In the year 1990 the European Community Respiratory Health Survey I (ECRHS I) demonstrated that the prevalence of these diseases was lowest in Iceland (www.ecrhs.org). In order to compare the prevalence of respiratory symptoms in Reykjavik over time, a new identical cross-sectional study was performed seventeen years later.
Both cohorts, were in the age group 20-44 years and randomly selected from the population in Reykjavik and suburbs. Both answered questionnaires about respiratory symptoms, nasal allergy and use of anti-asthmatic drugs. The second cohort was part of the EuroPrevall study (www.europrevall.org) performed in 2007.
Response rate was lower in 2007 (999 or 43.2%) than in 1990 (2.903 or 80.6%).The prevalence of attacks of asthma increased over time from 2.2% to 6.7% (p