A study of the exposure of British mineworkers to nitrous fumes and the effects on their health. Final report on CEC Contract 7253~/8/086

This report describes work which continues the previous CEC-supported study of nitrous fume in coal mines in relation to effects on health (CEC Contract No. 6253-44/8/019).Shift-average exposures to nitric oxide and nitrogen dioxide have been found to be well within the recommended safety limits in nine British collieries. Differences in the exposures of miners in different collieries and between different locations and occupations within collieries were observed, with diesel locomotive drivers having consistently higher’ shift-average exposures than other workers. Peak measurements of nitrogen dioxide indicated that levels very seldom exceeded the recommended short-term exposure limit and then only for short periods. On a few occasions nitric oxide levels in certain collieries were found to exceed its short-term exposure limit although always for less than five minutes and, on most occasions, by less than 30 per cent. As well as having highest shift-average exposures, diesel locomotive drivers were also found to be exposed to relatively high and frequent peak nitric oxide and nitrogen dioxide concentrations.Possible health effects of oxides of nitrogen were investigated by comparing the respiratory health of men with low past exposure against men with higher past exposure to these gases. No differences in forced expired volumes in one second or in the prevalences of cough, phlegm and breathlessness were found between the two population groups.Nitric oxide and nitrogen dioxide were found to adsorb on to respirable coal mine, coal and other mineral dusts in a stable manner and in measurable quantities. The adsorption of nitric oxide had no effect on the cytotoxicity of respirable dusts. Adsorption of nitrogen dioxide tended to reduce the cytotoxicities of the various minerals tested.