Fig. 1From: Early life swimming pool exposure and asthma onset in children – a case-control studyFlow-chart of the second OLIN pediatric cohort. Cases were children with physician-diagnosed asthma at either the original survey at age 7–8 years or at the follow-ups at 11–12 and 14–15 years. Controls consisted of children without asthma, allergic rhinitis and asthma symptoms in any of the surveysBack to article page