Most subjects with COPD have a mild disease. The underdiagnosis is related to disease-severity. Though being symptomatic, only a half of the subjects with severe COPD are properly labelled. Smoking and increasing age were the major risk factors and acted synergistic.

The patterns of tobacco use differed significantly between boys and girls. Though any tobacco use was more common among boys, girls were more likely to smoke, and boys were more likely to use snuff. Having asthma did not prevent the teenagers from smoking. Since having a smoking family member was the major risk factor for tobacco use, prevention programs should be directed at smoking families in addition to the individuals.