Air pollutants

Sulphur dioxide (SO2)

What is sulphur dioxide?

Sulphur Dioxide (SO2) is a colourless gas with a characteristic sharp pungent smell mainly produced by the burning of fossil fuels containing sulphur.

What are the sources and contributors of sulphur dioxide?

SO2 is mainly produced when material containing sulphur is burned or heated in the presence of air. The largest source of SO2 in Auckland is from motor vehicles and industrial processes. When SO2 combines with water, it forms sulphuric acid, which is the main component of acid rain.

Sulphur Dioxide Pie Chart

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What are the effects of sulphur dioxide?

SO2 irritates the lungs, eyes and causes coughing, wheezing and breathlessness. Asthmatics are a particularly sensitive group who may suffer from breathing problems. SO2 can attach itself to other particles and if these are inhaled, they can cause more serious respiratory effects.

Standards/guidelines for sulphur dioxide

The guideline values in Auckland for SO2 are 350µg/m3 for a one-hour average and 120µg/m3 for a 24-hour period under the National Environmental Standards (NES)1.

View SO2 trends in Auckland.

1 Recent changes to the World Health Organisation ambient air quality guidelines mean that some New Zealand guidelines and standards are now out of date.