Working in oxygen-deficient atmospheres

Background

In 2012, WorkSafe observed an incident where mine workers experienced symptoms of oxygen deprivation after natural airflow ventilation was interrupted by rising water levels.

Because the lack of ventilation was not detected, the workers did not use their self-rescuers while exiting the mine on foot after their vehicles became inoperable in the oxygen-deficient atmosphere.

It is fortunate that the workers symptoms, which included light-headedness and increased breathing rate, did not lead to serious, long-term injuries.

Recommended control measures

Before work starts

Mine operators must ensure:

• safety management systems are in place, which include the maintenance of safe levels of ventilation both during and after the abandonment of mine working areas
• controls are in place to prevent thermal stress and the air throughout the mine is at a safe oxygen level and does not contain harmful levels of contaminants or impurities, and
• a thorough safety assessment is conducted that identifies mining hazards, including the potential for hazardous atmospheres, and that comprehensive risk control measures are documented and implemented.

In addition, mine operators should ensure:

• consideration is given to the removal of dewatering or associated infrastructure, which may have the potential to impact primary ventilation flow
• employees are aware of mine ventilation standards and requirements, and
• gas monitoring information and training is made available to workers for early detection of harmful gases or low oxygen levels when re-entering unventilated areas.

While undertaking work

Mine operators must ensure:

• active mine workings are routinely inspected
• gas monitoring information and training is made available to employees for early detection of harmful gases or low oxygen levels when re-entering unventilated areas
• employees are provided with and are competent in the use of self-rescuers and trained to assist in hazard identification
• there is a system to ensure all unused and unventilated workings are barricaded to prevent unauthorised access and control re-entry into the area.