The secondary aims are: - to examine possible changes in systemic inflammatory markers and - to examine changes in lung function among Silicon Carbide processing workers during a period of 3 years. Possible changes in lung function will be monitored by spirometry and gas diffusion measurements (study A). Airway inflammatory responses and changes in circulating inflammatory markers will be assessed by examination of the induced sputum samples and blood samples every 6th month in a subgroup of workers (study B).