New evidence concerning smoking and health.

In the last 20 years, and especially as a result of smoking and health studies, we have learned a great deal about the impact of all airborne substances on human health. We are now painfully aware of the many sources of toxic and carcinogenic agents in our air. New evidence shows a complex relationship existing for exposure from many sources of pollutants from the community, smoking and other personal habits. This new evidence indicates that these pollutants, especially those encountered in blue collar occupations, account for a far larger proportion of cancers of the lung and of other sites (and of other diseases) than has been heretofore thought to be the case.