Titanium dioxide exposure in the Western Australian mining industry: Implications for compliance with current and proposed exposure limits

Titanium dioxide (TiO2) is widely used in mining and industrial processes and is generally considered to have low toxicity; however, inhalation of fine and ultrafine particles has been associated with adverse respiratory effects. Recent proposals to substantially reduce workplace exposure limits (WELs), including a respirable limit of 0.3 mg/m³ for ultrafine/nanoscale particles and 2.4 mg/m³ for fine/pigment-grade particles, have raised questions regarding future industry compliance with the proposed limits. This study analyzed de-identified exposure data sourced from the Western Australia Department of Local Government, Industry Regulation and Safety (LGIRS) Safety Regulatory System (SRS) to evaluate TiO2 exposures in the Western Australian (WA) mining industry. A total of 604 personal inhalable exposure samples collected between 2018 and 2025 were included. Descriptive statistics, exceedance analysis, and temporal trends were assessed against the current WEL of 10 mg/m³ for inhalable TiO2 and the proposed WELs of 0.3 mg/m³ for ultrafine/nanoscale TiO2 and 2.4 mg/m³ for fine/pigmentary-grade TiO2. Exposure levels were consistently low, with most results well below both the current and proposed WELs. Only one sample exceeded the numerical value of the proposed ultrafine/nanoscale limit, while the second-highest value, 0.12 mg/m³, remained below all proposed exposure limits. No samples exceeded the proposed 2.4 mg/m³ respirable WEL, and trends were stable or decreasing over time. Because the samples represented the inhalable fraction, comparison with proposed respirable limits provides conservative evidence of compliance. These findings indicate that the WA mining industry is well positioned to meet more stringent particle-size-specific exposure standards.