Nitrogen Oxides & Sulfur Dioxide

Source of nitrogen oxides (NOₓ)

Formed in car engines from reaction of nitrogen and oxygen at high temperatures

Examples of NOₓ

Nitrogen monoxide (NO) and nitrogen dioxide (NO₂)

Environmental effect of NOₓ

Causes acid rain and contributes to photochemical smog

Health effects of NOₓ

Respiratory irritation and breathing problems

Formation of sulfur dioxide (SO₂)

Burning fossil fuels containing sulfur impurities

Environmental effect of SO₂

Causes acid rain

Acid rain formation

SO₂ and NOₓ dissolve in rainwater to form acids

Acid rain effects on buildings

Corrodes limestone and marble

Acid rain effects on environment

Damages forests, kills aquatic life by lowering pH

Acid rain effects on humans

Irritates lungs and worsens asthma

Reducing SO₂ emissions

Remove sulfur from fuels before burning (desulfurisation)

Flue gas desulfurisation

SO₂ removed using calcium oxide or calcium carbonate

FGD products

Produces calcium sulfite or calcium sulfate (gypsum)

Reducing NOₓ emissions

Use catalytic converters in cars

Catalytic converter function

Converts NOₓ into nitrogen and oxygen

Key idea

NOₓ and SO₂ are major pollutants causing acid rain and health problems; both can be reduced by treatment technologies