Ozone and the Ozone Layer


Ozone is a kind of oxygen in which each molecule has three atoms instead of two. The formula is O3 . Ozone is often produced when electricity passes through the air. That is why there is often an unpleasant smell after a thunderstorm or around electrical equipment .

Ozone is a blue gas that is explosive and poisonous .It is denser than oxygen and condenses into a dark blue liquid at - 112° C. This liquid freezes at – 251° C.

Ozone is used in many industries. Factories use it for chemical reactions because it reacts more easily than oxygen does. Ozone also kills germs , which makes it useful for removing bad smells and sterilizing drinking water. Ozone is also used to bleach color out of other substances .

Ozone occurs in our atmosphere in two forms. Near the ground even small amounts of ozone can cause health problems. It irritates your eyes and can lead to coughing and asthma . Ozone is especially dangerous on clear days when exhaust fumes or cars pollute the air. Older people and babies are often told to stay indoors because ozone may weaken your immune system .

About 30 -50 km above the Earth’s surface there is a layer of ozone in the atmosphere that protects us. It absorbs harmful ultraviolet rays from the sun. If too much of this radiation reaches the Earth it may injure your eyes and lead to skin cancer and other diseases .



In the 1970s scientists found out that chemicals released into the atmosphere have been destroying this ozone layer . The first hole in the ozone layer was found over Antarctica. In the last 20 years this hole has been getting bigger and now lies over some parts of Australia, New Zealand and the northern hemisphere as well.

The hole in the ozone layer is caused by CFCs , chemicals often used in spray cans and refrigerators . They escape into the atmosphere and break up the ozone molecules.



Related Topics



  • absorb = take in
  • amount = quantity, how much of something
  • asthma = if you have difficulty breathing
  • bleach = to make something pale or white
  • cause = lead to
  • CFC = gas used in refrigerators and spray cans; scientists believe it destroys the ozone layer
  • condense = to turn into a liquid
  • dense = thick
  • destroy = damage completely
  • disease = illness
  • electricity = the power that is in wires and cables; it gives us light and heat and makes machines work
  • equipment = machine and other tools
  • escape = get away into
  • especially = above all
  • exhaust fumes = the gases that are produced when a car is running
  • explosive = it can explode
  • factory = place where products are made
  • germ = bacteria; small living things that can make you ill
  • hemisphere = half of the earth
  • immune system = the system that helps your body protect itself against diseases
  • indoor = inside the house
  • injure = hurt
  • irritate = your eyes get red and you have to rub them because they hurt
  • liquid = fluid, something water
  • occur = happen
  • oxygen = a colourless gas that is in the air ; it is necessary for animals and plants to live
  • ozone layer = the part of the atmosphere that keeps harmful rays from reaching us
  • poisonous = it can lead to death if it gets into your lungs or body
  • pollute = to make dirty
  • protect = defend, guard
  • radiation = energy that is sent out as waves that you cannot see
  • refrigerator = machine that keeps food cool
  • release = let free
  • remove = take away
  • scientist = a person who is trained in science
  • skin cancer = a disease in which skin cells start to grow in a way that is not normal
  • sterilize = disinfect, purify, to make clean
  • substance = material
  • surface = the top layer of an object
  • thunderstorm = storm with thunder and lightning
  • ultraviolet ray = light that comes from the sun and makes your skin darker
  • unpleasant = bad
  • weaken = to make weaker