Preventing harm from hydrogen sulphide


Hydrogen sulphide (H₂S) is a highly toxic, colourless gas which occurs in a variety of natural and industrial settings. This quick guide provides information on the risks and effects of exposure to hydrogen sulphide, where it can be found, and how to manage the risks.

What this guide is about

This quick guide is for any persons conducting a business or undertaking (PCBUs) whose work may expose workers and other people to hydrogen sulphide.

PCBUs must ensure, so far as is reasonably practicable, the health and safety of workers and other people are not put at risk by their work.

In this quick guide, ‘you’ means the PCBU.

What is hydrogen sulphide and where can it be found?

What is hydrogen sulphide?

Hydrogen sulphide (H2S) is a highly toxic, colourless (transparent) gas which is heavier than air. The gas is corrosive and flammable.

Hydrogen sulphide can paralyse a person’s breathing system and kill in minutes. Even in small amounts, it can be dangerous to health.

Where can hydrogen sulphide be found?

Hydrogen sulphide is naturally occurring in geothermal areas and is emitted from volcanoes, undersea vents, swamps and stagnant bodies of water.

It is often a by-product of some industrial processes (see Table 1 below). It is important for PCBUs and workers to understand the risks or likelihood of exposure to hydrogen sulphide.

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New Zealand Worksafe, 27-10-22