Exposure limits for dust
From 1 September 2020, the occupational exposure limits (OEL) for respirable dust and respirable crystalline silica (RCS) are 1.5mg/m3 and 0.05mg/m3 respectively.
Queensland mining legislation states that exposure to dust particles must not exceed exposure limits. Workplace exposure limits or standards are airborne concentrations of a particular chemical or substance in the workers' breathing zone that should not cause adverse health effects or cause undue discomfort to nearly all workers.
Exposure limits do not identify a dividing line between a healthy or unhealthy working environment. Natural biological variation and the range of individual susceptibilities mean some people might experience adverse health effects below the exposure standard. Therefore, exposure limits establish a legal or advisory maximum upper limit.
Where exposure cannot be eliminated, all reasonable steps should be taken to minimise exposure to a level well below the exposure limit.
Exposure limits for dust in coal mines, mineral mines and quarries are provided below. Additional advice on interpretation of the standards is available in the Guidance on the interpretation of workplace exposure standards for airborne contaminants.
Exposure limits for dust in coal mines
| Hazardous substance | TWA (mg/m3) |
|---|---|
| Coal dust (containing < 5% quartz) (respirable dust) | 1.5 |
| Crystalline silica (including quartz, cristobalite, tridymite) (respirable dust) | 0.05 |
| Inhalable/inspirable dust | 10.0 |
| Other airborne dusts as recommended by Safe Work Australia | various |
Exposure limits for dust in mineral mines and quarries
| Dust type | TWA (mg/m3) |
|---|---|
| Crystalline silica (including quartz, cristobalite, tridymite) (respirable dust) | 0.05 |
| Inhalable/inspirable dust | 10.0 |
| Respirable dust | 5.0 |
| Other airborne dusts as recommended by Safe Work Australia | various |
Adjusting for longer work shifts
Exposure standards (8-hour time weighted average) may require adjustment when work shifts exceed 8 hours or the working week exceeds 5 days. This adjustment compensates for the greater exposure that occurs during the longer work shift as well as the decreased recovery time between shifts.
An appropriately qualified person, such as an occupational hygienist who has a sound understanding of the toxicology and pharmacokinetics of the substance, should determine whether an exposure standard should be adjusted, and if so how. For more information on adjustment of exposure limits, read: