Properties & Effects of Atmospheric Pollutants
Carbon Monoxide & Soot
- Carbon monoxide is an extremely poisonous gas as it combines with haemoglobin in blood and prevents it from carrying oxygen
- It is particularly malevolent as it is colourless and odourless, making it difficult to detect
- A lack of oxygen supply to the brain can lead to fainting, coma or in worst case scenarios, even death
- Solid carbon particles (or particulates) released from incomplete combustion clump together to form soot which gradually falls back to the ground
- Particulates can cause several problems:
- If they are inhaled they can damage the lungs and cause respiratory problems
- They can cover buildings and statues, making them look unclean and accelerating corrosion
- They can reflect sunlight back into space reducing the amount of light reaching the earth, this is called global dimming
Statues and monuments in very polluted areas become blackened over time from soot
Sulfur Dioxide
- Sulfur dioxide is a colourless, pungent smelling gas that is a major air pollutant responsible for acid rain
- The sulfur dioxide released mixes with clouds and readily dissolves in rainwater
- SO2 is a non-metal oxide so it forms an acidic solution in water, hence forming acid rain, H2SO4
- Acid rain causes corrosion to metal structures, buildings and statues made of carbonate rocks
- It causes damage to aquatic organisms, pollutes crops and water supplies, and irritates lungs, throats and eyes
Oxides of sulfur and nitrogen contribute to the formation of acid rain
Oxides of Nitrogen
- Oxides of nitrogen come largely from vehicle exhausts and also contribute to acid rain
- They are produced when nitrogen and oxygen react at high temperatures which are reached in a vehicle engine
- Aside from acid rain, oxides of nitrogen produce photochemical smog and breathing difficulties, in particular for people suffering from asthma
Exam Tip
Greenhouse gases and atmospheric pollutants are not the same thing. A greenhouse gas causes global warming whereas a pollutant is something which is not found in clean air and which causes problems close to the ground such as smog and breathing difficulties.
