Burning fuels
- The combustion of fuels is a major source of atmospheric pollutants.
- Most fuels, including coal, contain carbon and/or hydrogen, and may also contain some sulfur.
- Gases released include carbon dioxide, water vapour, carbon monoxide, sulfur dioxide and oxides of nitrogen. Solid particles and unburned hydrocarbons form particulates (soot).
Carbon monoxide and particulates
- Carbon monoxide forms from incomplete combustion, when there is not enough oxygen.
- It is a toxic gas that is colourless and odourless, so it is not easily detected. It binds to haemoglobin, reducing the blood's ability to carry oxygen.
- Particulates cause global dimming (by reflecting sunlight) and health problems for humans, because they can get into the lungs.
Sulfur dioxide and oxides of nitrogen
- Sulfur dioxide forms when fuels containing sulfur burn.
- Oxides of nitrogen form when nitrogen and oxygen from the air react at the high temperatures in engines.
- Both cause respiratory problems and acid rain, which damages buildings, trees and aquatic life.
Reducing pollution
- Removing sulfur from fuels before burning, and scrubbers in power stations, reduce sulfur dioxide.
- Catalytic converters in cars change carbon monoxide and oxides of nitrogen into less harmful gases.
- Good ventilation and carbon monoxide detectors protect people at home.
Key terms
- Pollutant
- A harmful substance released into the environment.
- Carbon monoxide
- A toxic, colourless, odourless gas from incomplete combustion.
- Incomplete combustion
- Burning with too little oxygen, producing carbon monoxide and soot.
- Particulates
- Tiny solid particles, such as soot, released by burning fuels.
- Global dimming
- A reduction in sunlight reaching the Earth, caused by particulates.
- Sulfur dioxide
- A gas formed when fuels containing sulfur burn; causes acid rain.
- Oxides of nitrogen
- Gases formed when nitrogen and oxygen react at high temperatures in engines.
- Acid rain
- Rain made acidic by sulfur dioxide and oxides of nitrogen.