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(1973). Brit. J. industr. Med., 30,[25][26][27][28][29][30][31][32][33][34][35][36]. A study of the acute and chronic changes in ventilatory capacity ofworkers in Lancashire cotton mills. A prospective study of workers in 14 cotton and two man-made fibre spinning mills in Lancashire was carried out over a three-year period. A questionnaire on respiratory symptoms was completed at the start of the survey and again two years later. Up to six measurements of ventilatory capacity were made at six-monthly intervals. From these measurements the rate at which the forced expiratory volume (FEV1) was declining (annual decline in FEV) was evaluated for 595 subjects. Six of the mills were visited on Mondays and in 199 operatives the ventilatory capacity was measured at both the beginning and end of the shift to evaluate its acute fall during work (Monday fall in FEV).The mean annual decline in FEV for cotton workers was 54 ml/year and it was only 32 ml/year for workers in the man-made fibre mills but this lower value was attributable almost entirely to one of the two mills. For the jobs near the carding engines the annual decline was 22 ml/year higher than for speed-frame tenters. The annual decline for cigarette smokers was 19 ml/year greater than for non-and ex-smokers. The annual decline in FEV was not found to be related to symptoms of byssinosis or bronchitis, nor to present dust levels, bioactivity of the dust or air pollution, although the expected effect attributable to byssinosis turned out to be less than that which the survey was designed to detect.The mean Monday fall in FEV was higher in cotton mills than in man-made fibre mills among those without symptoms of byssinosis and was correlated with present dust levels. For those with symptoms of byssinosis an increased Monday fall was found only in those processing coarse cotton.For those subjects who completed the respiratory questionnaire on two occasions the chronic and acute changes in FEV were examined in relation to the change in symptoms of byssinosis. No association was found for annual decline in FEV but the Monday fall in FEV was greater for those who developed byssinosis during the survey than for those who remained free of symptoms, and was less for those who lost their symptoms than for those who retained them.Previous investigations on the ventilatory capacity of Schilling (1956) reported a difference of 1 litre in the cotton workers have generally shown that those forced expiratory volume over i second (FEVO.75) workers with symptoms of byssinosis have lower between normal cotton workers and those with values of ventilatory capacity than those without. grade 2 byssinosis but later studies have shown smaller differences, e.g., Lammers, Schilling, and *Present address:

Objectives-To study the relation between occupational exposure to ceramic fibres during manufacture and respiratory health. Methods-The respiratory health of 628 current employees in the manufacture of ceramic fibres in seven European plants in three countries was studied with a respiratory questionnaire, lung function tests, and chest radiography. Simultaneous plant hygiene surveys measured subjects' current exposure to airborne ceramic fibres from personal samples with optical microscopy fibre counts. The measured exposures were combined with occupational histories to derive estimates of each subject's cumulative exposure to respirable fibres. Symptoms were related to current and cumulative exposure to ceramic fibres and lung function and findings from chest radiographs were related to cumulative exposure. Results-The mean duration of employment was 10-2 years and mean (range) cumulative exposure was 3-84 (0-22.94) (f.ml-'.y). Eye and skin symptoms were frequent in all plants and increased significantly, as did breathlessness and wheeze, with increasing current exposure. Dry cough and stuffy nose were less common in the least exposed group but did not increase with increasing exposure. After adjustment for the effects of age, sex, height, smoking, and past occupational exposures to respiratory hazards, there was a significant decrease in both forced expiratory volume in one second (FEV,) and forced midexpiratory flow related to cumulative exposure in current smokers (P < 0.05) and in FEV, in ex-smokers (P < 0.05). Small opacities were found in 13% of the chest radiographs; their prevalence was not related to cumulative exposure to ceramic fibres. Conclusions-It is concluded that exposure to ceramic fibres is associated with irritant symptoms similar to those seen in other exposures to man made mineral fibres (MMMFs) and that cumulative exposure to respirable ceramic fibres may cause airways obstruction by promoting the effects of cigarette smoke.

A study population of 3086 employees was identified in 18 carbon black production plants in seven

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