WA mining pushes silicosis risk down to near zero

A new study in Occupational Medicine has found that respirable crystalline silica (RCS) exposures in the Western Australian mining industry are now so low that the risk of silicosis is negligible - even in job categories traditionally considered high risk.

Researchers from WorkSafe WA analysed more than 134,000 personal RCS exposure results recorded between 1986 and 2023. The data, drawn from across the state’s mining operations, showed a geometric mean exposure of just 0.008 mg/m³ - well below the current workplace exposure standard of 0.05 mg/m³. More than 90% of all results since 1986, and 96% since 2021, have been at or below this limit.

High-risk roles still well under danger levels

Exploration drillers’ assistants and laboratory workers recorded the highest average exposures - 0.020 mg/m³ and 0.015 mg/m³ respectively - but even in these roles, modelled steady-state lung silica burdens were 7.5 mg and 5.7 mg per lung. The study notes these values are an order of magnitude lower than the threshold linked to lung inflammation (150 mg/lung) and two orders of magnitude below that associated with fibrosis (1300 mg/lung).

“These are conservative estimates,” the authors write, noting the modelling assumes continuous exposure for entire shifts over multiple years without accounting for breaks, leave, or use of personal protective equipment - all factors that would further reduce actual lung burden.

A disease almost eradicated

Historically, silicosis was a serious problem in WA mining, with up to 100 cases a year recorded before tighter dust controls were introduced in the 1970s. In the decades since, the disease has become extremely rare in the sector. Since 1986 - representing more than two million person-years of mining work - only four confirmed and three possible cases have been identified. All were detected after 2021, when low-dose CT (LDCT) scans became mandatory for workers in roles with potential silica exposure.

By contrast, other industries have faced resurgences. The engineered stone sector, for example, has recorded over 500 Australian cases of silicosis since 2015, with measured RCS exposures sometimes more than 100 times those seen in WA mining.

Policy and practice pay off

The study credits the combination of strict regulatory oversight, industry compliance, improved dust control technology, and ongoing health monitoring with the near-elimination of silicosis in WA mining.

It also identifies where vigilance is still needed. Exploration work - particularly drilling - recorded four times the exposure exceedance rate of established mine sites. The authors recommend targeted monitoring and intervention in such roles, alongside continued LDCT screening to detect any early signs of disease.

The takeaway for industry

While the figures are encouraging, the research reinforces that low risk is not no risk. Certain workers may still face elevated exposures due to localised factors such as poor dust control, inadequate ventilation, or task-specific hazards. Ongoing training, monitoring, and compliance remain critical to ensuring WA mining’s record on silica-related disease continues to improve.