Investigations in dust surveillance and control in drivages, scourings and bord and pillar workings. Final report on CEC Contract 7253-21/8;/088088.

Investigations into dust surveillance procedures and control in drivages, scourings and “”bord and pillar workings were carried out by the environmental field staff of the Institute of Occupational Medicine. The object of the research was to provide data for the planning or updating of dust surveillance schemes, rather than the proposal of a particular system.An initial study was made of the various mechanisation and ventilation techniques employed throughout the UK coalfields, to find a representative selection of study sites, but the investigations were conducted mainly at collieries associated with the Pneumoconiosis Field Research (PFR) scheme.””Fixed Point”” gravimetric samplers were located at the statutory control sampling point and other locations around the drivages. Measurements at these points were made for the time at working place only to assess the effectiveness of the control sampling point and to provide data on the local variability of dust conditions. Personal samplers were worn for the whole time underground, including travelling, to provide data on individual daily exposure. Ventilation and operational details were also observed to assess their contribution to the dust conditions encountered. The usefulness of continuous monitoring instruments was also considered.Fixed point sampling showed consistent differences in control point concentrations associated with particular machine types and generally lower concentrations in exhaust ventilated drivages. The position of the ventilation duct orifice was found to have a direct bearing on dust conditions within the drivage, regardless of ventilation type. There were distinct differences in the local variation of dust conditions between forced and exhaust systems. It was also found that correct orientation of the gravimetric samplers could not be ensured, without the use of ventilation smoke tubes, due to the generally low level of ventilation velocities encountered. Underestimation of dust levels within the forward zones of drivages, by a sampler located at the present control point,indicates a need for special consideration to be given when these zones are occupied during the normal cycle of operations.Control point dust concentrations in continuous bord and pillar operations were higher than those in cyclic operations or in development drivages. Also of note in bord and pillar operations were the concentrations recorded during the shotfiring and loading phases of the cyclic operation.1 There was evidence to suggest that a stationary gravimetric sampler would be equally representative of the workforce exposure pattern as one associated with the undercutting operation. Bord and pillar data were sparse and further evaluation is desirable.Personal sampler measurements showed the drivage workforce to be exposed to highly variable conditions. Estimation of group shift exposures by means of fixed point gravimetric samplers was shown to be unreliable with a large spread. Individual exposure patterns show the rationale behind the present control sampling point to be correct in assuming that the machine operator is more liable to be the most heavily exposed. The number-of high personal concentrations recorded in zones where low dust concentrations are indicated by static instruments substantiated the view that in headings, the creation of localised dust clouds contributes greatly to individual exposure patterns. “”