Investigation of performance of personal samplers in industrial workplaces. Final report on HSE Contract 2191/R42.12

A life-size model of a human worker has been built to enable the performances of personal dust samplers in industrial orkplaces to be assessed in relation to inspirability. The aim was to provide a system whereby the actual dust levels experienced by the worker could be measured by both the simulated worker and by personal samplers mounted on his body. The work is a direct progression from recent studies on personal sampler performance that have been carried out in the ‘ideal’ conditions found in laboratory wind tunnels.The model, which is mounted on a trolley for moving around the workplace, is based on an anthropomorphic robotic arm, shrouded by a mannequin torso and with a head fixed to the robot ‘wrist’. The robotic arm provides limited movements to enable simulations to be made of the range of typical body movements displayed by workers in the course of their work. Simulated breathing through the mouth or nose is provided by a electronically-controlled breathing machine consisting of a pump, and a series of critical orifices and solenoid valves.As the development proceeded, a number of compromises were made in the design and operation of the model in relation to the fully-automated model first envisaged. Firstly, an operator is required to transport the model around the workplace, to operate the body movements and to ensure that the flowrate is maintained at the specified level. In addition it was not practicable to mimic the precise movements of individual workers. Nevertheless, with the model worker, a means has been provided, for the first time, of evaluating the performances of personal dust samplers in relation to dust exposure in industrial workplaces.Investigations were carried out in five different industrial workplaces chosen to represent a range of industrial processes, environmental conditions, and types of dust. At lease ten repeat samples were taken at each workplace to enable meaningful conclusions about sampler performances to be made, whilst covering as many industries as possible.Several broad conclusions were drawn from the statistical analysis of the data obtained. The IOM personal inspirable dust sampler performed satisfactorily in relation to inspirability, but this performance varied between the industries. The HSE seven-hole personal sampler signficantly underestimated inspirable dust exposure, but was not as affected by varying industrial conditions as the IOM personal sampler. In general both personal samplers collect more dust when exposed to fine particles than when exposed to the coarser ones. This effect was found to be more marked for the HSE sampler.Finally, the problems associated with using static samplers for estimating dust exposures were highlighted by the performance of the IOM static inspirable dust sampler which in general underestimated dust exposure, with performance varying from workplace to workplace.Whilst we have developed a means by which the performance of dust samplers, in relation to inspirability, can be evaluated in industrial workplaces, it was possible to carry out only limited field investigations. Further work is therefore required before decisions concerning sampler suitability can be made.