Field performance of the RespiCon for size-selective sampling of industrial wood processing dust.

The RespiCon sampler is a multistage virtual impactor that simultaneously collects the ISO/CEN/ACGIH size fractions of inhalable, thoracic, and respirable particulate matter. The field performance of the device for measurement of industrial wood processing dust was evaluated against reference size-selective samplers: the IOM sampler (inhalable dust), the GK 2.69 cyclone (thoracic dust), and the SKC aluminum cyclone (respirable dust). Seventy-one sets of area samples were collected from 10 wood processing plants, with the samplers mounted either in the free-field or on a two-dimensional bluff body. The geometric mean (range) dust levels across all plants measured by the reference samplers were: inhalable, 1.35 mg/ m3 (0.11-11.06); thoracic, 0.31 mg/m3 (0.05-1.38); and respirable, 0.10 mg/m3 (0.02-0.54). In comparing the RespiCon with the reference samplers, there was no significant difference between sampling in the free-field versus bluff-body modes. For inhalable dust, there was no significant difference between the RespiCon and the IOM sampler after applying a correction factor of 1.5 to the extrathoracic data obtained from the RespiCon. Without the correction factor, the RespiCon undersample inhalable dust by an average of 23%. For thoracic dust, the RespiCon was shown to oversample the extrathoracic dust fraction resulting in an overall error of 48%. A simple correction based on the inhalable and thoracic dust levels reported by the RespiCon is proposed. For respirable dust, there was a significant difference between the RespiCon and the SKC cyclone, but the data were equivocal due to imprecision in measurement of the low respirable dust concentrations encountered and the likelihood of bias in the reference sampler. Overall, the RespiCon sampler appears to be a suitable size-selective sampling device for industrial wood processing dust, although adjustments should be made to the inhalable and thoracic dust results.