When you investigate urban microclimates and
pollution you will study ground level ozone
Ozone is continually created and destroyed within the
stratosphere (O+O2=O3+O=2O2+O=O3 etc.)
The total amount of ozone in the stratosphere is determined by
the balance between photochemical production and
This good ozone in the stratosphere can be destroyed by ozone
depleting substances (ODS)
ODS include chlorofluorocarbons (CFCs), hydro-
chlorofluorocarbons (HCFCs) and halons – these have
anthropogenic sources such as coolants in air conditioning
systems and propellants in aerosol sprays.
Whilst the source of much of the worlds ODS has been removed
(see Montreal Protocol below) it is worth remembering that 1
chlorine atom can destroy 100,000 molecules of ozone and these
chlorine atoms stay in the stratosphere a long time.
The ozone hole
Whilst CFCs and other ODS led to a depleltion in
global stratospheric ozone levels this was not
In the tropics no noticeable declines have been
recorded, whilst in middle latitudes declines of
between 3 and 6% have been measured.
Reactions that take place in polar stratospheric
clouds speed up the depletion of ozone – thus levels
of depletion of Antarctica (where such clouds are
common) were much faster than elsewhere.
This is where the concept of an “ozone hole” first
Impacts of ozone
Less ozone = more UV penetration into the
troposphere and lower atmosphere
The most serious human impacts are skin cancer and
Increased tropospheric UV radiation can lead to
greater levels of BAD tropospheric ozone
High levels of UV can also affect rice and plankton
Ozone depletion causes increases in UV
rays' effects on aquatic ecosystems by:
1. decreasing the abundance of phytoplankton –
affects the food stock for fishes and the
absorption of CO2
2. decreasing the diversity of aquatic organisms –
reduces food stock and also destroys several
fish and amphibians
Damage to plant cell DNA molecules - makes
plants more susceptible to pathogens and
Reductions in photosynthetic capacity in the
plant - results in slower growth and smaller
Causes mutations in mammalian cells and
Effects on humans
Premature aging (photo aging) of the skin (different from
normal chronological aging)
Cataracts and eye disorders (corneal sunburn and
Immune system damage
There are many possible solutions to this problem, but it
wholly relies on us, humans.. The following are the soltuions
for decreasing the ozone hole in the atmosphere:-
Firstly the consumption all the cfcs should be stopped.
Companies should be held responsible for the disater they
are causing in the environment
And we should use the 3rs…. Which are reuse , recycle,
reduce initiative… so that the next generation doesnot
have to go through problems made by us.
And the use of cfcs should be ban