OZ 1 

• From top to bottom the atmosphere layers of the earth are.
  Thermosphere
  Mesosphere
  Stratosphere
  troposphere

==Gas Main source as result of human activity’s==

Carbon dioxide - Combustion of hydrocarbon fuels

Methane - Cattle farming, landfill sites

Nitrous oxides - Fertiliser, changes in land use

Carbon monoxide - Incomplete combustion of hydrocarbons

Nitrogen oxides - internal combustion engines

• Carbon dioxide was converted into oxygen by plant and algae via a process of photosynthesis
• Methane reacted with oxygen into carbon dioxide before being turned into oxygen by photosynthesis
• Ammonia reacted with oxygen to form nitrogen
• ==Ppm = parts per million==
   To convert parts per million to a percentage you divide by 10,000