air pollution

• what happens when there's not enough oxygen available to do complete combustion?

  we get incomplete combustion. this can release carbon monoxide and particulates. particulates are solid particles of carbon (soot)
• what are the main problems with particulates?

  • if they're inhaled they can get stuck in your lungs and damage them. this can lead to respiratory problems.
  • they can form dark clouds or smog, which can direct sunlight back into space. this means less light reaches the earth. this is called global dimming.
• why is carbon monoxide dangerous?

  • if we breathe carbon monoxide in from the air it diffuses into our blood and binds to our haemoglobin, in the same place that oxygen binds
  • this means our haemoglobin can carry less oxygen meaning less oxygen gets carried around the body.
  • in severe cases this can lead to fainting, a coma and even death. this is because our brain becomes starved of oxygen
  • to make it worse, carbon monoxide is colourless and odourless, this makes it really hard to detect
• how is sulphur dioxide formed?

  sometimes the hydrocarbons we burn have impurities in then, like sulphur. so when we burn them the sulphur gets oxidised to sulphur dioxide gas.
• how is nitrogen oxide formed?

  when nitrogen and oxygen from the air react together. this doesn't normally happen because it requires really high temperatures for them to combine. howler these high temperatures are often reached inside internal combustion engines, like cars.
• what problems do sulphur dioxide and nitrogen oxide have?

  • when we breathe them in they can damage our lungs and cause respiratory problems
  • the bigger problem is that as these gases mix with clouds, they dissolve to form dilute sulphuric acid or dilute nitric acid. this then falls as acid rain. acid rain damages certain buildings and statues, corrodes metals and worst of all damages plants. this is either by landing directly on the plants or by making the soil more acidic, which can make it harder for the plants to grow