Globally there are around 10 million workers who routinely weld and are exposed to a metal fume aerosol of small particles of largely metal oxides and gases. Their medium- and long-term cardiorespiratory risks are incompletely understood.

This thesis describes a programme of novel research carried out in a large Middle Eastern shipyard. Four studies were completed. First, a systematic review of published cross-sectional surveys (N: 38) in welders were identified; a meta-analyses of 34 publications showed a clear excess of asthma (OR 1.65; 95% CI 1.14, 2.37) and chronic bronchitis (OR 1.92; 1.50, 2.45) that could not be explained by smoking. In contrast, there was remarkably, little summary evidence of deficits in lung function in welders.

Second, a cross-sectional survey of shipyard workers (N: 529, response rate 93%) showed no evidence of any decrements in lung or cardiac function in welders but suggested that symptoms of respiratory infections in winter were more common in this group (OR 2.65; 1.22, 5.78) than in matched referent workers. Support for this novel finding came from the third study, of clinical records held by the yard’s medical centre over an eleven-year period (N: 15,954). Consultations for respiratory infections were 72% higher in welders compared to office workers; there was a clear exposure-response relationship across workers with different intensities of welding. The fourth study, of a panel of 50 shipyard workers (response rate 100%) suggested a small cross-shift decline in lung function and increase in arterial stiffness.

These findings suggest, for the first time, that welders are susceptible to a wide range of respiratory infections. High quality, collaborative research in this setting is feasible; future studies could usefully examine in more detail – including microbiological - the relationship between welding fume exposure and respiratory infections. The potential health-benefits to the global community of welders are substantial.