74 The Canadian Journal of Diagnosis / July 2001 Is Your Patient’s Workplace Causing

Occupational lung diseases not only have a significant health impact on the affected individual, but they often result in workplace changes and significant socio-economic impact. The range and relative frequency ofoccupational lung diseases has changed significantly in Canada over the past 30 years. Occupational lung diseases that were relatively common before, such as silicosis and coal miners ’ pneumoco-niosis, are now uncommon conditions in Canada. Although silicosis can still be caused by sandblasting and occasionally by other types of exposures, it has become uncommon in Canadian underground min-ers. This is due to much improved dust-control measures, such as spraying water to keep dust down while drilling and blasting underground. Conversely, the diagnosis of occupational asthma caused by workplace sensitizers has risen, and this is now the most common chronic occupational lung disease in Canada.1,2 It is estimated that occupational asthma (usually due to an immunologic response to a work agent) accounts for about 7 % of all adult-onset asthma,3 and occupational factors may play a role in up to 30 % of adult asthma.4 There has been increased recognition of the role of workplace irri-tants in aggravating asthma and even, at times, causing asthma due to very hig