Background
In November 2015, there was a fatality at a mine when a worker was exposed to high wet bulb temperatures in a poorly ventilated underground working area. Since then there have been other incidents of underground workers being affected by heat and requiring medical treatment – in one instance a worker became semi-conscious. In addition, mines inspectors have also reported deteriorating ventilation conditions at some underground mines raising concerns about the maintenance of thermal comfort and atmospheric contaminants below exposure standards.
From August 2016 the Department has been conducting unannounced inspections of underground ventilation systems. This has resulted in production and development in work areas being halted, issuing of prohibition and improvement notices and, in some instances, follow-up inspections.
Summary of hazard
Inadequate ventilation may lead to:
- an increase in temperature and humidity which reduces the cooling capacity of air, resulting in an elevation in the core body temperature and the onset of heat illness
- the inability to maintain atmospheric contaminants at levels below the exposure standard and as low as is reasonably practicable, exposing workers to a hazardous work environment with potential short- and long-term health effects. Contaminants include those from diesel emissions, gas outbursts, blasting fumes, dusts and fibrous materials.
Contributory factors
- Inadequate verification of the effectiveness of the ventilation design (e.g. comparing expected and actual performance).
- The limitations of ventilation designs not adequately understood, particularly their time dependent nature. For example, if new ventilation rises are not developed in a timely manner and fan installation delayed, the current design may not be able to deliver adequate ventilation to new headings.
- Inadequate ventilation design for work areas (e.g. air volume requirements for mining activity not being met).
- Inadequate training provided to workers and supervisors in the assessment of general atmospheric conditions and use of monitoring equipment.
- Workers not communicating to supervisors that they are operating in inadequately ventilated headings.