Background: At most, just 10% of adults and 35% of children in any given region of the world suffer from asthma. A phenomenon known as the "cohort effect" may be to blame for the fact that asthma is more prevalent in children than in adults. Research conducted recently that is based on populations shows that the increase in asthma prevalence that has been seen all across the world over the course of the last thirty years has begun to drop in industrialized nations. The number of people who take medication for asthma has expanded in tandem with this problem.