Comparison of respirable dust concentrations between gravimetric weighing and real-time dust monitoring equipment in non-mining industries.

BACKGROUND

Gravimetric weighing remains the gold standard for mass concentration assessments; however, real-time (RT) instruments offer advantages such as immediate feedback and temporal resolution. This study evaluated the comparability of Nanozen DustCount 9000 RT measurements with its gravimetric weighing in non-mining industrial environments.

METHOD: Task-based stationary sampling was conducted at 11 sites in the Gauteng Province, South Africa, producing 20 paired gravimetric and RT measurements. RT outputs were analyzed as raw (RT) and density-adjusted (adjusted-RT) values. Comparability was assessed using Wilcoxon signed-rank tests, Bland-Altman analysis, and regression of proportional bias.

RESULTS

No significant differences were observed between gravimetric and RT (P = 0.067) or gravimetric and adjusted-RT (P = 0.277). Bias increased with higher concentrations, but measurements below 1 mg/m3 showed no significant proportional bias (gravimetric versus RT: R2 = 0.06, P = 0.34; gravimetric versus adjusted-RT: R2 = 0.02, P = 0.59).

CONCLUSION

The RT measurements demonstrated close correspondence with gravimetric results obtained from the Nanozen DustCount 9000 built-in filter cassette, particularly at concentrations below 1 mg/m3, suggesting this threshold as a cutoff point for reliable agreement.