1. Ozone Prevents UV-B radiation from reaching the Earth
Found in stratosphere
When O2 absorbs UV radiation it breaks down to O + O atoms
Free oxygen reacts with O2 to produce O3
O3 absorbs UV radiation and breaks down to O2 + O
This back & forth exchange, shields the Earth from the UV radiation
Relatively unstable-can break apart and the oxygen atoms can form other compounds very easily

2. CFC’s
Chlorofluorocarbons are inert – un-reactive, odorless , non-toxic, colorless, nonflammable, noncorrosive – and possess desirable properties as refrigerants, solvents, propellants.
Considered a dream chemical w/ no adverse human or environmental effects
PROBLEM AROSE WITH ITS
LOW REACTIVITY
Un-reactive in the troposphere, but when they reach the stratosphere they react with UV radiation
Relatively unstable-can break apart and the oxygen atoms can form other compounds very easily

3. CFC’s
UV radiation allows for the breaking off of a chlorine atom.This chlorine atom reacts with ozone
CFCl3 + UV ----- Cl + CFCl2
Cl + O3 - ClO + O2 repeats
ClO + O - Cl + O2 many times
Relatively unstable-can break apart and the oxygen atoms can form other compounds very easily

4. Ultraviolet radiation
UV-A has lowest energy, lowest potential for harming life. Not absorbed by the ozone layer
UV-B harmful to life, absorbed by the ozone layer, destruction of stratospheric ozone allows UV-B to pass through
UV-C highest energy. Breaks down oxygen molecules. Absorbed by oxygen in the atmosphere.
Relatively unstable-can break apart and the oxygen atoms can form other compounds very easily

5. Affects of ozone depletion
Higher amts. of UV rays reach the planet
Increased cases of skin cancers, cataracts, decreased immune systems
Decrease plant growth- crop damage and tall trees
Decreases phytoplankton populations (ocean productivity is reduced and fisheries are affected)
Reducing destruction
Eliminate uses of hydrocarbons/CFCs
Montreal Protocol
The hydrocarbons and CFCs remained unchanged in our atmosphere so when released they gradually drift up to the stratosphere and then chemically interact with ozone and other substances found in this layer (produced by refrigerators and air conditioners).
The CFCs release Cl which interacts with the ozone the most breaking it apart.
The destruction is much faster than natural processes can replace.
The cold weather causes the halogen molecules to be more reactive destroying even more ozone especially apparent over Antartica.
Most cases of skin cancers and cataracts have increased in countries near Antarctica
Montreal Protocol regulates the emissions of ozone depleting chemicals