Causes of Atmospheric Pollution (AQA GCSE Chemistry Combined Science): Revision Notes
Atmospheric pollution
What causes atmospheric pollution?
When we burn fuels, they release many different substances into the air. Most fuels are made of carbon and hydrogen. Some fuels also contain sulphur. When these fuels burn, they create a wide range of pollutants that harm our atmosphere.
Fuel combustion is one of the biggest sources of air pollution. This happens in car engines, power stations, and heating systems.
Pollutants from burning fuels
When fuels burn, they release several harmful substances that affect both human health and the environment:
The main pollutants are:
- Carbon monoxide (CO) - a toxic gas
- Carbon dioxide (CO₂) - a greenhouse gas
- Sulfur dioxide (SO₂) - causes acid rain
- Oxides of nitrogen (NO and NO₂) - cause breathing problems and acid rain
- Particulates (soot) - tiny black particles
- Unburnt hydrocarbons - waste fuel that didn't burn properly
- Water vapour (H₂O) - not harmful, but produced during combustion
Cars are a major source of these pollutants. The exhaust pipe releases all these substances into the air every time we drive.
Health problems caused by pollutants
Different pollutants affect human health in various ways, with some being more dangerous than others.
Carbon monoxide (CO)
Carbon monoxide is extremely dangerous because:
- It's colourless and odourless - you can't detect it
- It's toxic - it stops your blood carrying oxygen properly
- It combines with haemoglobin in your blood instead of oxygen
- This prevents enough oxygen getting around your body
Sulphur dioxide (SO₂) and nitrogen oxides
These gases cause several serious health and environmental problems:
- Breathing problems - they irritate your lungs
- Acid rain - they dissolve in rainwater and make it acidic
- Acid rain damages plants and buildings
Particulates (soot)
These tiny particles are small enough to penetrate deep into your respiratory system:
- Damage your lungs when you breathe them in
- Cause breathing problems
- Create global dimming - they reflect sunlight away from Earth
Environmental effects
Air pollution doesn't just affect human health - it also has serious consequences for our environment.
Acid rain
Acid rain is a major environmental problem caused by air pollution:
- Caused by sulphur dioxide and nitrogen oxides
- Damages forests and crops
- Corrodes stone buildings and metal structures
- Makes lakes and rivers too acidic for fish
Global dimming
This lesser-known effect occurs when pollutants interfere with solar radiation:
- Particulates in the atmosphere reflect sunlight
- Less sunlight reaches Earth's surface
- This reduces the amount of solar energy we receive
Key Points to Remember:
- Burning fuels releases many harmful pollutants into the atmosphere
- Carbon monoxide is the most dangerous - it's toxic and hard to detect
- Sulphur dioxide and nitrogen oxides cause acid rain and breathing problems
- Particulates cause lung damage and global dimming
- These pollutants harm both human health and the environment