An occupational health and industrial hygiene survey was carried out in Widia tool grinding industries in the area covered by Local Health Unit No. 60--Vimercate (Northern Italy). The principal objectives of the study were to assess occupational cobalt exposure, identify the measures required to improve the 'risk' situations, and implement specific health protocols. The results identified a variable level of occupational hazard in the tool grinding sector. An important factor in the containment of occupational exposure was, along with correct practical procedures, the existence of adequate primary prevention measures (aspiration systems over the machines). In the plants where good industrial hygiene conditions prevailed, environmental cobalt concentrations were below the TLV, whereas the levels recorded in plants with inadequate equipment were as much as 10 times the TLV. Similarly, urinary cobalt for the workers in these same plants was as much as 13 times higher than the reference population value. However, this was recorded in plants with good industrial hygiene conditions. After technical improvements, the results of biological monitoring showed an overall reduction in exposure indicator values.