Personal differences in the breathing patterns and volumes and dust intakes of working miners. Final report on CEC Contract 7246-12/8/002

A study was carried out on the breathing patterns (breathing volume, breaths per minute and volume per breath) and the dust uptake of 62 miners at three collieries during their routine work at the coalface.Preliminary development and evaluation of equipment and checking of laboratory procedures were essential in view of the practical problems in carrying out the investigation under working conditions. The men wore a half-face mask fitted with a filter, respirometer and breath counter (this latter developed under CEC Contract 6253-22/08/016). The composite equipment was tested, underground. Inspiratory resistance of 40 mm had no noticeable effect on breathing pattern, and repeat measurements were acceptably precise. A special pre-filter was developed which allowed only the respirable dust to be deposited on the main filter. This afforded a method of assessing the uptake of respirable dust, a measurement not previously available. It is anticipated that this pre-filter will have wider general applications. It was possible to control successfully for the effect of changes in the moisture content of the respirator filters. Two laboratory methods for estimating the dust content of the respirator filters were used. Neither proved entirely successful, and so the estimates of dust weights were imprecise. Work on the development of more suitable respirator filters was indicated.In spite of the reluctance of some miners to wear the equipment in the restricted conditions at the coalface, so limiting the number of men studied and the range of characteristics they represented, the main objectives of the research were achieved. It was shown that breathing patterns of individual miners at their place of work do differ, and that these differences occur both in the general level of their breathing characteristics and in repeatability of these measurements. Differences between men were unambiguous when all those studied at a colliery were considered, and were also demonstrated clearly among men doing the same job. There was an association between breathing pattern and occupation within a colliery and this was described. Differences were also shown between men doing the same jobs in different collieries, and these may be related to seam thickness. There was some evidence from these data that breathing characteristics were related to age and physique, but conflicting patterns of association were found. In general an association between breathing pattern and dust uptake was not found, possibly because of imprecision in the dust measurements.Recommendations for further work are included.