Background: Asthma is the most common chronic disease affecting youth worldwide. The prevalence of asthma has increased at least 3-fold during the past several decades. The reason for this increase remains unknown.
Objective: To examine one possible factor that may be affecting the increase in prevalence of asthma among youth.
Methods: Data on the incidence of asthma among youth were aggregated using the National Health Interview Survey (sample of 4,500 children) and were compared on an ecologic level with data on cigarette consumption in the United States from 1900 to 2003 from the American Lung Association.
Results: Our results suggest a parallel increase in the rates of cigarette use among adults and asthma in children. These findings show an increase in cigarette use during the past 4 birth cohorts, with subsequent leveling off at a population level with a progressively more prominent increase in cigarette use among women in the United States.
Conclusion: We present one possible factor that may be contributing to the epidemic of childhood asthma. We hypothesize that (1) there has been a marked increase in smoking during the past century, (2) this increase in smoking has resulted in a substantial increase in exposure to environmental tobacco smoke among children, and (3) increased exposure to environmental tobacco smoke has contributed to the increase in childhood asthma. Data on trends in cigarette use among adults and asthma prevalence among children during the past century are presented as ecological evidence in support of this hypothesis. Future studies will be needed to confirm these findings with community-level analyses in a variety of geographic regions.