Climate and the prevalence of symptoms of asthma, allergic rhinitis, and atopic eczema in children
- 1Department of Epidemiology, University of Ulm, Ulm, Germany
- 2Department of Medical Informatics, Biometrics und Epidemiology, University of Bochum, Germany
- 3St George’s Hospital Medical School, London, UK
- 4Massey University, Wellington, New Zealand
- Correspondence to: Prof. Dr. med. S Weiland Department of Epidemiology, University of Ulm, Helmholzstr. 22, 89081 Ulm, Germany;
- Accepted 28 November 2003
Aims: To investigate the association between climate and atopic diseases using worldwide data from 146 centres of the International Study of Asthma and Allergies in Childhood (ISAAC).
Methods: Between 1992 and 1996, each centre studied random samples of children aged 13–14 and 6–7 years (approx. 3000 per age group and centre) using standardised written and video questionnaires on symptoms of asthma, allergic rhinoconjunctivitis, and atopic eczema during the past 12 months. Data on long term climatic conditions in the centres were abstracted from one standardised source, and mixed linear regression models calculated to take the clustering of centres within countries into account.
Results: In Western Europe (57 centres in 12 countries), the prevalence of asthma symptoms, assessed by written questionnaire, increased by 2.7% (95% CI 1.0% to 4.5%) with an increase in the estimated annual mean of indoor relative humidity of 10%. Similar associations were seen for the video questionnaire and the younger age group. Altitude and the annual variation of temperature and relative humidity outdoors were negatively associated with asthma symptoms. The prevalence of eczema symptoms correlated with latitude (positively) and mean annual outdoor temperature (negatively).
Conclusions: Results suggest that climate may affect the prevalence of asthma and atopic eczema in children.
The study was funded in part by the Innovative Medizinische Forschung (IMF) programme (WE-1-1-II/96-3) of the University of Münster, Germany