The Atmosphere and Environment

The Atmosphere and Environment

1. Pollutants

   • Particulates
   • Air pollutants
     • Carbon monoxide
     • Oxides of nitrogen
     • Ozone
     • Methane
     • Sulfur dioxide
     • Unburnt hydrocarbons

2. Sources of pollutants

   • Carbon monoxide
     • Mainly caused by incomplete combustion of petrol in car engines
   • Sulfur dioxide
     • Produced when fossil fuels such as coal, crude oil and natural gas are burnt in motor vehicles, power stations and factories OR in large quantities during volcanic eruptions
   • Oxides of nitrogen
     • Nitrogen combines with oxygen in the air to form nitrogen monoxide or nitric oxide in a car engine or chemical factory, where temperatures are very high OR when heat energy is released during thunderstorms. Nitrogen monoxide reacts with oxygen to form a brown gas, nitrogen dioxide.
   • Unburnt hydrocarbons, methane & ozone
     • Unburnt hydrocarbons are released in car exhaust fumes and chemical plants
     • Methane is produced when plant and animal matter decay OR from the decay of rubbish in landfills OR Sheep and cows give off methane due to digestion of food
     • Ozone is formed when nitrogen dioxide in the air reacts with unburnt hydrocarbons I'm the presence of sunlight

3. Effects of pollutants

   • Carbon monoxide
     • Reacts with haemoglobin in blood to form carboxyhaemoglobin, which reduces the ability of haemoglobin to transport oxygen to the rest of the body
     • Causes headaches, fatigue, breathing difficulties & even death
   • Sulfur dioxide & oxides of nitrogen
     • Irritate the eyes and lungs and cause breathing difficulties
     • High levels lead to inflammation of the lungs (bronchitis)
     • React with water in the atmosphere to form acid rain, which corrodes buildings and harms aquatic life and plants
   • Unburnt hydrocarbons
     • Cause cancer (carcinogenic)
     • React with nitrogen oxides to form ozone
   • Methane
     • Is a greenhouse gas, which causes global warming
   • Ozone
     • Forms photochemical smog, which irritates the eyes and lungs and causes breathing difficulties
     • Damages crops

4. Preventive measures

   • Reducing air pollution
     • Catalytic converters help remove pollutants in vehicle exhaust gases such as oxides of nitrogen, carbon monoxide and unburnt hydrocarbons by passing hot exhaust gases over the platinum and rhodium catalysts in a catalytic converter. The harmful pollutants are converted into harmless substances by redox reactions
     • Flue gas desulfurisation removes sulphur dioxide from waste gases formed when fossil fuels undergo combustion
     • Banning CFCs worldwide will help to prevent more CFCs entering the atmosphere and causing the depletion of the ozone layer
     • Prohibiting the use of open fires for the disposal of domestic and industrial waste, using unleaded petrol in place of leaded petrol, reducing the permissible level of sulphur in diesel & fitting petrol-driven vehicles with catalytic converters
     • Burn less fossil fuels, use new materials such as lightweight alloys to make car bodies, use clean fuels such as methanol and hydrogen and use electric cars