Vital Safety

vital | adjective | 1. critical, absolutely necessary 2. performing and essential function 3. characteristic of life

H2S Release in Water Well

The following article from WorkSafe WA highlights the dangers of H2S in confined spaces.  Unlike most confined space incidents, this worker survived but not by chance... by prepartion and planning! See alert

Hydrogen Sulphide (H2S) is a toxic gas that has the following properties:

  • Occurs naturally. Generated by bacteria.
  • Heavier than air
  • Easy to smell at low levels (0.05 ppm). Smells of rotten egg.
  • Deadens sense of smell at high levels (50 - 100 ppm)
  • Deadly health effects may be immeditate (respiratory paralysis) or delayed (pulmonary oedema)
  • Disolves in water.  May be released when water is disturbed.

How to Classify a Confined Space

The definition of a confined space can be unclear and confusing.  A confined space is not just an area where it is difficult to move.
When deciding the classification of spaces on a work site you should aim to be:

  • Consistent Realistic
  • Practical (consult employees)
  • Knowledgeable (confined space trained)


Before wasting time debating the classification, identify the potential hazards and decide on realistic controls for the space. Then compare the controls you have selected to the requirements of the confined space regulations... they may be the same.

Some sites use the definition "Restrictive Space".  This is used to describe an area that may become a confined space under certain conditions.

If confined space planning and preparation seems time consuming or too hard, maybe your site procedures need streamlining.  KEEP IT SIMPLE

See Article - aioh_conference_paper

Flammable Gas Under-estimate

A gas monitor may seriously under-estimate actual flammable gas levels.  This may occur if the target gas is different to the gas used for calibration. A correction factor can be applied to convert measured to actual levels. 

See Worksafe Alberta Bulletin  - LEL Correction

When sending your gas monitor for calibration, be sure to notify the service technician which flammable gas to use for calibration.  This will vary depending on the environment that the monitor is being used and will ensure the most accurate reading.  Some gas monitors allow users to change the flammable gas selection on-site.