Pulmonary effects of spot welding in automobile assembly.

Background: Spot welding is a type of resistance welding in which pieces of metals are pressed together and an electric current is passed through them. Spot welders are at risk of contact with some potentially hazardous agents but there are few studies about the respiratory effects of spot welding.

Aims: Our objective was to study lung function and respiratory symptoms among spot welders and office workers at an automobile assembly factory in Iran.

Methods: This was a cross-sectional study of 137 male spot welders and 129 office workers. We used a questionnaire to record demographic data, smoking habits, work history and respiratory symptoms. Spirometry was performed to assess lung function status. Metal fume samples from the respiratory zone of spot welders were analysed.

Results: The concentrations of metal fume were less than the American Conference of Industrial Hygienists (ACGIH) threshold limit values. There were significantly lower values for average forced expiratory volume in 1st second (FEV(1)), FEV(1)/forced vital capacity and 25-75% forced expiratory flow in spot welders compared to controls. There was also a significantly raised prevalence of respiratory symptoms (sputum and dyspnoea) in spot welders. Fifteen per cent of spot welders and 1% of controls had an obstructive pattern in spirometry.

Conclusions: Our survey suggests that spot welders are at risk of developing respiratory symptoms and decreasing pulmonary function values despite their exposure to components of welding fume being within ACGIH guidelines.