Gas Hazard - a Silent Killer


On Waitangi Day in 2009, three young men went to work to clean an underground sewer in central Auckland.

They never came home.


Armed only with equipment to identify a lack of oxygen, the three didn’t stand a chance given the high levels of hydrogen sulphide present in the sewer and no means of detecting it.

They perished carrying out what should have been just a routine maintenance job.

Gas detection can be a life saver. With many gases being difficult, if not impossible to detect by smell or sight, a Gas Detector is the only way you can effectively identify the presence of dangerous gases before your workers go about their daily tasks.

Harmful gases can be caused by nature as well as by man. For example, chemical reactions within a peaty soil cause a build-up of gases which can be toxic during excavation.

So being aware of the natural creation of toxic gases will help you mitigate risk to your workers.

Man-made gas hazards can put your workers equally at risk, so understanding the environment in and around workspace is crucial to keeping them safe.

The best rule of thumb is: If in doubt, check it out.


Some cases where gas detection is required include:

  • Before entering any confined space – this can include sewers, manholes, water tanks etc (confined space entry is defined as an area not fit for human occupancy).
  • Anywhere it has been identified that atmospheric monitoring is required.
  • When working in open trenches, particularly where there is a peaty substrate.
  • Working in close confined quarters alongside machinery (such as diggers) with combustion engines that exude exhaust fumes.
  • Working around oxidising metals as corrosion can cause oxygen depletion.


...and many more.